Hi Jens,
This is V3 of the Block IO controller patches on top of "for-2.6.33" branch
of block tree.
A consolidated patch can be found here:
http://people.redhat.com/vgoyal/io-controller/blkio-controller/blkio-controller-v3.patch
Changed from V2:
- Made group target latency calculations in proportion to group weight
instead of evenly dividing the slice among all the groups.
- Modified cfq_rb_first() to check "count" and return NULL if service tree
is empty.
- Did some reshuffling in patch order. Moved Documentation patch to the end.
Also moved group idling patch down the order.
- Fixed the "slice_end" issue raised by Gui during slice usage calculation.
Changes from V1:
- Rebased the patches for "for-2.6.33" branch.
- Currently dropped the support for priority class of groups. For the time
being only BE class groups are supported.
After the discussions at IO minisummit at Tokyo, Japan, it was agreed that
one single IO control policy at either leaf nodes or at higher level nodes
does not meet all the requirements and we need something so that we have
the capability to support more than one IO control policy (like proportional
weight division and max bandwidth control) and also have capability to
implement some of these policies at higher level logical devices.
It was agreed that CFQ is the right place to implement time based proportional
weight division policy. Other policies like max bandwidth control/throttling
will make more sense at higher level logical devices.
This patch introduces blkio cgroup controller. It provides the management
interface for the block IO control. The idea is that keep the interface
common and in the background we should be able to switch policies based on
user options. Hence user can control the IO throughout the IO stack with
a single cgroup interface.
Apart from blkio cgroup interface, this patchset also modifies CFQ to implement
time based proportional weight division of disk. CFQ already does it in flat
mode. It has been modified to do group IO scheduling also.
IO control is a huge problem and the moment we start addressing all the
issues in one patchset, it bloats to unmanageable proportions and then nothing
gets inside the kernel. So at io mini summit we agreed that lets take small
steps and once a piece of code is inside the kernel and stablized, take the
next step. So this is the first step.
Some parts of the code are based on BFQ patches posted by Paolo and Fabio.
Your feedback is welcome.
TODO
====
- Support async IO control (buffered writes).
Buffered writes is a beast and requires changes at many a places to solve the
problem and patchset becomes huge. Hence first we plan to support only sync
IO in control then work on async IO too.
Some of the work items identified are.
- Per memory cgroup dirty ratio
- Possibly modification of writeback to force writeback from a
particular cgroup.
- Implement IO tracking support so that a bio can be mapped to a cgroup.
- Per group request descriptor infrastructure in block layer.
- At CFQ level, implement per cfq_group async queues.
In this patchset, all the async IO goes in system wide queues and there are
no per group async queues. That means we will see service differentiation
only for sync IO only. Async IO willl be handled later.
- Support for higher level policies like max BW controller.
- Support groups of RT class also.
Thanks
Vivek
Documentation/cgroups/blkio-controller.txt | 100 +++
block/Kconfig | 22 +
block/Kconfig.iosched | 17 +
block/Makefile | 1 +
block/blk-cgroup.c | 312 ++++++++++
block/blk-cgroup.h | 90 +++
block/cfq-iosched.c | 922 ++++++++++++++++++++++++----
include/linux/cgroup_subsys.h | 6 +
include/linux/iocontext.h | 4 +
9 files changed, 1365 insertions(+), 109 deletions(-)
o This patch introduce the notion of cfq groups. Soon we will can have multiple
groups of different weights in the system.
o Various service trees (prioclass and workload type trees), will become per
cfq group. So hierarchy looks as follows.
cfq_groups
|
workload type
|
cfq queue
o When an scheduling decision has to be taken, first we select the cfq group
then workload with-in the group and then cfq queue with-in the workload
type.
o This patch just makes various workload service tree per cfq group and
introduce the function to be able to choose a group for scheduling.
Signed-off-by: Vivek Goyal <[email protected]>
---
block/cfq-iosched.c | 114 +++++++++++++++++++++++++++++++++++----------------
1 files changed, 79 insertions(+), 35 deletions(-)
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 1bcbd8c..aebb205 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -132,6 +132,7 @@ struct cfq_queue {
struct cfq_rb_root *service_tree;
struct cfq_queue *new_cfqq;
+ struct cfq_group *cfqg;
};
/*
@@ -153,6 +154,15 @@ enum wl_type_t {
SYNC_WORKLOAD = 2
};
+/* This is per cgroup per device grouping structure */
+struct cfq_group {
+ /*
+ * rr lists of queues with requests, onle rr for each priority class.
+ * Counts are embedded in the cfq_rb_root
+ */
+ struct cfq_rb_root service_trees[2][3];
+ struct cfq_rb_root service_tree_idle;
+};
/*
* Per block device queue structure
@@ -160,18 +170,15 @@ enum wl_type_t {
struct cfq_data {
struct request_queue *queue;
- /*
- * rr lists of queues with requests, onle rr for each priority class.
- * Counts are embedded in the cfq_rb_root
- */
- struct cfq_rb_root service_trees[2][3];
- struct cfq_rb_root service_tree_idle;
+ struct cfq_group root_group;
+
/*
* The priority currently being served
*/
enum wl_prio_t serving_prio;
enum wl_type_t serving_type;
unsigned long workload_expires;
+ struct cfq_group *serving_group;
/*
* Each priority tree is sorted by next_request position. These
@@ -233,14 +240,15 @@ struct cfq_data {
unsigned long last_end_sync_rq;
};
-static struct cfq_rb_root *service_tree_for(enum wl_prio_t prio,
+static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg,
+ enum wl_prio_t prio,
enum wl_type_t type,
struct cfq_data *cfqd)
{
if (prio == IDLE_WORKLOAD)
- return &cfqd->service_tree_idle;
+ return &cfqg->service_tree_idle;
- return &cfqd->service_trees[prio][type];
+ return &cfqg->service_trees[prio][type];
}
enum cfqq_state_flags {
@@ -308,12 +316,14 @@ static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
static inline int cfq_busy_queues_wl(enum wl_prio_t wl, struct cfq_data *cfqd)
{
+ struct cfq_group *cfqg = &cfqd->root_group;
+
if (wl == IDLE_WORKLOAD)
- return cfqd->service_tree_idle.count;
+ return cfqg->service_tree_idle.count;
- return cfqd->service_trees[wl][ASYNC_WORKLOAD].count
- + cfqd->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count
- + cfqd->service_trees[wl][SYNC_WORKLOAD].count;
+ return cfqg->service_trees[wl][ASYNC_WORKLOAD].count
+ + cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count
+ + cfqg->service_trees[wl][SYNC_WORKLOAD].count;
}
static void cfq_dispatch_insert(struct request_queue *, struct request *);
@@ -621,7 +631,8 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
struct cfq_rb_root *service_tree;
int left;
- service_tree = service_tree_for(cfqq_prio(cfqq), cfqq_type(cfqq), cfqd);
+ service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq),
+ cfqq_type(cfqq), cfqd);
if (cfq_class_idle(cfqq)) {
rb_key = CFQ_IDLE_DELAY;
parent = rb_last(&service_tree->rb);
@@ -1057,7 +1068,8 @@ static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
{
struct cfq_rb_root *service_tree =
- service_tree_for(cfqd->serving_prio, cfqd->serving_type, cfqd);
+ service_tree_for(cfqd->serving_group, cfqd->serving_prio,
+ cfqd->serving_type, cfqd);
if (RB_EMPTY_ROOT(&service_tree->rb))
return NULL;
@@ -1209,7 +1221,8 @@ static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
* in their service tree.
*/
if (!service_tree)
- service_tree = service_tree_for(prio, cfqq_type(cfqq), cfqd);
+ service_tree = service_tree_for(cfqq->cfqg, prio,
+ cfqq_type(cfqq), cfqd);
if (service_tree->count == 0)
return true;
@@ -1222,6 +1235,7 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd)
struct cfq_queue *cfqq = cfqd->active_queue;
struct cfq_io_context *cic;
unsigned long sl;
+ struct cfq_rb_root *st;
/*
* SSD device without seek penalty, disable idling. But only do so
@@ -1271,9 +1285,9 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd)
* fair distribution of slice time for a process doing back-to-back
* seeks.
*/
- if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD &&
- service_tree_for(cfqd->serving_prio, SYNC_NOIDLE_WORKLOAD, cfqd)
- ->count > 0) {
+ st = service_tree_for(cfqq->cfqg, cfqd->serving_prio,
+ SYNC_NOIDLE_WORKLOAD, cfqd);
+ if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD && st->count > 0) {
if (blk_queue_nonrot(cfqd->queue) || cfqd->hw_tag)
return;
sl = min(sl, msecs_to_jiffies(CFQ_MIN_TT));
@@ -1381,8 +1395,9 @@ static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
}
}
-static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd, enum wl_prio_t prio,
- bool prio_changed)
+static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd,
+ struct cfq_group *cfqg, enum wl_prio_t prio,
+ bool prio_changed)
{
struct cfq_queue *queue;
int i;
@@ -1396,10 +1411,10 @@ static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd, enum wl_prio_t prio,
* from SYNC_NOIDLE (first choice), or just SYNC
* over ASYNC
*/
- if (service_tree_for(prio, cur_best, cfqd)->count)
+ if (service_tree_for(cfqg, prio, cur_best, cfqd)->count)
return cur_best;
cur_best = SYNC_WORKLOAD;
- if (service_tree_for(prio, cur_best, cfqd)->count)
+ if (service_tree_for(cfqg, prio, cur_best, cfqd)->count)
return cur_best;
return ASYNC_WORKLOAD;
@@ -1407,7 +1422,7 @@ static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd, enum wl_prio_t prio,
for (i = 0; i < 3; ++i) {
/* otherwise, select the one with lowest rb_key */
- queue = cfq_rb_first(service_tree_for(prio, i, cfqd));
+ queue = cfq_rb_first(service_tree_for(cfqg, prio, i, cfqd));
if (queue &&
(!key_valid || time_before(queue->rb_key, lowest_key))) {
lowest_key = queue->rb_key;
@@ -1419,12 +1434,13 @@ static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd, enum wl_prio_t prio,
return cur_best;
}
-static void choose_service_tree(struct cfq_data *cfqd)
+static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
{
enum wl_prio_t previous_prio = cfqd->serving_prio;
bool prio_changed;
unsigned slice;
unsigned count;
+ struct cfq_rb_root *st;
/* Choose next priority. RT > BE > IDLE */
if (cfq_busy_queues_wl(RT_WORKLOAD, cfqd))
@@ -1443,8 +1459,9 @@ static void choose_service_tree(struct cfq_data *cfqd)
* expiration time
*/
prio_changed = (cfqd->serving_prio != previous_prio);
- count = service_tree_for(cfqd->serving_prio, cfqd->serving_type, cfqd)
- ->count;
+ st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type,
+ cfqd);
+ count = st->count;
/*
* If priority didn't change, check workload expiration,
@@ -1456,9 +1473,10 @@ static void choose_service_tree(struct cfq_data *cfqd)
/* otherwise select new workload type */
cfqd->serving_type =
- cfq_choose_wl(cfqd, cfqd->serving_prio, prio_changed);
- count = service_tree_for(cfqd->serving_prio, cfqd->serving_type, cfqd)
- ->count;
+ cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio, prio_changed);
+ st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type,
+ cfqd);
+ count = st->count;
/*
* the workload slice is computed as a fraction of target latency
@@ -1481,6 +1499,12 @@ static void choose_service_tree(struct cfq_data *cfqd)
cfqd->workload_expires = jiffies + slice;
}
+static void cfq_choose_cfqg(struct cfq_data *cfqd)
+{
+ cfqd->serving_group = &cfqd->root_group;
+ choose_service_tree(cfqd, &cfqd->root_group);
+}
+
/*
* Select a queue for service. If we have a current active queue,
* check whether to continue servicing it, or retrieve and set a new one.
@@ -1538,7 +1562,7 @@ new_queue:
* service tree
*/
if (!new_cfqq)
- choose_service_tree(cfqd);
+ cfq_choose_cfqg(cfqd);
cfqq = cfq_set_active_queue(cfqd, new_cfqq);
keep_queue:
@@ -1567,13 +1591,15 @@ static int cfq_forced_dispatch(struct cfq_data *cfqd)
struct cfq_queue *cfqq;
int dispatched = 0;
int i, j;
+ struct cfq_group *cfqg = &cfqd->root_group;
+
for (i = 0; i < 2; ++i)
for (j = 0; j < 3; ++j)
- while ((cfqq = cfq_rb_first(&cfqd->service_trees[i][j]))
+ while ((cfqq = cfq_rb_first(&cfqg->service_trees[i][j]))
!= NULL)
dispatched += __cfq_forced_dispatch_cfqq(cfqq);
- while ((cfqq = cfq_rb_first(&cfqd->service_tree_idle)) != NULL)
+ while ((cfqq = cfq_rb_first(&cfqg->service_tree_idle)) != NULL)
dispatched += __cfq_forced_dispatch_cfqq(cfqq);
cfq_slice_expired(cfqd, 0);
@@ -2044,14 +2070,26 @@ static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
cfqq->pid = pid;
}
+static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
+{
+ cfqq->cfqg = cfqg;
+}
+
+static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
+{
+ return &cfqd->root_group;
+}
+
static struct cfq_queue *
cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync,
struct io_context *ioc, gfp_t gfp_mask)
{
struct cfq_queue *cfqq, *new_cfqq = NULL;
struct cfq_io_context *cic;
+ struct cfq_group *cfqg;
retry:
+ cfqg = cfq_get_cfqg(cfqd, 1);
cic = cfq_cic_lookup(cfqd, ioc);
/* cic always exists here */
cfqq = cic_to_cfqq(cic, is_sync);
@@ -2082,6 +2120,7 @@ retry:
if (cfqq) {
cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
cfq_init_prio_data(cfqq, ioc);
+ cfq_link_cfqq_cfqg(cfqq, cfqg);
cfq_log_cfqq(cfqd, cfqq, "alloced");
} else
cfqq = &cfqd->oom_cfqq;
@@ -2914,15 +2953,19 @@ static void *cfq_init_queue(struct request_queue *q)
{
struct cfq_data *cfqd;
int i, j;
+ struct cfq_group *cfqg;
cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
if (!cfqd)
return NULL;
+ /* Init root group */
+ cfqg = &cfqd->root_group;
+
for (i = 0; i < 2; ++i)
for (j = 0; j < 3; ++j)
- cfqd->service_trees[i][j] = CFQ_RB_ROOT;
- cfqd->service_tree_idle = CFQ_RB_ROOT;
+ cfqg->service_trees[i][j] = CFQ_RB_ROOT;
+ cfqg->service_tree_idle = CFQ_RB_ROOT;
/*
* Not strictly needed (since RB_ROOT just clears the node and we
@@ -2939,6 +2982,7 @@ static void *cfq_init_queue(struct request_queue *q)
*/
cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
atomic_inc(&cfqd->oom_cfqq.ref);
+ cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group);
INIT_LIST_HEAD(&cfqd->cic_list);
--
1.6.2.5
o Currently cfqq deletes a queue from service tree if it is empty (even if
we might idle on the queue). This patch keeps the queue on service tree
hence associated group remains on the service tree until we decide that
we are not going to idle on the queue and expire it.
o This just helps in time accounting for queue/group and in implementation
of rest of the patches.
Signed-off-by: Vivek Goyal <[email protected]>
---
block/cfq-iosched.c | 72 +++++++++++++++++++++++++++++++++++++++-----------
1 files changed, 56 insertions(+), 16 deletions(-)
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index aebb205..d099880 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -374,7 +374,7 @@ static int cfq_queue_empty(struct request_queue *q)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
- return !cfqd->busy_queues;
+ return !cfqd->rq_queued;
}
/*
@@ -557,6 +557,10 @@ cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2,
*/
static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
{
+ /* Service tree is empty */
+ if (!root->count)
+ return NULL;
+
if (!root->left)
root->left = rb_first(&root->rb);
@@ -819,7 +823,6 @@ static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
static void cfq_del_rq_rb(struct request *rq)
{
struct cfq_queue *cfqq = RQ_CFQQ(rq);
- struct cfq_data *cfqd = cfqq->cfqd;
const int sync = rq_is_sync(rq);
BUG_ON(!cfqq->queued[sync]);
@@ -827,8 +830,17 @@ static void cfq_del_rq_rb(struct request *rq)
elv_rb_del(&cfqq->sort_list, rq);
- if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
- cfq_del_cfqq_rr(cfqd, cfqq);
+ if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
+ /*
+ * Queue will be deleted from service tree when we actually
+ * expire it later. Right now just remove it from prio tree
+ * as it is empty.
+ */
+ if (cfqq->p_root) {
+ rb_erase(&cfqq->p_node, cfqq->p_root);
+ cfqq->p_root = NULL;
+ }
+ }
}
static void cfq_add_rq_rb(struct request *rq)
@@ -1042,6 +1054,9 @@ __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
}
+ if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
+ cfq_del_cfqq_rr(cfqd, cfqq);
+
cfq_resort_rr_list(cfqd, cfqq);
if (cfqq == cfqd->active_queue)
@@ -1065,17 +1080,43 @@ static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
* Get next queue for service. Unless we have a queue preemption,
* we'll simply select the first cfqq in the service tree.
*/
-static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
+static struct cfq_queue *__cfq_get_next_queue(struct cfq_data *cfqd)
{
struct cfq_rb_root *service_tree =
service_tree_for(cfqd->serving_group, cfqd->serving_prio,
cfqd->serving_type, cfqd);
+ if (!cfqd->rq_queued)
+ return NULL;
+
if (RB_EMPTY_ROOT(&service_tree->rb))
return NULL;
return cfq_rb_first(service_tree);
}
+static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
+{
+ struct cfq_group *cfqg = &cfqd->root_group;
+ struct cfq_queue *cfqq;
+ int i, j;
+
+ if (!cfqd->rq_queued)
+ return NULL;
+
+ for (i = 0; i < 2; ++i) {
+ for (j = 0; j < 3; ++j) {
+ cfqq = cfq_rb_first(&cfqg->service_trees[i][j]);
+ if (cfqq)
+ return cfqq;
+ }
+ }
+
+ cfqq = cfq_rb_first(&cfqg->service_tree_idle);
+ if (cfqq)
+ return cfqq;
+ return NULL;
+}
+
/*
* Get and set a new active queue for service.
*/
@@ -1083,7 +1124,7 @@ static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
struct cfq_queue *cfqq)
{
if (!cfqq)
- cfqq = cfq_get_next_queue(cfqd);
+ cfqq = __cfq_get_next_queue(cfqd);
__cfq_set_active_queue(cfqd, cfqq);
return cfqq;
@@ -1517,6 +1558,8 @@ static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
if (!cfqq)
goto new_queue;
+ if (!cfqd->rq_queued)
+ return NULL;
/*
* The active queue has run out of time, expire it and select new.
*/
@@ -1579,6 +1622,10 @@ static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
}
BUG_ON(!list_empty(&cfqq->fifo));
+
+ /* By default cfqq is not expired if it is empty. Do it explicitly */
+ __cfq_slice_expired(cfqq->cfqd, cfqq, 0);
+
return dispatched;
}
@@ -1590,16 +1637,8 @@ static int cfq_forced_dispatch(struct cfq_data *cfqd)
{
struct cfq_queue *cfqq;
int dispatched = 0;
- int i, j;
- struct cfq_group *cfqg = &cfqd->root_group;
-
- for (i = 0; i < 2; ++i)
- for (j = 0; j < 3; ++j)
- while ((cfqq = cfq_rb_first(&cfqg->service_trees[i][j]))
- != NULL)
- dispatched += __cfq_forced_dispatch_cfqq(cfqq);
- while ((cfqq = cfq_rb_first(&cfqg->service_tree_idle)) != NULL)
+ while ((cfqq = cfq_get_next_queue(cfqd)) != NULL)
dispatched += __cfq_forced_dispatch_cfqq(cfqq);
cfq_slice_expired(cfqd, 0);
@@ -1770,13 +1809,14 @@ static void cfq_put_queue(struct cfq_queue *cfqq)
cfq_log_cfqq(cfqd, cfqq, "put_queue");
BUG_ON(rb_first(&cfqq->sort_list));
BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
- BUG_ON(cfq_cfqq_on_rr(cfqq));
if (unlikely(cfqd->active_queue == cfqq)) {
__cfq_slice_expired(cfqd, cfqq, 0);
cfq_schedule_dispatch(cfqd);
}
+ BUG_ON(cfq_cfqq_on_rr(cfqq));
+
kmem_cache_free(cfq_pool, cfqq);
}
--
1.6.2.5
o So far we just had one cfq_group in cfq_data. To create space for more than
one cfq_group, we need to have a service tree of groups where all the groups
can be queued if they have active cfq queues backlogged in these.
Signed-off-by: Vivek Goyal <[email protected]>
---
block/cfq-iosched.c | 137 +++++++++++++++++++++++++++++++++++++++++++++++++-
1 files changed, 134 insertions(+), 3 deletions(-)
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index d099880..73d93af 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -77,8 +77,9 @@ struct cfq_rb_root {
struct rb_root rb;
struct rb_node *left;
unsigned count;
+ u64 min_vdisktime;
};
-#define CFQ_RB_ROOT (struct cfq_rb_root) { RB_ROOT, NULL, 0, }
+#define CFQ_RB_ROOT (struct cfq_rb_root) { RB_ROOT, NULL, 0, 0, }
/*
* Per process-grouping structure
@@ -156,6 +157,16 @@ enum wl_type_t {
/* This is per cgroup per device grouping structure */
struct cfq_group {
+ /* group service_tree member */
+ struct rb_node rb_node;
+
+ /* group service_tree key */
+ u64 vdisktime;
+ bool on_st;
+
+ /* number of cfqq currently on this group */
+ int nr_cfqq;
+
/*
* rr lists of queues with requests, onle rr for each priority class.
* Counts are embedded in the cfq_rb_root
@@ -170,6 +181,8 @@ struct cfq_group {
struct cfq_data {
struct request_queue *queue;
+ /* Root service tree for cfq_groups */
+ struct cfq_rb_root grp_service_tree;
struct cfq_group root_group;
/*
@@ -245,6 +258,9 @@ static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg,
enum wl_type_t type,
struct cfq_data *cfqd)
{
+ if (!cfqg)
+ return NULL;
+
if (prio == IDLE_WORKLOAD)
return &cfqg->service_tree_idle;
@@ -570,6 +586,17 @@ static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
return NULL;
}
+static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
+{
+ if (!root->left)
+ root->left = rb_first(&root->rb);
+
+ if (root->left)
+ return rb_entry(root->left, struct cfq_group, rb_node);
+
+ return NULL;
+}
+
static void rb_erase_init(struct rb_node *n, struct rb_root *root)
{
rb_erase(n, root);
@@ -621,6 +648,83 @@ static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
}
+static inline s64
+cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
+{
+ return cfqg->vdisktime - st->min_vdisktime;
+}
+
+static void
+__cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
+{
+ struct rb_node **node = &st->rb.rb_node;
+ struct rb_node *parent = NULL;
+ struct cfq_group *__cfqg;
+ s64 key = cfqg_key(st, cfqg);
+ int left = 1;
+
+ while (*node != NULL) {
+ parent = *node;
+ __cfqg = rb_entry(parent, struct cfq_group, rb_node);
+
+ if (key < cfqg_key(st, __cfqg))
+ node = &parent->rb_left;
+ else {
+ node = &parent->rb_right;
+ left = 0;
+ }
+ }
+
+ if (left)
+ st->left = &cfqg->rb_node;
+
+ rb_link_node(&cfqg->rb_node, parent, node);
+ rb_insert_color(&cfqg->rb_node, &st->rb);
+}
+
+static void
+cfq_group_service_tree_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
+{
+ struct cfq_rb_root *st = &cfqd->grp_service_tree;
+ struct cfq_group *__cfqg;
+ struct rb_node *n;
+
+ cfqg->nr_cfqq++;
+ if (cfqg->on_st)
+ return;
+
+ /*
+ * Currently put the group at the end. Later implement something
+ * so that groups get lesser vtime based on their weights, so that
+ * if group does not loose all if it was not continously backlogged.
+ */
+ n = rb_last(&st->rb);
+ if (n) {
+ __cfqg = rb_entry(n, struct cfq_group, rb_node);
+ cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
+ } else
+ cfqg->vdisktime = st->min_vdisktime;
+
+ __cfq_group_service_tree_add(st, cfqg);
+ cfqg->on_st = true;
+}
+
+static void
+cfq_group_service_tree_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
+{
+ struct cfq_rb_root *st = &cfqd->grp_service_tree;
+
+ BUG_ON(cfqg->nr_cfqq < 1);
+ cfqg->nr_cfqq--;
+ /* If there are other cfq queues under this group, don't delete it */
+ if (cfqg->nr_cfqq)
+ return;
+
+ cfqg->on_st = false;
+ if (!RB_EMPTY_NODE(&cfqg->rb_node))
+ cfq_rb_erase(&cfqg->rb_node, st);
+}
+
/*
* The cfqd->service_trees holds all pending cfq_queue's that have
* requests waiting to be processed. It is sorted in the order that
@@ -703,6 +807,7 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
rb_link_node(&cfqq->rb_node, parent, p);
rb_insert_color(&cfqq->rb_node, &service_tree->rb);
service_tree->count++;
+ cfq_group_service_tree_add(cfqd, cfqq->cfqg);
}
static struct cfq_queue *
@@ -813,6 +918,8 @@ static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
cfqq->p_root = NULL;
}
+ cfq_group_service_tree_del(cfqd, cfqq->cfqg);
+
BUG_ON(!cfqd->busy_queues);
cfqd->busy_queues--;
}
@@ -1089,6 +1196,9 @@ static struct cfq_queue *__cfq_get_next_queue(struct cfq_data *cfqd)
if (!cfqd->rq_queued)
return NULL;
+ /* There is nothing to dispatch */
+ if (!service_tree)
+ return NULL;
if (RB_EMPTY_ROOT(&service_tree->rb))
return NULL;
return cfq_rb_first(service_tree);
@@ -1483,6 +1593,12 @@ static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
unsigned count;
struct cfq_rb_root *st;
+ if (!cfqg) {
+ cfqd->serving_prio = IDLE_WORKLOAD;
+ cfqd->workload_expires = jiffies + 1;
+ return;
+ }
+
/* Choose next priority. RT > BE > IDLE */
if (cfq_busy_queues_wl(RT_WORKLOAD, cfqd))
cfqd->serving_prio = RT_WORKLOAD;
@@ -1540,10 +1656,21 @@ static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
cfqd->workload_expires = jiffies + slice;
}
+static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
+{
+ struct cfq_rb_root *st = &cfqd->grp_service_tree;
+
+ if (RB_EMPTY_ROOT(&st->rb))
+ return NULL;
+ return cfq_rb_first_group(st);
+}
+
static void cfq_choose_cfqg(struct cfq_data *cfqd)
{
- cfqd->serving_group = &cfqd->root_group;
- choose_service_tree(cfqd, &cfqd->root_group);
+ struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
+
+ cfqd->serving_group = cfqg;
+ choose_service_tree(cfqd, cfqg);
}
/*
@@ -2999,6 +3126,9 @@ static void *cfq_init_queue(struct request_queue *q)
if (!cfqd)
return NULL;
+ /* Init root service tree */
+ cfqd->grp_service_tree = CFQ_RB_ROOT;
+
/* Init root group */
cfqg = &cfqd->root_group;
@@ -3006,6 +3136,7 @@ static void *cfq_init_queue(struct request_queue *q)
for (j = 0; j < 3; ++j)
cfqg->service_trees[i][j] = CFQ_RB_ROOT;
cfqg->service_tree_idle = CFQ_RB_ROOT;
+ RB_CLEAR_NODE(&cfqg->rb_node);
/*
* Not strictly needed (since RB_ROOT just clears the node and we
--
1.6.2.5
o So far we had 300ms soft target latency system wide. Now with the
introduction of cfq groups, divide that latency by number of groups so
that one can come up with group target latency which will be helpful
in determining the workload slice with-in group and also the dynamic
slice length of the cfq queue.
Signed-off-by: Vivek Goyal <[email protected]>
---
block/cfq-iosched.c | 65 +++++++++++++++++++++++++++++++++++---------------
1 files changed, 45 insertions(+), 20 deletions(-)
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 73d93af..11256c3 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -78,6 +78,7 @@ struct cfq_rb_root {
struct rb_node *left;
unsigned count;
u64 min_vdisktime;
+ unsigned total_weight;
};
#define CFQ_RB_ROOT (struct cfq_rb_root) { RB_ROOT, NULL, 0, 0, }
@@ -167,6 +168,8 @@ struct cfq_group {
/* number of cfqq currently on this group */
int nr_cfqq;
+ /* Per group busy queus average. Useful for workload slice calc. */
+ unsigned int busy_queues_avg[2];
/*
* rr lists of queues with requests, onle rr for each priority class.
* Counts are embedded in the cfq_rb_root
@@ -184,6 +187,8 @@ struct cfq_data {
/* Root service tree for cfq_groups */
struct cfq_rb_root grp_service_tree;
struct cfq_group root_group;
+ /* Number of active cfq groups on group service tree */
+ int nr_groups;
/*
* The priority currently being served
@@ -201,7 +206,6 @@ struct cfq_data {
struct rb_root prio_trees[CFQ_PRIO_LISTS];
unsigned int busy_queues;
- unsigned int busy_queues_avg[2];
int rq_in_driver[2];
int sync_flight;
@@ -330,10 +334,10 @@ static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
return SYNC_WORKLOAD;
}
-static inline int cfq_busy_queues_wl(enum wl_prio_t wl, struct cfq_data *cfqd)
+static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl,
+ struct cfq_data *cfqd,
+ struct cfq_group *cfqg)
{
- struct cfq_group *cfqg = &cfqd->root_group;
-
if (wl == IDLE_WORKLOAD)
return cfqg->service_tree_idle.count;
@@ -420,18 +424,27 @@ cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
* to quickly follows sudden increases and decrease slowly
*/
-static inline unsigned cfq_get_avg_queues(struct cfq_data *cfqd, bool rt)
+static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
+ struct cfq_group *cfqg, bool rt)
{
unsigned min_q, max_q;
unsigned mult = cfq_hist_divisor - 1;
unsigned round = cfq_hist_divisor / 2;
- unsigned busy = cfq_busy_queues_wl(rt, cfqd);
+ unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
- min_q = min(cfqd->busy_queues_avg[rt], busy);
- max_q = max(cfqd->busy_queues_avg[rt], busy);
- cfqd->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
+ min_q = min(cfqg->busy_queues_avg[rt], busy);
+ max_q = max(cfqg->busy_queues_avg[rt], busy);
+ cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
cfq_hist_divisor;
- return cfqd->busy_queues_avg[rt];
+ return cfqg->busy_queues_avg[rt];
+}
+
+static inline unsigned
+cfq_group_latency(struct cfq_data *cfqd, struct cfq_group *cfqg)
+{
+ struct cfq_rb_root *st = &cfqd->grp_service_tree;
+
+ return cfq_target_latency * cfqg->weight / st->total_weight;
}
static inline void
@@ -439,12 +452,17 @@ cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
{
unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
if (cfqd->cfq_latency) {
- /* interested queues (we consider only the ones with the same
- * priority class) */
- unsigned iq = cfq_get_avg_queues(cfqd, cfq_class_rt(cfqq));
+ /*
+ * interested queues (we consider only the ones with the same
+ * priority class in the cfq group)
+ */
+ unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
+ cfq_class_rt(cfqq));
unsigned sync_slice = cfqd->cfq_slice[1];
unsigned expect_latency = sync_slice * iq;
- if (expect_latency > cfq_target_latency) {
+ unsigned group_target_lat = cfq_group_latency(cfqd, cfqq->cfqg);
+
+ if (expect_latency > group_target_lat) {
unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
/* scale low_slice according to IO priority
* and sync vs async */
@@ -452,7 +470,7 @@ cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
min(slice, base_low_slice * slice / sync_slice);
/* the adapted slice value is scaled to fit all iqs
* into the target latency */
- slice = max(slice * cfq_target_latency / expect_latency,
+ slice = max(slice * group_target_lat / expect_latency,
low_slice);
}
}
@@ -707,6 +725,8 @@ cfq_group_service_tree_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
__cfq_group_service_tree_add(st, cfqg);
cfqg->on_st = true;
+ cfqd->nr_groups++;
+ st->total_weight += cfqg->weight;
}
static void
@@ -721,6 +741,8 @@ cfq_group_service_tree_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
return;
cfqg->on_st = false;
+ cfqd->nr_groups--;
+ st->total_weight -= cfqg->weight;
if (!RB_EMPTY_NODE(&cfqg->rb_node))
cfq_rb_erase(&cfqg->rb_node, st);
}
@@ -1592,6 +1614,7 @@ static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
unsigned slice;
unsigned count;
struct cfq_rb_root *st;
+ int group_target_latency;
if (!cfqg) {
cfqd->serving_prio = IDLE_WORKLOAD;
@@ -1600,9 +1623,9 @@ static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
}
/* Choose next priority. RT > BE > IDLE */
- if (cfq_busy_queues_wl(RT_WORKLOAD, cfqd))
+ if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
cfqd->serving_prio = RT_WORKLOAD;
- else if (cfq_busy_queues_wl(BE_WORKLOAD, cfqd))
+ else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
cfqd->serving_prio = BE_WORKLOAD;
else {
cfqd->serving_prio = IDLE_WORKLOAD;
@@ -1640,9 +1663,11 @@ static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
* proportional to the number of queues in that workload, over
* all the queues in the same priority class
*/
- slice = cfq_target_latency * count /
- max_t(unsigned, cfqd->busy_queues_avg[cfqd->serving_prio],
- cfq_busy_queues_wl(cfqd->serving_prio, cfqd));
+ group_target_latency = cfq_group_latency(cfqd, cfqg);
+
+ slice = group_target_latency * count /
+ max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio],
+ cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg));
if (cfqd->serving_type == ASYNC_WORKLOAD)
/* async workload slice is scaled down according to
--
1.6.2.5
o This is basic implementation of blkio controller cgroup interface. This is
the common interface visible to user space and should be used by different
IO control policies as we implement those.
Signed-off-by: Vivek Goyal <[email protected]>
---
block/Kconfig | 13 +++
block/Kconfig.iosched | 1 +
block/Makefile | 1 +
block/blk-cgroup.c | 177 +++++++++++++++++++++++++++++++++++++++++
block/blk-cgroup.h | 58 +++++++++++++
include/linux/cgroup_subsys.h | 6 ++
include/linux/iocontext.h | 4 +
7 files changed, 260 insertions(+), 0 deletions(-)
create mode 100644 block/blk-cgroup.c
create mode 100644 block/blk-cgroup.h
diff --git a/block/Kconfig b/block/Kconfig
index 9be0b56..6ba1a8e 100644
--- a/block/Kconfig
+++ b/block/Kconfig
@@ -77,6 +77,19 @@ config BLK_DEV_INTEGRITY
T10/SCSI Data Integrity Field or the T13/ATA External Path
Protection. If in doubt, say N.
+config BLK_CGROUP
+ bool
+ depends on CGROUPS
+ default n
+ ---help---
+ Generic block IO controller cgroup interface. This is the common
+ cgroup interface which should be used by various IO controlling
+ policies.
+
+ Currently, CFQ IO scheduler uses it to recognize task groups and
+ control disk bandwidth allocation (proportional time slice allocation)
+ to such task groups.
+
endif # BLOCK
config BLOCK_COMPAT
diff --git a/block/Kconfig.iosched b/block/Kconfig.iosched
index 8bd1051..be0280d 100644
--- a/block/Kconfig.iosched
+++ b/block/Kconfig.iosched
@@ -23,6 +23,7 @@ config IOSCHED_DEADLINE
config IOSCHED_CFQ
tristate "CFQ I/O scheduler"
+ select BLK_CGROUP
default y
---help---
The CFQ I/O scheduler tries to distribute bandwidth equally
diff --git a/block/Makefile b/block/Makefile
index 7914108..cb2d515 100644
--- a/block/Makefile
+++ b/block/Makefile
@@ -8,6 +8,7 @@ obj-$(CONFIG_BLOCK) := elevator.o blk-core.o blk-tag.o blk-sysfs.o \
blk-iopoll.o ioctl.o genhd.o scsi_ioctl.o
obj-$(CONFIG_BLK_DEV_BSG) += bsg.o
+obj-$(CONFIG_BLK_CGROUP) += blk-cgroup.o
obj-$(CONFIG_IOSCHED_NOOP) += noop-iosched.o
obj-$(CONFIG_IOSCHED_DEADLINE) += deadline-iosched.o
obj-$(CONFIG_IOSCHED_CFQ) += cfq-iosched.o
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
new file mode 100644
index 0000000..4f6afd7
--- /dev/null
+++ b/block/blk-cgroup.c
@@ -0,0 +1,177 @@
+/*
+ * Common Block IO controller cgroup interface
+ *
+ * Based on ideas and code from CFQ, CFS and BFQ:
+ * Copyright (C) 2003 Jens Axboe <[email protected]>
+ *
+ * Copyright (C) 2008 Fabio Checconi <[email protected]>
+ * Paolo Valente <[email protected]>
+ *
+ * Copyright (C) 2009 Vivek Goyal <[email protected]>
+ * Nauman Rafique <[email protected]>
+ */
+#include <linux/ioprio.h>
+#include "blk-cgroup.h"
+
+struct blkio_cgroup blkio_root_cgroup = { .weight = 2*BLKIO_WEIGHT_DEFAULT };
+
+struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup)
+{
+ return container_of(cgroup_subsys_state(cgroup, blkio_subsys_id),
+ struct blkio_cgroup, css);
+}
+
+void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
+ struct blkio_group *blkg, void *key)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&blkcg->lock, flags);
+ rcu_assign_pointer(blkg->key, key);
+ hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list);
+ spin_unlock_irqrestore(&blkcg->lock, flags);
+}
+
+int blkiocg_del_blkio_group(struct blkio_group *blkg)
+{
+ /* Implemented later */
+ return 0;
+}
+
+/* called under rcu_read_lock(). */
+struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg, void *key)
+{
+ struct blkio_group *blkg;
+ struct hlist_node *n;
+ void *__key;
+
+ hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) {
+ __key = blkg->key;
+ if (__key == key)
+ return blkg;
+ }
+
+ return NULL;
+}
+
+#define SHOW_FUNCTION(__VAR) \
+static u64 blkiocg_##__VAR##_read(struct cgroup *cgroup, \
+ struct cftype *cftype) \
+{ \
+ struct blkio_cgroup *blkcg; \
+ \
+ blkcg = cgroup_to_blkio_cgroup(cgroup); \
+ return (u64)blkcg->__VAR; \
+}
+
+SHOW_FUNCTION(weight);
+#undef SHOW_FUNCTION
+
+static int
+blkiocg_weight_write(struct cgroup *cgroup, struct cftype *cftype, u64 val)
+{
+ struct blkio_cgroup *blkcg;
+
+ if (val < BLKIO_WEIGHT_MIN || val > BLKIO_WEIGHT_MAX)
+ return -EINVAL;
+
+ blkcg = cgroup_to_blkio_cgroup(cgroup);
+ blkcg->weight = (unsigned int)val;
+ return 0;
+}
+
+struct cftype blkio_files[] = {
+ {
+ .name = "weight",
+ .read_u64 = blkiocg_weight_read,
+ .write_u64 = blkiocg_weight_write,
+ },
+};
+
+static int blkiocg_populate(struct cgroup_subsys *subsys, struct cgroup *cgroup)
+{
+ return cgroup_add_files(cgroup, subsys, blkio_files,
+ ARRAY_SIZE(blkio_files));
+}
+
+static void blkiocg_destroy(struct cgroup_subsys *subsys, struct cgroup *cgroup)
+{
+ struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
+
+ free_css_id(&blkio_subsys, &blkcg->css);
+ kfree(blkcg);
+}
+
+static struct cgroup_subsys_state *
+blkiocg_create(struct cgroup_subsys *subsys, struct cgroup *cgroup)
+{
+ struct blkio_cgroup *blkcg, *parent_blkcg;
+
+ if (!cgroup->parent) {
+ blkcg = &blkio_root_cgroup;
+ goto done;
+ }
+
+ /* Currently we do not support hierarchy deeper than two level (0,1) */
+ parent_blkcg = cgroup_to_blkio_cgroup(cgroup->parent);
+ if (css_depth(&parent_blkcg->css) > 0)
+ return ERR_PTR(-EINVAL);
+
+ blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL);
+ if (!blkcg)
+ return ERR_PTR(-ENOMEM);
+
+ blkcg->weight = BLKIO_WEIGHT_DEFAULT;
+done:
+ spin_lock_init(&blkcg->lock);
+ INIT_HLIST_HEAD(&blkcg->blkg_list);
+
+ return &blkcg->css;
+}
+
+/*
+ * We cannot support shared io contexts, as we have no mean to support
+ * two tasks with the same ioc in two different groups without major rework
+ * of the main cic data structures. For now we allow a task to change
+ * its cgroup only if it's the only owner of its ioc.
+ */
+static int blkiocg_can_attach(struct cgroup_subsys *subsys,
+ struct cgroup *cgroup, struct task_struct *tsk,
+ bool threadgroup)
+{
+ struct io_context *ioc;
+ int ret = 0;
+
+ /* task_lock() is needed to avoid races with exit_io_context() */
+ task_lock(tsk);
+ ioc = tsk->io_context;
+ if (ioc && atomic_read(&ioc->nr_tasks) > 1)
+ ret = -EINVAL;
+ task_unlock(tsk);
+
+ return ret;
+}
+
+static void blkiocg_attach(struct cgroup_subsys *subsys, struct cgroup *cgroup,
+ struct cgroup *prev, struct task_struct *tsk,
+ bool threadgroup)
+{
+ struct io_context *ioc;
+
+ task_lock(tsk);
+ ioc = tsk->io_context;
+ if (ioc)
+ ioc->cgroup_changed = 1;
+ task_unlock(tsk);
+}
+
+struct cgroup_subsys blkio_subsys = {
+ .name = "blkio",
+ .create = blkiocg_create,
+ .can_attach = blkiocg_can_attach,
+ .attach = blkiocg_attach,
+ .destroy = blkiocg_destroy,
+ .populate = blkiocg_populate,
+ .subsys_id = blkio_subsys_id,
+ .use_id = 1,
+};
diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
new file mode 100644
index 0000000..ba5703f
--- /dev/null
+++ b/block/blk-cgroup.h
@@ -0,0 +1,58 @@
+#ifndef _BLK_CGROUP_H
+#define _BLK_CGROUP_H
+/*
+ * Common Block IO controller cgroup interface
+ *
+ * Based on ideas and code from CFQ, CFS and BFQ:
+ * Copyright (C) 2003 Jens Axboe <[email protected]>
+ *
+ * Copyright (C) 2008 Fabio Checconi <[email protected]>
+ * Paolo Valente <[email protected]>
+ *
+ * Copyright (C) 2009 Vivek Goyal <[email protected]>
+ * Nauman Rafique <[email protected]>
+ */
+
+#include <linux/cgroup.h>
+
+struct blkio_cgroup {
+ struct cgroup_subsys_state css;
+ unsigned int weight;
+ spinlock_t lock;
+ struct hlist_head blkg_list;
+};
+
+struct blkio_group {
+ /* An rcu protected unique identifier for the group */
+ void *key;
+ struct hlist_node blkcg_node;
+};
+
+#define BLKIO_WEIGHT_MIN 100
+#define BLKIO_WEIGHT_MAX 1000
+#define BLKIO_WEIGHT_DEFAULT 500
+
+#ifdef CONFIG_BLK_CGROUP
+extern struct blkio_cgroup blkio_root_cgroup;
+extern struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup);
+extern void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
+ struct blkio_group *blkg, void *key);
+extern int blkiocg_del_blkio_group(struct blkio_group *blkg);
+extern struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg,
+ void *key);
+#else
+static inline struct blkio_cgroup *
+cgroup_to_blkio_cgroup(struct cgroup *cgroup) { return NULL; }
+
+static inline void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
+ struct blkio_group *blkg, void *key)
+{
+}
+
+static inline int
+blkiocg_del_blkio_group(struct blkio_group *blkg) { return 0; }
+
+static inline struct blkio_group *
+blkiocg_lookup_group(struct blkio_cgroup *blkcg, void *key) { return NULL; }
+#endif
+#endif /* _BLK_CGROUP_H */
diff --git a/include/linux/cgroup_subsys.h b/include/linux/cgroup_subsys.h
index 9c8d31b..ccefff0 100644
--- a/include/linux/cgroup_subsys.h
+++ b/include/linux/cgroup_subsys.h
@@ -60,3 +60,9 @@ SUBSYS(net_cls)
#endif
/* */
+
+#ifdef CONFIG_BLK_CGROUP
+SUBSYS(blkio)
+#endif
+
+/* */
diff --git a/include/linux/iocontext.h b/include/linux/iocontext.h
index eb73632..d61b0b8 100644
--- a/include/linux/iocontext.h
+++ b/include/linux/iocontext.h
@@ -68,6 +68,10 @@ struct io_context {
unsigned short ioprio;
unsigned short ioprio_changed;
+#ifdef CONFIG_BLK_CGROUP
+ unsigned short cgroup_changed;
+#endif
+
/*
* For request batching
*/
--
1.6.2.5
o Bring in the per cfq group weight and how vdisktime is calculated for the
group. Also bring in the functionality of updating the min_vdisktime of
the group service tree.
Signed-off-by: Vivek Goyal <[email protected]>
---
block/Kconfig.iosched | 9 ++++++-
block/cfq-iosched.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++-
2 files changed, 69 insertions(+), 2 deletions(-)
diff --git a/block/Kconfig.iosched b/block/Kconfig.iosched
index be0280d..fa95fa7 100644
--- a/block/Kconfig.iosched
+++ b/block/Kconfig.iosched
@@ -23,7 +23,6 @@ config IOSCHED_DEADLINE
config IOSCHED_CFQ
tristate "CFQ I/O scheduler"
- select BLK_CGROUP
default y
---help---
The CFQ I/O scheduler tries to distribute bandwidth equally
@@ -33,6 +32,14 @@ config IOSCHED_CFQ
This is the default I/O scheduler.
+config CFQ_GROUP_IOSCHED
+ bool "CFQ Group Scheduling support"
+ depends on IOSCHED_CFQ && CGROUPS
+ select BLK_CGROUP
+ default n
+ ---help---
+ Enable group IO scheduling in CFQ.
+
choice
prompt "Default I/O scheduler"
default DEFAULT_CFQ
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 11256c3..0754d61 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -13,6 +13,7 @@
#include <linux/rbtree.h>
#include <linux/ioprio.h>
#include <linux/blktrace_api.h>
+#include "blk-cgroup.h"
/*
* tunables
@@ -49,6 +50,7 @@ static const int cfq_hist_divisor = 4;
#define CFQ_SLICE_SCALE (5)
#define CFQ_HW_QUEUE_MIN (5)
+#define CFQ_SERVICE_SHIFT 12
#define RQ_CIC(rq) \
((struct cfq_io_context *) (rq)->elevator_private)
@@ -79,6 +81,7 @@ struct cfq_rb_root {
unsigned count;
u64 min_vdisktime;
unsigned total_weight;
+ struct rb_node *active;
};
#define CFQ_RB_ROOT (struct cfq_rb_root) { RB_ROOT, NULL, 0, 0, }
@@ -163,6 +166,7 @@ struct cfq_group {
/* group service_tree key */
u64 vdisktime;
+ unsigned int weight;
bool on_st;
/* number of cfqq currently on this group */
@@ -418,6 +422,51 @@ cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
}
+static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg)
+{
+ u64 d = delta << CFQ_SERVICE_SHIFT;
+
+ d = d * BLKIO_WEIGHT_DEFAULT;
+ do_div(d, cfqg->weight);
+ return d;
+}
+
+static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
+{
+ s64 delta = (s64)(vdisktime - min_vdisktime);
+ if (delta > 0)
+ min_vdisktime = vdisktime;
+
+ return min_vdisktime;
+}
+
+static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
+{
+ s64 delta = (s64)(vdisktime - min_vdisktime);
+ if (delta < 0)
+ min_vdisktime = vdisktime;
+
+ return min_vdisktime;
+}
+
+static void update_min_vdisktime(struct cfq_rb_root *st)
+{
+ u64 vdisktime = st->min_vdisktime;
+ struct cfq_group *cfqg;
+
+ if (st->active) {
+ cfqg = rb_entry(st->active, struct cfq_group, rb_node);
+ vdisktime = cfqg->vdisktime;
+ }
+
+ if (st->left) {
+ cfqg = rb_entry(st->left, struct cfq_group, rb_node);
+ vdisktime = min_vdisktime(vdisktime, cfqg->vdisktime);
+ }
+
+ st->min_vdisktime = max_vdisktime(st->min_vdisktime, vdisktime);
+}
+
/*
* get averaged number of queues of RT/BE priority.
* average is updated, with a formula that gives more weight to higher numbers,
@@ -734,8 +783,12 @@ cfq_group_service_tree_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
{
struct cfq_rb_root *st = &cfqd->grp_service_tree;
+ if (st->active == &cfqg->rb_node)
+ st->active = NULL;
+
BUG_ON(cfqg->nr_cfqq < 1);
cfqg->nr_cfqq--;
+
/* If there are other cfq queues under this group, don't delete it */
if (cfqg->nr_cfqq)
return;
@@ -1684,10 +1737,14 @@ static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
{
struct cfq_rb_root *st = &cfqd->grp_service_tree;
+ struct cfq_group *cfqg;
if (RB_EMPTY_ROOT(&st->rb))
return NULL;
- return cfq_rb_first_group(st);
+ cfqg = cfq_rb_first_group(st);
+ st->active = &cfqg->rb_node;
+ update_min_vdisktime(st);
+ return cfqg;
}
static void cfq_choose_cfqg(struct cfq_data *cfqd)
@@ -3163,6 +3220,9 @@ static void *cfq_init_queue(struct request_queue *q)
cfqg->service_tree_idle = CFQ_RB_ROOT;
RB_CLEAR_NODE(&cfqg->rb_node);
+ /* Give preference to root group over other groups */
+ cfqg->weight = 2*BLKIO_WEIGHT_DEFAULT;
+
/*
* Not strictly needed (since RB_ROOT just clears the node and we
* zeroed cfqd on alloc), but better be safe in case someone decides
--
1.6.2.5
o This patch introduces the functionality to do the accounting of group time
when a queue expires. This time used decides which is the group to go
next.
o Also introduce the functionlity to save and restore the workload type
context with-in group. It might happen that once we expire the cfq queue
and group, a different group will schedule in and we will lose the context
of the workload type. Hence save and restore it upon queue expiry.
Signed-off-by: Vivek Goyal <[email protected]>
---
block/cfq-iosched.c | 76 +++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 76 insertions(+), 0 deletions(-)
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 0754d61..4c05d45 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -114,6 +114,10 @@ struct cfq_queue {
/* fifo list of requests in sort_list */
struct list_head fifo;
+ /* time when queue got scheduled in to dispatch first request. */
+ unsigned long dispatch_start;
+ /* time when first request from queue completed and slice started. */
+ unsigned long slice_start;
unsigned long slice_end;
long slice_resid;
unsigned int slice_dispatch;
@@ -180,6 +184,10 @@ struct cfq_group {
*/
struct cfq_rb_root service_trees[2][3];
struct cfq_rb_root service_tree_idle;
+
+ unsigned long saved_workload_slice;
+ enum wl_type_t saved_workload;
+ enum wl_prio_t saved_serving_prio;
};
/*
@@ -523,6 +531,7 @@ cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
low_slice);
}
}
+ cfqq->slice_start = jiffies;
cfqq->slice_end = jiffies + slice;
cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
}
@@ -798,6 +807,55 @@ cfq_group_service_tree_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
st->total_weight -= cfqg->weight;
if (!RB_EMPTY_NODE(&cfqg->rb_node))
cfq_rb_erase(&cfqg->rb_node, st);
+ cfqg->saved_workload_slice = 0;
+}
+
+static inline unsigned long cfq_cfqq_slice_usage(struct cfq_queue *cfqq)
+{
+ unsigned long slice_used, allocated_slice;
+
+ /*
+ * Queue got expired before even a single request completed or
+ * got expired immediately after first request completion.
+ */
+ if (!cfqq->slice_start || cfqq->slice_start == jiffies) {
+ /*
+ * Also charge the seek time incurred to the group, otherwise
+ * if there are mutiple queues in the group, each can dispatch
+ * a single request on seeky media and cause lots of seek time
+ * and group will never know it.
+ */
+ slice_used = max_t(unsigned long,
+ (jiffies - cfqq->dispatch_start), 1);
+ } else {
+ slice_used = jiffies - cfqq->slice_start;
+ allocated_slice = cfqq->slice_end - cfqq->slice_start;
+ if (slice_used > allocated_slice)
+ slice_used = allocated_slice;
+ }
+
+ cfq_log_cfqq(cfqq->cfqd, cfqq, "sl_used=%lu", slice_used);
+ return slice_used;
+}
+
+static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
+ unsigned long service)
+{
+ struct cfq_rb_root *st = &cfqd->grp_service_tree;
+
+ /* Can't update vdisktime while group is on service tree */
+ cfq_rb_erase(&cfqg->rb_node, st);
+ cfqg->vdisktime += cfq_scale_slice(service, cfqg);
+ __cfq_group_service_tree_add(st, cfqg);
+
+ /* This group is being expired. Save the context */
+ if (time_after(cfqd->workload_expires, jiffies)) {
+ cfqg->saved_workload_slice = cfqd->workload_expires
+ - jiffies;
+ cfqg->saved_workload = cfqd->serving_type;
+ cfqg->saved_serving_prio = cfqd->serving_prio;
+ } else
+ cfqg->saved_workload_slice = 0;
}
/*
@@ -813,6 +871,7 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
unsigned long rb_key;
struct cfq_rb_root *service_tree;
int left;
+ int new_cfqq = 1;
service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq),
cfqq_type(cfqq), cfqd);
@@ -841,6 +900,7 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
}
if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
+ new_cfqq = 0;
/*
* same position, nothing more to do
*/
@@ -882,6 +942,8 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
rb_link_node(&cfqq->rb_node, parent, p);
rb_insert_color(&cfqq->rb_node, &service_tree->rb);
service_tree->count++;
+ if (add_front || !new_cfqq)
+ return;
cfq_group_service_tree_add(cfqd, cfqq->cfqg);
}
@@ -1199,6 +1261,8 @@ static void __cfq_set_active_queue(struct cfq_data *cfqd,
{
if (cfqq) {
cfq_log_cfqq(cfqd, cfqq, "set_active");
+ cfqq->slice_start = 0;
+ cfqq->dispatch_start = jiffies;
cfqq->slice_end = 0;
cfqq->slice_dispatch = 0;
@@ -1236,6 +1300,8 @@ __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
}
+ cfq_group_served(cfqd, cfqq->cfqg, cfq_cfqq_slice_usage(cfqq));
+
if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
cfq_del_cfqq_rr(cfqd, cfqq);
@@ -1244,6 +1310,9 @@ __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
if (cfqq == cfqd->active_queue)
cfqd->active_queue = NULL;
+ if (&cfqq->cfqg->rb_node == cfqd->grp_service_tree.active)
+ cfqd->grp_service_tree.active = NULL;
+
if (cfqd->active_cic) {
put_io_context(cfqd->active_cic->ioc);
cfqd->active_cic = NULL;
@@ -1752,6 +1821,13 @@ static void cfq_choose_cfqg(struct cfq_data *cfqd)
struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
cfqd->serving_group = cfqg;
+
+ /* Restore the workload type data */
+ if (cfqg->saved_workload_slice) {
+ cfqd->workload_expires = jiffies + cfqg->saved_workload_slice;
+ cfqd->serving_type = cfqg->saved_workload;
+ cfqd->serving_prio = cfqg->saved_serving_prio;
+ }
choose_service_tree(cfqd, cfqg);
}
--
1.6.2.5
o Determine the cgroup IO submitting task belongs to and create the cfq
group if it does not exist already.
o Also link cfqq and associated cfq group.
o Currently all async IO is mapped to root group.
Signed-off-by: Vivek Goyal <[email protected]>
---
block/cfq-iosched.c | 113 ++++++++++++++++++++++++++++++++++++++++++++++-----
1 files changed, 102 insertions(+), 11 deletions(-)
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 4c05d45..9653caf 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -188,6 +188,10 @@ struct cfq_group {
unsigned long saved_workload_slice;
enum wl_type_t saved_workload;
enum wl_prio_t saved_serving_prio;
+ struct blkio_group blkg;
+#ifdef CONFIG_CFQ_GROUP_IOSCHED
+ struct hlist_node cfqd_node;
+#endif
};
/*
@@ -267,8 +271,13 @@ struct cfq_data {
struct cfq_queue oom_cfqq;
unsigned long last_end_sync_rq;
+
+ /* List of cfq groups being managed on this device*/
+ struct hlist_head cfqg_list;
};
+static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
+
static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg,
enum wl_prio_t prio,
enum wl_type_t type,
@@ -858,6 +867,91 @@ static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
cfqg->saved_workload_slice = 0;
}
+#ifdef CONFIG_CFQ_GROUP_IOSCHED
+static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg)
+{
+ if (blkg)
+ return container_of(blkg, struct cfq_group, blkg);
+ return NULL;
+}
+
+static struct cfq_group *
+cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create)
+{
+ struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
+ struct cfq_group *cfqg = NULL;
+ void *key = cfqd;
+ int i, j;
+
+ /* Do we need to take this reference */
+ if (!css_tryget(&blkcg->css))
+ return NULL;;
+
+ cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key));
+ if (cfqg || !create)
+ goto done;
+
+ cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node);
+ if (!cfqg)
+ goto done;
+
+ cfqg->weight = blkcg->weight;
+
+ for (i = 0; i < 2; ++i)
+ for (j = 0; j < 3; ++j)
+ cfqg->service_trees[i][j] = CFQ_RB_ROOT;
+ cfqg->service_tree_idle = CFQ_RB_ROOT;
+ RB_CLEAR_NODE(&cfqg->rb_node);
+
+ /* Add group onto cgroup list */
+ blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd);
+
+ /* Add group on cfqd list */
+ hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
+
+done:
+ css_put(&blkcg->css);
+ return cfqg;
+}
+
+/*
+ * Search for the cfq group current task belongs to. If create = 1, then also
+ * create the cfq group if it does not exist. request_queue lock must be held.
+ */
+static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
+{
+ struct cgroup *cgroup;
+ struct cfq_group *cfqg = NULL;
+
+ rcu_read_lock();
+ cgroup = task_cgroup(current, blkio_subsys_id);
+ cfqg = cfq_find_alloc_cfqg(cfqd, cgroup, create);
+ if (!cfqg && create)
+ cfqg = &cfqd->root_group;
+ rcu_read_unlock();
+ return cfqg;
+}
+
+static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
+{
+ /* Currently, all async queues are mapped to root group */
+ if (!cfq_cfqq_sync(cfqq))
+ cfqg = &cfqq->cfqd->root_group;
+
+ cfqq->cfqg = cfqg;
+}
+#else /* GROUP_IOSCHED */
+static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
+{
+ return &cfqd->root_group;
+}
+static inline void
+cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
+ cfqq->cfqg = cfqg;
+}
+
+#endif /* GROUP_IOSCHED */
+
/*
* The cfqd->service_trees holds all pending cfq_queue's that have
* requests waiting to be processed. It is sorted in the order that
@@ -1350,13 +1444,17 @@ static struct cfq_queue *__cfq_get_next_queue(struct cfq_data *cfqd)
static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
{
- struct cfq_group *cfqg = &cfqd->root_group;
+ struct cfq_group *cfqg;
struct cfq_queue *cfqq;
int i, j;
if (!cfqd->rq_queued)
return NULL;
+ cfqg = cfq_get_next_cfqg(cfqd);
+ if (!cfqg)
+ return NULL;
+
for (i = 0; i < 2; ++i) {
for (j = 0; j < 3; ++j) {
cfqq = cfq_rb_first(&cfqg->service_trees[i][j]);
@@ -2395,16 +2493,6 @@ static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
cfqq->pid = pid;
}
-static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
-{
- cfqq->cfqg = cfqg;
-}
-
-static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
-{
- return &cfqd->root_group;
-}
-
static struct cfq_queue *
cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync,
struct io_context *ioc, gfp_t gfp_mask)
@@ -3299,6 +3387,9 @@ static void *cfq_init_queue(struct request_queue *q)
/* Give preference to root group over other groups */
cfqg->weight = 2*BLKIO_WEIGHT_DEFAULT;
+#ifdef CONFIG_CFQ_GROUP_IOSCHED
+ blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg, (void *)cfqd);
+#endif
/*
* Not strictly needed (since RB_ROOT just clears the node and we
* zeroed cfqd on alloc), but better be safe in case someone decides
--
1.6.2.5
o One can choose to change elevator or delete a cgroup. Implement group
reference counting so that both elevator exit and cgroup deletion can
take place gracefully.
Signed-off-by: Vivek Goyal <[email protected]>
Signed-off-by: Nauman Rafique <[email protected]>
---
block/blk-cgroup.c | 66 +++++++++++++++++++++++++++++++-
block/blk-cgroup.h | 1 +
block/cfq-iosched.c | 104 +++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 169 insertions(+), 2 deletions(-)
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 4f6afd7..0426ab6 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -13,6 +13,8 @@
#include <linux/ioprio.h>
#include "blk-cgroup.h"
+extern void cfq_unlink_blkio_group(void *, struct blkio_group *);
+
struct blkio_cgroup blkio_root_cgroup = { .weight = 2*BLKIO_WEIGHT_DEFAULT };
struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup)
@@ -28,14 +30,43 @@ void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
spin_lock_irqsave(&blkcg->lock, flags);
rcu_assign_pointer(blkg->key, key);
+ blkg->blkcg_id = css_id(&blkcg->css);
hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list);
spin_unlock_irqrestore(&blkcg->lock, flags);
}
+static void __blkiocg_del_blkio_group(struct blkio_group *blkg)
+{
+ hlist_del_init_rcu(&blkg->blkcg_node);
+ blkg->blkcg_id = 0;
+}
+
+/*
+ * returns 0 if blkio_group was still on cgroup list. Otherwise returns 1
+ * indicating that blk_group was unhashed by the time we got to it.
+ */
int blkiocg_del_blkio_group(struct blkio_group *blkg)
{
- /* Implemented later */
- return 0;
+ struct blkio_cgroup *blkcg;
+ unsigned long flags;
+ struct cgroup_subsys_state *css;
+ int ret = 1;
+
+ rcu_read_lock();
+ css = css_lookup(&blkio_subsys, blkg->blkcg_id);
+ if (!css)
+ goto out;
+
+ blkcg = container_of(css, struct blkio_cgroup, css);
+ spin_lock_irqsave(&blkcg->lock, flags);
+ if (!hlist_unhashed(&blkg->blkcg_node)) {
+ __blkiocg_del_blkio_group(blkg);
+ ret = 0;
+ }
+ spin_unlock_irqrestore(&blkcg->lock, flags);
+out:
+ rcu_read_unlock();
+ return ret;
}
/* called under rcu_read_lock(). */
@@ -97,8 +128,39 @@ static int blkiocg_populate(struct cgroup_subsys *subsys, struct cgroup *cgroup)
static void blkiocg_destroy(struct cgroup_subsys *subsys, struct cgroup *cgroup)
{
struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
+ unsigned long flags;
+ struct blkio_group *blkg;
+ void *key;
+ rcu_read_lock();
+remove_entry:
+ spin_lock_irqsave(&blkcg->lock, flags);
+
+ if (hlist_empty(&blkcg->blkg_list)) {
+ spin_unlock_irqrestore(&blkcg->lock, flags);
+ goto done;
+ }
+
+ blkg = hlist_entry(blkcg->blkg_list.first, struct blkio_group,
+ blkcg_node);
+ key = rcu_dereference(blkg->key);
+ __blkiocg_del_blkio_group(blkg);
+
+ spin_unlock_irqrestore(&blkcg->lock, flags);
+
+ /*
+ * This blkio_group is being unlinked as associated cgroup is going
+ * away. Let all the IO controlling policies know about this event.
+ *
+ * Currently this is static call to one io controlling policy. Once
+ * we have more policies in place, we need some dynamic registration
+ * of callback function.
+ */
+ cfq_unlink_blkio_group(key, blkg);
+ goto remove_entry;
+done:
free_css_id(&blkio_subsys, &blkcg->css);
+ rcu_read_unlock();
kfree(blkcg);
}
diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index ba5703f..cd50a2f 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -26,6 +26,7 @@ struct blkio_group {
/* An rcu protected unique identifier for the group */
void *key;
struct hlist_node blkcg_node;
+ unsigned short blkcg_id;
};
#define BLKIO_WEIGHT_MIN 100
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 9653caf..046f876 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -191,6 +191,7 @@ struct cfq_group {
struct blkio_group blkg;
#ifdef CONFIG_CFQ_GROUP_IOSCHED
struct hlist_node cfqd_node;
+ atomic_t ref;
#endif
};
@@ -903,6 +904,14 @@ cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create)
cfqg->service_tree_idle = CFQ_RB_ROOT;
RB_CLEAR_NODE(&cfqg->rb_node);
+ /*
+ * Take the initial reference that will be released on destroy
+ * This can be thought of a joint reference by cgroup and
+ * elevator which will be dropped by either elevator exit
+ * or cgroup deletion path depending on who is exiting first.
+ */
+ atomic_set(&cfqg->ref, 1);
+
/* Add group onto cgroup list */
blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd);
@@ -939,7 +948,86 @@ static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
cfqg = &cfqq->cfqd->root_group;
cfqq->cfqg = cfqg;
+ /* cfqq reference on cfqg */
+ atomic_inc(&cfqq->cfqg->ref);
+}
+
+static void cfq_put_cfqg(struct cfq_group *cfqg)
+{
+ struct cfq_rb_root *st;
+ int i, j;
+
+ BUG_ON(atomic_read(&cfqg->ref) <= 0);
+ if (!atomic_dec_and_test(&cfqg->ref))
+ return;
+
+ for (i = 0; i < 2; ++i)
+ for (j = 0; j < 3; ++j) {
+ st = &cfqg->service_trees[i][j];
+ BUG_ON(!RB_EMPTY_ROOT(&st->rb));
+ BUG_ON(st->active != NULL);
+ }
+
+ BUG_ON(!RB_EMPTY_ROOT(&cfqg->service_tree_idle.rb));
+ BUG_ON(cfqg->service_tree_idle.active != NULL);
+
+ kfree(cfqg);
+}
+
+static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg)
+{
+ /* Something wrong if we are trying to remove same group twice */
+ BUG_ON(hlist_unhashed(&cfqg->cfqd_node));
+
+ hlist_del_init(&cfqg->cfqd_node);
+
+ /*
+ * Put the reference taken at the time of creation so that when all
+ * queues are gone, group can be destroyed.
+ */
+ cfq_put_cfqg(cfqg);
}
+
+static void cfq_release_cfq_groups(struct cfq_data *cfqd)
+{
+ struct hlist_node *pos, *n;
+ struct cfq_group *cfqg;
+
+ hlist_for_each_entry_safe(cfqg, pos, n, &cfqd->cfqg_list, cfqd_node) {
+ /*
+ * If cgroup removal path got to blk_group first and removed
+ * it from cgroup list, then it will take care of destroying
+ * cfqg also.
+ */
+ if (!blkiocg_del_blkio_group(&cfqg->blkg))
+ cfq_destroy_cfqg(cfqd, cfqg);
+ }
+}
+
+/*
+ * Blk cgroup controller notification saying that blkio_group object is being
+ * delinked as associated cgroup object is going away. That also means that
+ * no new IO will come in this group. So get rid of this group as soon as
+ * any pending IO in the group is finished.
+ *
+ * This function is called under rcu_read_lock(). key is the rcu protected
+ * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu
+ * read lock.
+ *
+ * "key" was fetched from blkio_group under blkio_cgroup->lock. That means
+ * it should not be NULL as even if elevator was exiting, cgroup deltion
+ * path got to it first.
+ */
+void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg)
+{
+ unsigned long flags;
+ struct cfq_data *cfqd = key;
+
+ spin_lock_irqsave(cfqd->queue->queue_lock, flags);
+ cfq_destroy_cfqg(cfqd, cfqg_of_blkg(blkg));
+ spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
+}
+
#else /* GROUP_IOSCHED */
static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
{
@@ -950,6 +1038,9 @@ cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
cfqq->cfqg = cfqg;
}
+static void cfq_release_cfq_groups(struct cfq_data *cfqd) {}
+static inline void cfq_put_cfqg(struct cfq_group *cfqg) {}
+
#endif /* GROUP_IOSCHED */
/*
@@ -2178,11 +2269,13 @@ static int cfq_dispatch_requests(struct request_queue *q, int force)
* task holds one reference to the queue, dropped when task exits. each rq
* in-flight on this queue also holds a reference, dropped when rq is freed.
*
+ * Each cfq queue took a reference on the parent group. Drop it now.
* queue lock must be held here.
*/
static void cfq_put_queue(struct cfq_queue *cfqq)
{
struct cfq_data *cfqd = cfqq->cfqd;
+ struct cfq_group *cfqg;
BUG_ON(atomic_read(&cfqq->ref) <= 0);
@@ -2192,6 +2285,7 @@ static void cfq_put_queue(struct cfq_queue *cfqq)
cfq_log_cfqq(cfqd, cfqq, "put_queue");
BUG_ON(rb_first(&cfqq->sort_list));
BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
+ cfqg = cfqq->cfqg;
if (unlikely(cfqd->active_queue == cfqq)) {
__cfq_slice_expired(cfqd, cfqq, 0);
@@ -2201,6 +2295,7 @@ static void cfq_put_queue(struct cfq_queue *cfqq)
BUG_ON(cfq_cfqq_on_rr(cfqq));
kmem_cache_free(cfq_pool, cfqq);
+ cfq_put_cfqg(cfqg);
}
/*
@@ -3354,11 +3449,15 @@ static void cfq_exit_queue(struct elevator_queue *e)
}
cfq_put_async_queues(cfqd);
+ cfq_release_cfq_groups(cfqd);
+ blkiocg_del_blkio_group(&cfqd->root_group.blkg);
spin_unlock_irq(q->queue_lock);
cfq_shutdown_timer_wq(cfqd);
+ /* Wait for cfqg->blkg->key accessors to exit their grace periods. */
+ synchronize_rcu();
kfree(cfqd);
}
@@ -3388,6 +3487,11 @@ static void *cfq_init_queue(struct request_queue *q)
cfqg->weight = 2*BLKIO_WEIGHT_DEFAULT;
#ifdef CONFIG_CFQ_GROUP_IOSCHED
+ /*
+ * Take a reference to root group which we never drop. This is just
+ * to make sure that cfq_put_cfqg() does not try to kfree root group
+ */
+ atomic_set(&cfqg->ref, 1);
blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg, (void *)cfqd);
#endif
/*
--
1.6.2.5
o Some debugging aids for CFQ.
Signed-off-by: Vivek Goyal <[email protected]>
---
block/Kconfig | 9 +++++++++
block/Kconfig.iosched | 9 +++++++++
block/blk-cgroup.c | 4 ++++
block/blk-cgroup.h | 13 +++++++++++++
block/cfq-iosched.c | 17 +++++++++++++++++
5 files changed, 52 insertions(+), 0 deletions(-)
diff --git a/block/Kconfig b/block/Kconfig
index 6ba1a8e..e20fbde 100644
--- a/block/Kconfig
+++ b/block/Kconfig
@@ -90,6 +90,15 @@ config BLK_CGROUP
control disk bandwidth allocation (proportional time slice allocation)
to such task groups.
+config DEBUG_BLK_CGROUP
+ bool
+ depends on BLK_CGROUP
+ default n
+ ---help---
+ Enable some debugging help. Currently it stores the cgroup path
+ in the blk group which can be used by cfq for tracing various
+ group related activity.
+
endif # BLOCK
config BLOCK_COMPAT
diff --git a/block/Kconfig.iosched b/block/Kconfig.iosched
index fa95fa7..b71abfb 100644
--- a/block/Kconfig.iosched
+++ b/block/Kconfig.iosched
@@ -40,6 +40,15 @@ config CFQ_GROUP_IOSCHED
---help---
Enable group IO scheduling in CFQ.
+config DEBUG_CFQ_IOSCHED
+ bool "Debug CFQ Scheduling"
+ depends on CFQ_GROUP_IOSCHED
+ select DEBUG_BLK_CGROUP
+ default n
+ ---help---
+ Enable CFQ IO scheduling debugging in CFQ. Currently it makes
+ blktrace output more verbose.
+
choice
prompt "Default I/O scheduler"
default DEFAULT_CFQ
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 0426ab6..6bc99a3 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -33,6 +33,10 @@ void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
blkg->blkcg_id = css_id(&blkcg->css);
hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list);
spin_unlock_irqrestore(&blkcg->lock, flags);
+#ifdef CONFIG_DEBUG_BLK_CGROUP
+ /* Need to take css reference ? */
+ cgroup_path(blkcg->css.cgroup, blkg->path, sizeof(blkg->path));
+#endif
}
static void __blkiocg_del_blkio_group(struct blkio_group *blkg)
diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index cd50a2f..3573199 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -27,12 +27,25 @@ struct blkio_group {
void *key;
struct hlist_node blkcg_node;
unsigned short blkcg_id;
+#ifdef CONFIG_DEBUG_BLK_CGROUP
+ /* Store cgroup path */
+ char path[128];
+#endif
};
#define BLKIO_WEIGHT_MIN 100
#define BLKIO_WEIGHT_MAX 1000
#define BLKIO_WEIGHT_DEFAULT 500
+#ifdef CONFIG_DEBUG_BLK_CGROUP
+static inline char *blkg_path(struct blkio_group *blkg)
+{
+ return blkg->path;
+}
+#else
+static inline char *blkg_path(struct blkio_group *blkg) { return NULL; }
+#endif
+
#ifdef CONFIG_BLK_CGROUP
extern struct blkio_cgroup blkio_root_cgroup;
extern struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup);
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 046f876..005a8ee 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -332,8 +332,21 @@ CFQ_CFQQ_FNS(sync);
CFQ_CFQQ_FNS(coop);
#undef CFQ_CFQQ_FNS
+#ifdef CONFIG_DEBUG_CFQ_IOSCHED
+#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
+ blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
+ cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
+ blkg_path(&(cfqq)->cfqg->blkg), ##args);
+
+#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \
+ blk_add_trace_msg((cfqd)->queue, "%s " fmt, \
+ blkg_path(&(cfqg)->blkg), ##args); \
+
+#else
#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
+#define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do{}while(0);
+#endif
#define cfq_log(cfqd, fmt, args...) \
blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
@@ -812,6 +825,7 @@ cfq_group_service_tree_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
if (cfqg->nr_cfqq)
return;
+ cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
cfqg->on_st = false;
cfqd->nr_groups--;
st->total_weight -= cfqg->weight;
@@ -866,6 +880,9 @@ static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
cfqg->saved_serving_prio = cfqd->serving_prio;
} else
cfqg->saved_workload_slice = 0;
+
+ cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
+ st->min_vdisktime);
}
#ifdef CONFIG_CFQ_GROUP_IOSCHED
--
1.6.2.5
o Export disk time and sector used by a group to user space through cgroup
interface.
o Also export a "dequeue" interface to cgroup which keeps track of how many
a times a group was deleted from service tree. Helps in debugging.
Signed-off-by: Vivek Goyal <[email protected]>
---
block/blk-cgroup.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++-
block/blk-cgroup.h | 22 ++++++++++++++++-
block/cfq-iosched.c | 23 ++++++++++++++----
3 files changed, 101 insertions(+), 8 deletions(-)
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 6bc99a3..4ef78d3 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -11,6 +11,8 @@
* Nauman Rafique <[email protected]>
*/
#include <linux/ioprio.h>
+#include <linux/seq_file.h>
+#include <linux/kdev_t.h>
#include "blk-cgroup.h"
extern void cfq_unlink_blkio_group(void *, struct blkio_group *);
@@ -23,8 +25,15 @@ struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup)
struct blkio_cgroup, css);
}
+void blkiocg_update_blkio_group_stats(struct blkio_group *blkg,
+ unsigned long time, unsigned long sectors)
+{
+ blkg->time += time;
+ blkg->sectors += sectors;
+}
+
void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
- struct blkio_group *blkg, void *key)
+ struct blkio_group *blkg, void *key, dev_t dev)
{
unsigned long flags;
@@ -37,6 +46,7 @@ void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
/* Need to take css reference ? */
cgroup_path(blkcg->css.cgroup, blkg->path, sizeof(blkg->path));
#endif
+ blkg->dev = dev;
}
static void __blkiocg_del_blkio_group(struct blkio_group *blkg)
@@ -115,12 +125,64 @@ blkiocg_weight_write(struct cgroup *cgroup, struct cftype *cftype, u64 val)
return 0;
}
+#define SHOW_FUNCTION_PER_GROUP(__VAR) \
+static int blkiocg_##__VAR##_read(struct cgroup *cgroup, \
+ struct cftype *cftype, struct seq_file *m) \
+{ \
+ struct blkio_cgroup *blkcg; \
+ struct blkio_group *blkg; \
+ struct hlist_node *n; \
+ \
+ if (!cgroup_lock_live_group(cgroup)) \
+ return -ENODEV; \
+ \
+ blkcg = cgroup_to_blkio_cgroup(cgroup); \
+ rcu_read_lock(); \
+ hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) {\
+ if (blkg->dev) \
+ seq_printf(m, "%u:%u %lu\n", MAJOR(blkg->dev), \
+ MINOR(blkg->dev), blkg->__VAR); \
+ } \
+ rcu_read_unlock(); \
+ cgroup_unlock(); \
+ return 0; \
+}
+
+SHOW_FUNCTION_PER_GROUP(time);
+SHOW_FUNCTION_PER_GROUP(sectors);
+#ifdef CONFIG_DEBUG_BLK_CGROUP
+SHOW_FUNCTION_PER_GROUP(dequeue);
+#endif
+#undef SHOW_FUNCTION_PER_GROUP
+
+#ifdef CONFIG_DEBUG_BLK_CGROUP
+void blkiocg_update_blkio_group_dequeue_stats(struct blkio_group *blkg,
+ unsigned long dequeue)
+{
+ blkg->dequeue += dequeue;
+}
+#endif
+
struct cftype blkio_files[] = {
{
.name = "weight",
.read_u64 = blkiocg_weight_read,
.write_u64 = blkiocg_weight_write,
},
+ {
+ .name = "time",
+ .read_seq_string = blkiocg_time_read,
+ },
+ {
+ .name = "sectors",
+ .read_seq_string = blkiocg_sectors_read,
+ },
+#ifdef CONFIG_DEBUG_BLK_CGROUP
+ {
+ .name = "dequeue",
+ .read_seq_string = blkiocg_dequeue_read,
+ },
+#endif
};
static int blkiocg_populate(struct cgroup_subsys *subsys, struct cgroup *cgroup)
diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index 3573199..b24ab71 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -30,7 +30,15 @@ struct blkio_group {
#ifdef CONFIG_DEBUG_BLK_CGROUP
/* Store cgroup path */
char path[128];
+ /* How many times this group has been removed from service tree */
+ unsigned long dequeue;
#endif
+ /* The device MKDEV(major, minor), this group has been created for */
+ dev_t dev;
+
+ /* total disk time and nr sectors dispatched by this group */
+ unsigned long time;
+ unsigned long sectors;
};
#define BLKIO_WEIGHT_MIN 100
@@ -42,24 +50,30 @@ static inline char *blkg_path(struct blkio_group *blkg)
{
return blkg->path;
}
+void blkiocg_update_blkio_group_dequeue_stats(struct blkio_group *blkg,
+ unsigned long dequeue);
#else
static inline char *blkg_path(struct blkio_group *blkg) { return NULL; }
+static inline void blkiocg_update_blkio_group_dequeue_stats(
+ struct blkio_group *blkg, unsigned long dequeue) {}
#endif
#ifdef CONFIG_BLK_CGROUP
extern struct blkio_cgroup blkio_root_cgroup;
extern struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup);
extern void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
- struct blkio_group *blkg, void *key);
+ struct blkio_group *blkg, void *key, dev_t dev);
extern int blkiocg_del_blkio_group(struct blkio_group *blkg);
extern struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg,
void *key);
+void blkiocg_update_blkio_group_stats(struct blkio_group *blkg,
+ unsigned long time, unsigned long sectors);
#else
static inline struct blkio_cgroup *
cgroup_to_blkio_cgroup(struct cgroup *cgroup) { return NULL; }
static inline void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
- struct blkio_group *blkg, void *key)
+ struct blkio_group *blkg, void *key, dev_t dev)
{
}
@@ -68,5 +82,9 @@ blkiocg_del_blkio_group(struct blkio_group *blkg) { return 0; }
static inline struct blkio_group *
blkiocg_lookup_group(struct blkio_cgroup *blkcg, void *key) { return NULL; }
+static inline void blkiocg_update_blkio_group_stats(struct blkio_group *blkg,
+ unsigned long time, unsigned long sectors)
+{
+}
#endif
#endif /* _BLK_CGROUP_H */
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 005a8ee..4e1c673 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -142,6 +142,8 @@ struct cfq_queue {
struct cfq_rb_root *service_tree;
struct cfq_queue *new_cfqq;
struct cfq_group *cfqg;
+ /* Sectors dispatched in current dispatch round */
+ unsigned long nr_sectors;
};
/*
@@ -832,6 +834,7 @@ cfq_group_service_tree_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
if (!RB_EMPTY_NODE(&cfqg->rb_node))
cfq_rb_erase(&cfqg->rb_node, st);
cfqg->saved_workload_slice = 0;
+ blkiocg_update_blkio_group_dequeue_stats(&cfqg->blkg, 1);
}
static inline unsigned long cfq_cfqq_slice_usage(struct cfq_queue *cfqq)
@@ -858,12 +861,13 @@ static inline unsigned long cfq_cfqq_slice_usage(struct cfq_queue *cfqq)
slice_used = allocated_slice;
}
- cfq_log_cfqq(cfqq->cfqd, cfqq, "sl_used=%lu", slice_used);
+ cfq_log_cfqq(cfqq->cfqd, cfqq, "sl_used=%lu sect=%lu", slice_used,
+ cfqq->nr_sectors);
return slice_used;
}
static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
- unsigned long service)
+ unsigned long service, unsigned long sectors)
{
struct cfq_rb_root *st = &cfqd->grp_service_tree;
@@ -883,6 +887,7 @@ static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
st->min_vdisktime);
+ blkiocg_update_blkio_group_stats(&cfqg->blkg, service, sectors);
}
#ifdef CONFIG_CFQ_GROUP_IOSCHED
@@ -900,6 +905,8 @@ cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create)
struct cfq_group *cfqg = NULL;
void *key = cfqd;
int i, j;
+ unsigned int major, minor;
+ struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info;
/* Do we need to take this reference */
if (!css_tryget(&blkcg->css))
@@ -930,7 +937,9 @@ cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create)
atomic_set(&cfqg->ref, 1);
/* Add group onto cgroup list */
- blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd);
+ sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
+ blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd,
+ MKDEV(major, minor));
/* Add group on cfqd list */
hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
@@ -1467,6 +1476,7 @@ static void __cfq_set_active_queue(struct cfq_data *cfqd,
cfqq->dispatch_start = jiffies;
cfqq->slice_end = 0;
cfqq->slice_dispatch = 0;
+ cfqq->nr_sectors = 0;
cfq_clear_cfqq_wait_request(cfqq);
cfq_clear_cfqq_must_dispatch(cfqq);
@@ -1502,7 +1512,8 @@ __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
}
- cfq_group_served(cfqd, cfqq->cfqg, cfq_cfqq_slice_usage(cfqq));
+ cfq_group_served(cfqd, cfqq->cfqg, cfq_cfqq_slice_usage(cfqq),
+ cfqq->nr_sectors);
if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
cfq_del_cfqq_rr(cfqd, cfqq);
@@ -1815,6 +1826,7 @@ static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
if (cfq_cfqq_sync(cfqq))
cfqd->sync_flight++;
+ cfqq->nr_sectors += blk_rq_sectors(rq);
}
/*
@@ -3509,7 +3521,8 @@ static void *cfq_init_queue(struct request_queue *q)
* to make sure that cfq_put_cfqg() does not try to kfree root group
*/
atomic_set(&cfqg->ref, 1);
- blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg, (void *)cfqd);
+ blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg, (void *)cfqd,
+ 0);
#endif
/*
* Not strictly needed (since RB_ROOT just clears the node and we
--
1.6.2.5
o Do not allow following three operations across groups for isolation.
- selection of co-operating queues
- preemtpions across groups
- request merging across groups.
Signed-off-by: Vivek Goyal <[email protected]>
---
block/cfq-iosched.c | 10 ++++++++++
1 files changed, 10 insertions(+), 0 deletions(-)
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 4e1c673..21121ce 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1449,6 +1449,9 @@ static int cfq_allow_merge(struct request_queue *q, struct request *rq,
struct cfq_io_context *cic;
struct cfq_queue *cfqq;
+ /* Deny merge if bio and rq don't belong to same cfq group */
+ if ((RQ_CFQQ(rq))->cfqg != cfq_get_cfqg(cfqd, 0))
+ return false;
/*
* Disallow merge of a sync bio into an async request.
*/
@@ -1694,6 +1697,10 @@ static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
if (!cfqq)
return NULL;
+ /* If new queue belongs to different cfq_group, don't choose it */
+ if (cur_cfqq->cfqg != cfqq->cfqg)
+ return NULL;
+
/*
* It only makes sense to merge sync queues.
*/
@@ -2962,6 +2969,9 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
if (!cfqq)
return false;
+ if (new_cfqq->cfqg != cfqq->cfqg)
+ return false;
+
if (cfq_slice_used(cfqq))
return true;
--
1.6.2.5
o If a task changes cgroup, drop reference to the cfqq associated with io
context and set cfqq pointer stored in ioc to NULL so that upon next request
arrival we will allocate a new queue in new group.
Signed-off-by: Vivek Goyal <[email protected]>
---
block/cfq-iosched.c | 39 +++++++++++++++++++++++++++++++++++++++
1 files changed, 39 insertions(+), 0 deletions(-)
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 21121ce..a9c8a52 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -2624,6 +2624,41 @@ static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
cfqq->pid = pid;
}
+#ifdef CONFIG_CFQ_GROUP_IOSCHED
+static void changed_cgroup(struct io_context *ioc, struct cfq_io_context *cic)
+{
+ struct cfq_queue *sync_cfqq = cic_to_cfqq(cic, 1);
+ struct cfq_data *cfqd = cic->key;
+ unsigned long flags;
+ struct request_queue *q;
+
+ if (unlikely(!cfqd))
+ return;
+
+ q = cfqd->queue;
+
+ spin_lock_irqsave(q->queue_lock, flags);
+
+ if (sync_cfqq) {
+ /*
+ * Drop reference to sync queue. A new sync queue will be
+ * assigned in new group upon arrival of a fresh request.
+ */
+ cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup");
+ cic_set_cfqq(cic, NULL, 1);
+ cfq_put_queue(sync_cfqq);
+ }
+
+ spin_unlock_irqrestore(q->queue_lock, flags);
+}
+
+static void cfq_ioc_set_cgroup(struct io_context *ioc)
+{
+ call_for_each_cic(ioc, changed_cgroup);
+ ioc->cgroup_changed = 0;
+}
+#endif /* CONFIG_CFQ_GROUP_IOSCHED */
+
static struct cfq_queue *
cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync,
struct io_context *ioc, gfp_t gfp_mask)
@@ -2856,6 +2891,10 @@ out:
if (unlikely(ioc->ioprio_changed))
cfq_ioc_set_ioprio(ioc);
+#ifdef CONFIG_CFQ_GROUP_IOSCHED
+ if (unlikely(ioc->cgroup_changed))
+ cfq_ioc_set_cgroup(ioc);
+#endif
return cic;
err_free:
cfq_cic_free(cic);
--
1.6.2.5
o Propagate blkio cgroup weight updation to associated cfq groups.
Signed-off-by: Vivek Goyal <[email protected]>
---
block/blk-cgroup.c | 7 +++++++
block/cfq-iosched.c | 6 ++++++
2 files changed, 13 insertions(+), 0 deletions(-)
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 4ef78d3..179ddfa 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -16,6 +16,7 @@
#include "blk-cgroup.h"
extern void cfq_unlink_blkio_group(void *, struct blkio_group *);
+extern void cfq_update_blkio_group_weight(struct blkio_group *, unsigned int);
struct blkio_cgroup blkio_root_cgroup = { .weight = 2*BLKIO_WEIGHT_DEFAULT };
@@ -116,12 +117,18 @@ static int
blkiocg_weight_write(struct cgroup *cgroup, struct cftype *cftype, u64 val)
{
struct blkio_cgroup *blkcg;
+ struct blkio_group *blkg;
+ struct hlist_node *n;
if (val < BLKIO_WEIGHT_MIN || val > BLKIO_WEIGHT_MAX)
return -EINVAL;
blkcg = cgroup_to_blkio_cgroup(cgroup);
+ spin_lock_irq(&blkcg->lock);
blkcg->weight = (unsigned int)val;
+ hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node)
+ cfq_update_blkio_group_weight(blkg, blkcg->weight);
+ spin_unlock_irq(&blkcg->lock);
return 0;
}
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index a9c8a52..5feffdc 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -898,6 +898,12 @@ static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg)
return NULL;
}
+void
+cfq_update_blkio_group_weight(struct blkio_group *blkg, unsigned int weight)
+{
+ cfqg_of_blkg(blkg)->weight = weight;
+}
+
static struct cfq_group *
cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create)
{
--
1.6.2.5
o If a group is not continuously backlogged, then it will be deleted from
service tree and loose it share. For example, if a single random seeky
reader or a single sequential reader is running in group.
o One solution is to let group loose it share if it is not backlogged and
other solution is to wait a bit for the slow group so that it can get its
time slice. This patch implements waiting for a group to wait a bit.
o This waiting is disabled for NCQ SSDs.
o This patch also intorduces the tunable "group_idle" which can enable/disable
group idling manually.
Signed-off-by: Vivek Goyal <[email protected]>
---
block/cfq-iosched.c | 142 ++++++++++++++++++++++++++++++++++-----------------
1 files changed, 95 insertions(+), 47 deletions(-)
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 5feffdc..557cce5 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -265,6 +265,7 @@ struct cfq_data {
unsigned int cfq_slice_async_rq;
unsigned int cfq_slice_idle;
unsigned int cfq_latency;
+ unsigned int cfq_group_idle;
struct list_head cic_list;
@@ -890,6 +891,37 @@ static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
blkiocg_update_blkio_group_stats(&cfqg->blkg, service, sectors);
}
+/*
+ * Determine whether we should enforce idle window for this queue.
+ */
+
+static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
+{
+ enum wl_prio_t prio = cfqq_prio(cfqq);
+ struct cfq_rb_root *service_tree = cfqq->service_tree;
+
+ /* We never do for idle class queues. */
+ if (prio == IDLE_WORKLOAD)
+ return false;
+
+ /* We do for queues that were marked with idle window flag. */
+ if (cfq_cfqq_idle_window(cfqq))
+ return true;
+
+ /*
+ * Otherwise, we do only if they are the last ones
+ * in their service tree.
+ */
+ if (!service_tree)
+ service_tree = service_tree_for(cfqq->cfqg, prio,
+ cfqq_type(cfqq), cfqd);
+
+ if (service_tree->count == 0)
+ return true;
+
+ return (service_tree->count == 1 && cfq_rb_first(service_tree) == cfqq);
+}
+
#ifdef CONFIG_CFQ_GROUP_IOSCHED
static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg)
{
@@ -1060,6 +1092,22 @@ void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg)
spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
}
+static inline bool cfqq_should_wait_busy(struct cfq_queue *cfqq)
+{
+ /* Group idling is disabled */
+ if (!cfqq->cfqd->cfq_group_idle)
+ return false;
+
+ /* cfqq group still has got more requests to dispatch */
+ if (!RB_EMPTY_ROOT(&cfqq->sort_list) || cfqq->cfqg->nr_cfqq > 1)
+ return false;
+
+ if (!cfq_should_idle(cfqq->cfqd, cfqq))
+ return false;
+
+ return true;
+}
+
#else /* GROUP_IOSCHED */
static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
{
@@ -1072,6 +1120,10 @@ cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
static void cfq_release_cfq_groups(struct cfq_data *cfqd) {}
static inline void cfq_put_cfqg(struct cfq_group *cfqg) {}
+static inline bool cfqq_should_wait_busy(struct cfq_queue *cfqq)
+{
+ return false;
+}
#endif /* GROUP_IOSCHED */
@@ -1724,51 +1776,24 @@ static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
return cfqq;
}
-/*
- * Determine whether we should enforce idle window for this queue.
- */
-
-static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
-{
- enum wl_prio_t prio = cfqq_prio(cfqq);
- struct cfq_rb_root *service_tree = cfqq->service_tree;
-
- /* We never do for idle class queues. */
- if (prio == IDLE_WORKLOAD)
- return false;
-
- /* We do for queues that were marked with idle window flag. */
- if (cfq_cfqq_idle_window(cfqq))
- return true;
-
- /*
- * Otherwise, we do only if they are the last ones
- * in their service tree.
- */
- if (!service_tree)
- service_tree = service_tree_for(cfqq->cfqg, prio,
- cfqq_type(cfqq), cfqd);
-
- if (service_tree->count == 0)
- return true;
-
- return (service_tree->count == 1 && cfq_rb_first(service_tree) == cfqq);
-}
-
-static void cfq_arm_slice_timer(struct cfq_data *cfqd)
+static bool cfq_arm_slice_timer(struct cfq_data *cfqd, int wait_busy)
{
struct cfq_queue *cfqq = cfqd->active_queue;
struct cfq_io_context *cic;
unsigned long sl;
struct cfq_rb_root *st;
+ /* If idle timer is already armed, nothing to do */
+ if (wait_busy && timer_pending(&cfqd->idle_slice_timer))
+ return true;
+
/*
* SSD device without seek penalty, disable idling. But only do so
* for devices that support queuing, otherwise we still have a problem
* with sync vs async workloads.
*/
if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
- return;
+ return false;
WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
WARN_ON(cfq_cfqq_slice_new(cfqq));
@@ -1777,29 +1802,29 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd)
* idle is disabled, either manually or by past process history
*/
if (!cfqd->cfq_slice_idle || !cfq_should_idle(cfqd, cfqq))
- return;
+ return false;
/*
* still requests with the driver, don't idle
*/
- if (rq_in_driver(cfqd))
- return;
+ if (rq_in_driver(cfqd) && !wait_busy)
+ return false;
/*
* task has exited, don't wait
*/
cic = cfqd->active_cic;
if (!cic || !atomic_read(&cic->ioc->nr_tasks))
- return;
+ return false;
/*
* If our average think time is larger than the remaining time
* slice, then don't idle. This avoids overrunning the allotted
* time slice.
*/
- if (sample_valid(cic->ttime_samples) &&
+ if (!wait_busy && sample_valid(cic->ttime_samples) &&
(cfqq->slice_end - jiffies < cic->ttime_mean))
- return;
+ return false;
cfq_mark_cfqq_wait_request(cfqq);
@@ -1812,14 +1837,19 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd)
*/
st = service_tree_for(cfqq->cfqg, cfqd->serving_prio,
SYNC_NOIDLE_WORKLOAD, cfqd);
- if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD && st->count > 0) {
+ if (!wait_busy && cfqd->serving_type == SYNC_NOIDLE_WORKLOAD
+ && st->count > 0) {
if (blk_queue_nonrot(cfqd->queue) || cfqd->hw_tag)
- return;
+ return false;
sl = min(sl, msecs_to_jiffies(CFQ_MIN_TT));
}
+ if (wait_busy)
+ sl = min(sl, msecs_to_jiffies(CFQ_MIN_TT));
+
mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
- cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl);
+ cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu wait_busy=%d", sl, wait_busy);
+ return true;
}
/*
@@ -2076,6 +2106,7 @@ static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
if (!cfqd->rq_queued)
return NULL;
+
/*
* The active queue has run out of time, expire it and select new.
*/
@@ -2114,6 +2145,16 @@ static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
}
expire:
+ /*
+ * Wait for a group to get busy before we expire it. No wait
+ * is done for NCQ SSDs. Do a small wait of 2ms on rotational
+ * media in the hope that group will get backlogged again and
+ * not loose its fair share.
+ */
+ if (cfqq_should_wait_busy(cfqq) && cfq_arm_slice_timer(cfqd, 1)) {
+ cfqq = NULL;
+ goto keep_queue;
+ }
cfq_slice_expired(cfqd, 0);
new_queue:
/*
@@ -3119,9 +3160,9 @@ cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
cfqd->busy_queues > 1) {
del_timer(&cfqd->idle_slice_timer);
- __blk_run_queue(cfqd->queue);
- }
- cfq_mark_cfqq_must_dispatch(cfqq);
+ __blk_run_queue(cfqd->queue);
+ } else
+ cfq_mark_cfqq_must_dispatch(cfqq);
}
} else if (cfq_should_preempt(cfqd, cfqq, rq)) {
/*
@@ -3231,10 +3272,13 @@ static void cfq_completed_request(struct request_queue *q, struct request *rq)
* of idling.
*/
if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
- cfq_slice_expired(cfqd, 1);
+ if (!cfqq_should_wait_busy(cfqq))
+ cfq_slice_expired(cfqd, 0);
+ else
+ cfq_arm_slice_timer(cfqd, 1);
else if (cfqq_empty && !cfq_close_cooperator(cfqd, cfqq) &&
sync && !rq_noidle(rq))
- cfq_arm_slice_timer(cfqd);
+ cfq_arm_slice_timer(cfqd, 0);
}
if (!rq_in_driver(cfqd))
@@ -3616,6 +3660,7 @@ static void *cfq_init_queue(struct request_queue *q)
cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
cfqd->cfq_slice_idle = cfq_slice_idle;
cfqd->cfq_latency = 1;
+ cfqd->cfq_group_idle = 1;
cfqd->hw_tag = 1;
cfqd->last_end_sync_rq = jiffies;
return cfqd;
@@ -3686,6 +3731,7 @@ SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
+SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 0);
#undef SHOW_FUNCTION
#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
@@ -3718,6 +3764,7 @@ STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
UINT_MAX, 0);
STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
+STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, 1, 0);
#undef STORE_FUNCTION
#define CFQ_ATTR(name) \
@@ -3734,6 +3781,7 @@ static struct elv_fs_entry cfq_attrs[] = {
CFQ_ATTR(slice_async_rq),
CFQ_ATTR(slice_idle),
CFQ_ATTR(low_latency),
+ CFQ_ATTR(group_idle),
__ATTR_NULL
};
--
1.6.2.5
Signed-off-by: Vivek Goyal <[email protected]>
---
Documentation/cgroups/blkio-controller.txt | 100 ++++++++++++++++++++++++++++
1 files changed, 100 insertions(+), 0 deletions(-)
create mode 100644 Documentation/cgroups/blkio-controller.txt
diff --git a/Documentation/cgroups/blkio-controller.txt b/Documentation/cgroups/blkio-controller.txt
new file mode 100644
index 0000000..6fb772f
--- /dev/null
+++ b/Documentation/cgroups/blkio-controller.txt
@@ -0,0 +1,100 @@
+ Block IO Controller
+ ===================
+Overview
+========
+cgroup subsys "blkio" implements the block io controller. There seems to be
+a need of various kind of IO control policies (like proportional BW, max BW)
+both at leaf nodes as well as at intermediate nodes in storage hierarchy. Plan
+is to use same cgroup based management interface for blkio controller and
+based on user options switch IO policies in the background.
+
+In the first phase, this patchset implements proportional weight time based
+division of disk policy. It is implemented in CFQ. Hence this policy takes
+effect only on leaf nodes when CFQ is being used.
+
+HOWTO
+=====
+You can do a very simple testing of running two dd threads in two different
+cgroups. Here is what you can do.
+
+- Enable group scheduling in CFQ
+ CONFIG_CFQ_GROUP_IOSCHED=y
+
+- Compile and boot into kernel and mount IO controller (blkio).
+
+ mount -t cgroup -o blkio none /cgroup
+
+- Create two cgroups
+ mkdir -p /cgroup/test1/ /cgroup/test2
+
+- Set weights of group test1 and test2
+ echo 1000 > /cgroup/test1/blkio.weight
+ echo 500 > /cgroup/test2/blkio.weight
+
+- Create two same size files (say 512MB each) on same disk (file1, file2) and
+ launch two dd threads in different cgroup to read those files.
+
+ sync
+ echo 3 > /proc/sys/vm/drop_caches
+
+ dd if=/mnt/sdb/zerofile1 of=/dev/null &
+ echo $! > /cgroup/test1/tasks
+ cat /cgroup/test1/tasks
+
+ dd if=/mnt/sdb/zerofile2 of=/dev/null &
+ echo $! > /cgroup/test2/tasks
+ cat /cgroup/test2/tasks
+
+- At macro level, first dd should finish first. To get more precise data, keep
+ on looking at (with the help of script), at blkio.disk_time and
+ blkio.disk_sectors files of both test1 and test2 groups. This will tell how
+ much disk time (in milli seconds), each group got and how many secotors each
+ group dispatched to the disk. We provide fairness in terms of disk time, so
+ ideally io.disk_time of cgroups should be in proportion to the weight.
+
+Various user visible config options
+===================================
+CONFIG_CFQ_GROUP_IOSCHED
+ - Enables group scheduling in CFQ. Currently only 1 level of group
+ creation is allowed.
+
+CONFIG_DEBUG_CFQ_IOSCHED
+ - Enables some debugging messages in blktrace. Also creates extra
+ cgroup file blkio.dequeue.
+
+Config options selected automatically
+=====================================
+These config options are not user visible and are selected/deselected
+automatically based on IO scheduler configuration.
+
+CONFIG_BLK_CGROUP
+ - Block IO controller. Selected by CONFIG_CFQ_GROUP_IOSCHED.
+
+CONFIG_DEBUG_BLK_CGROUP
+ - Debug help. Selected by CONFIG_DEBUG_CFQ_IOSCHED.
+
+Details of cgroup files
+=======================
+- blkio.weight
+ - Specifies per cgroup weight.
+
+ Currently allowed range of weights is from 100 to 1000.
+
+- blkio.time
+ - disk time allocated to cgroup per device in milliseconds. First
+ two fields specify the major and minor number of the device and
+ third field specifies the disk time allocated to group in
+ milliseconds.
+
+- blkio.sectors
+ - number of sectors transferred to/from disk by the group. First
+ two fields specify the major and minor number of the device and
+ third field specifies the number of sectors transferred by the
+ group to/from the device.
+
+- blkio.dequeue
+ - Debugging aid only enabled if CONFIG_DEBUG_CFQ_IOSCHED=y. This
+ gives the statistics about how many a times a group was dequeued
+ from service tree of the device. First two fields specify the major
+ and minor number of the device and third field specifies the number
+ of times a group was dequeued from a particular device.
--
1.6.2.5
On Fri, Nov 13, 2009 at 12:40:03PM -0500, Vivek Goyal wrote:
> o So far we had 300ms soft target latency system wide. Now with the
> introduction of cfq groups, divide that latency by number of groups so
> that one can come up with group target latency which will be helpful
> in determining the workload slice with-in group and also the dynamic
> slice length of the cfq queue.
>
> Signed-off-by: Vivek Goyal <[email protected]>
Regenerated the patch with group_target_lat renamed to group_slice.
Corrado mentioned that group_target_lat can be confusing here.
o So far we had 300ms soft target latency system wide. Now with the
introduction of cfq groups, divide that latency by number of groups so
that one can come up with group target latency which will be helpful
in determining the workload slice with-in group and also the dynamic
slice length of the cfq queue.
Signed-off-by: Vivek Goyal <[email protected]>
---
block/cfq-iosched.c | 65 ++++++++++++++++++++++++++++++++++++----------------
1 file changed, 45 insertions(+), 20 deletions(-)
Index: linux7/block/cfq-iosched.c
===================================================================
--- linux7.orig/block/cfq-iosched.c 2009-11-13 12:03:54.000000000 -0500
+++ linux7/block/cfq-iosched.c 2009-11-16 07:47:12.000000000 -0500
@@ -78,6 +78,7 @@ struct cfq_rb_root {
struct rb_node *left;
unsigned count;
u64 min_vdisktime;
+ unsigned total_weight;
};
#define CFQ_RB_ROOT (struct cfq_rb_root) { RB_ROOT, NULL, 0, 0, }
@@ -167,6 +168,8 @@ struct cfq_group {
/* number of cfqq currently on this group */
int nr_cfqq;
+ /* Per group busy queus average. Useful for workload slice calc. */
+ unsigned int busy_queues_avg[2];
/*
* rr lists of queues with requests, onle rr for each priority class.
* Counts are embedded in the cfq_rb_root
@@ -184,6 +187,8 @@ struct cfq_data {
/* Root service tree for cfq_groups */
struct cfq_rb_root grp_service_tree;
struct cfq_group root_group;
+ /* Number of active cfq groups on group service tree */
+ int nr_groups;
/*
* The priority currently being served
@@ -201,7 +206,6 @@ struct cfq_data {
struct rb_root prio_trees[CFQ_PRIO_LISTS];
unsigned int busy_queues;
- unsigned int busy_queues_avg[2];
int rq_in_driver[2];
int sync_flight;
@@ -330,10 +334,10 @@ static enum wl_type_t cfqq_type(struct c
return SYNC_WORKLOAD;
}
-static inline int cfq_busy_queues_wl(enum wl_prio_t wl, struct cfq_data *cfqd)
+static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl,
+ struct cfq_data *cfqd,
+ struct cfq_group *cfqg)
{
- struct cfq_group *cfqg = &cfqd->root_group;
-
if (wl == IDLE_WORKLOAD)
return cfqg->service_tree_idle.count;
@@ -420,18 +424,27 @@ cfq_prio_to_slice(struct cfq_data *cfqd,
* to quickly follows sudden increases and decrease slowly
*/
-static inline unsigned cfq_get_avg_queues(struct cfq_data *cfqd, bool rt)
+static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
+ struct cfq_group *cfqg, bool rt)
{
unsigned min_q, max_q;
unsigned mult = cfq_hist_divisor - 1;
unsigned round = cfq_hist_divisor / 2;
- unsigned busy = cfq_busy_queues_wl(rt, cfqd);
+ unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
- min_q = min(cfqd->busy_queues_avg[rt], busy);
- max_q = max(cfqd->busy_queues_avg[rt], busy);
- cfqd->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
+ min_q = min(cfqg->busy_queues_avg[rt], busy);
+ max_q = max(cfqg->busy_queues_avg[rt], busy);
+ cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
cfq_hist_divisor;
- return cfqd->busy_queues_avg[rt];
+ return cfqg->busy_queues_avg[rt];
+}
+
+static inline unsigned
+cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
+{
+ struct cfq_rb_root *st = &cfqd->grp_service_tree;
+
+ return cfq_target_latency * cfqg->weight / st->total_weight;
}
static inline void
@@ -439,12 +452,17 @@ cfq_set_prio_slice(struct cfq_data *cfqd
{
unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
if (cfqd->cfq_latency) {
- /* interested queues (we consider only the ones with the same
- * priority class) */
- unsigned iq = cfq_get_avg_queues(cfqd, cfq_class_rt(cfqq));
+ /*
+ * interested queues (we consider only the ones with the same
+ * priority class in the cfq group)
+ */
+ unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
+ cfq_class_rt(cfqq));
unsigned sync_slice = cfqd->cfq_slice[1];
unsigned expect_latency = sync_slice * iq;
- if (expect_latency > cfq_target_latency) {
+ unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
+
+ if (expect_latency > group_slice) {
unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
/* scale low_slice according to IO priority
* and sync vs async */
@@ -452,7 +470,7 @@ cfq_set_prio_slice(struct cfq_data *cfqd
min(slice, base_low_slice * slice / sync_slice);
/* the adapted slice value is scaled to fit all iqs
* into the target latency */
- slice = max(slice * cfq_target_latency / expect_latency,
+ slice = max(slice * group_slice / expect_latency,
low_slice);
}
}
@@ -707,6 +725,8 @@ cfq_group_service_tree_add(struct cfq_da
__cfq_group_service_tree_add(st, cfqg);
cfqg->on_st = true;
+ cfqd->nr_groups++;
+ st->total_weight += cfqg->weight;
}
static void
@@ -721,6 +741,8 @@ cfq_group_service_tree_del(struct cfq_da
return;
cfqg->on_st = false;
+ cfqd->nr_groups--;
+ st->total_weight -= cfqg->weight;
if (!RB_EMPTY_NODE(&cfqg->rb_node))
cfq_rb_erase(&cfqg->rb_node, st);
}
@@ -1592,6 +1614,7 @@ static void choose_service_tree(struct c
unsigned slice;
unsigned count;
struct cfq_rb_root *st;
+ unsigned group_slice;
if (!cfqg) {
cfqd->serving_prio = IDLE_WORKLOAD;
@@ -1600,9 +1623,9 @@ static void choose_service_tree(struct c
}
/* Choose next priority. RT > BE > IDLE */
- if (cfq_busy_queues_wl(RT_WORKLOAD, cfqd))
+ if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
cfqd->serving_prio = RT_WORKLOAD;
- else if (cfq_busy_queues_wl(BE_WORKLOAD, cfqd))
+ else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
cfqd->serving_prio = BE_WORKLOAD;
else {
cfqd->serving_prio = IDLE_WORKLOAD;
@@ -1640,9 +1663,11 @@ static void choose_service_tree(struct c
* proportional to the number of queues in that workload, over
* all the queues in the same priority class
*/
- slice = cfq_target_latency * count /
- max_t(unsigned, cfqd->busy_queues_avg[cfqd->serving_prio],
- cfq_busy_queues_wl(cfqd->serving_prio, cfqd));
+ group_slice = cfq_group_slice(cfqd, cfqg);
+
+ slice = group_slice * count /
+ max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio],
+ cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg));
if (cfqd->serving_type == ASYNC_WORKLOAD)
/* async workload slice is scaled down according to
> ---
> block/cfq-iosched.c | 65 +++++++++++++++++++++++++++++++++++---------------
> 1 files changed, 45 insertions(+), 20 deletions(-)
>
> diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
> index 73d93af..11256c3 100644
> --- a/block/cfq-iosched.c
> +++ b/block/cfq-iosched.c
> @@ -78,6 +78,7 @@ struct cfq_rb_root {
> struct rb_node *left;
> unsigned count;
> u64 min_vdisktime;
> + unsigned total_weight;
> };
> #define CFQ_RB_ROOT (struct cfq_rb_root) { RB_ROOT, NULL, 0, 0, }
>
> @@ -167,6 +168,8 @@ struct cfq_group {
> /* number of cfqq currently on this group */
> int nr_cfqq;
>
> + /* Per group busy queus average. Useful for workload slice calc. */
> + unsigned int busy_queues_avg[2];
> /*
> * rr lists of queues with requests, onle rr for each priority class.
> * Counts are embedded in the cfq_rb_root
> @@ -184,6 +187,8 @@ struct cfq_data {
> /* Root service tree for cfq_groups */
> struct cfq_rb_root grp_service_tree;
> struct cfq_group root_group;
> + /* Number of active cfq groups on group service tree */
> + int nr_groups;
>
> /*
> * The priority currently being served
> @@ -201,7 +206,6 @@ struct cfq_data {
> struct rb_root prio_trees[CFQ_PRIO_LISTS];
>
> unsigned int busy_queues;
> - unsigned int busy_queues_avg[2];
>
> int rq_in_driver[2];
> int sync_flight;
> @@ -330,10 +334,10 @@ static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
> return SYNC_WORKLOAD;
> }
>
> -static inline int cfq_busy_queues_wl(enum wl_prio_t wl, struct cfq_data *cfqd)
> +static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl,
> + struct cfq_data *cfqd,
> + struct cfq_group *cfqg)
> {
> - struct cfq_group *cfqg = &cfqd->root_group;
> -
> if (wl == IDLE_WORKLOAD)
> return cfqg->service_tree_idle.count;
>
> @@ -420,18 +424,27 @@ cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
> * to quickly follows sudden increases and decrease slowly
> */
>
> -static inline unsigned cfq_get_avg_queues(struct cfq_data *cfqd, bool rt)
> +static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
> + struct cfq_group *cfqg, bool rt)
> {
> unsigned min_q, max_q;
> unsigned mult = cfq_hist_divisor - 1;
> unsigned round = cfq_hist_divisor / 2;
> - unsigned busy = cfq_busy_queues_wl(rt, cfqd);
> + unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
>
> - min_q = min(cfqd->busy_queues_avg[rt], busy);
> - max_q = max(cfqd->busy_queues_avg[rt], busy);
> - cfqd->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
> + min_q = min(cfqg->busy_queues_avg[rt], busy);
> + max_q = max(cfqg->busy_queues_avg[rt], busy);
> + cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
> cfq_hist_divisor;
> - return cfqd->busy_queues_avg[rt];
> + return cfqg->busy_queues_avg[rt];
> +}
> +
> +static inline unsigned
> +cfq_group_latency(struct cfq_data *cfqd, struct cfq_group *cfqg)
> +{
> + struct cfq_rb_root *st = &cfqd->grp_service_tree;
> +
> + return cfq_target_latency * cfqg->weight / st->total_weight;
> }
>
> static inline void
> @@ -439,12 +452,17 @@ cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
> {
> unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
> if (cfqd->cfq_latency) {
> - /* interested queues (we consider only the ones with the same
> - * priority class) */
> - unsigned iq = cfq_get_avg_queues(cfqd, cfq_class_rt(cfqq));
> + /*
> + * interested queues (we consider only the ones with the same
> + * priority class in the cfq group)
> + */
> + unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
> + cfq_class_rt(cfqq));
> unsigned sync_slice = cfqd->cfq_slice[1];
> unsigned expect_latency = sync_slice * iq;
> - if (expect_latency > cfq_target_latency) {
> + unsigned group_target_lat = cfq_group_latency(cfqd, cfqq->cfqg);
> +
> + if (expect_latency > group_target_lat) {
> unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
> /* scale low_slice according to IO priority
> * and sync vs async */
> @@ -452,7 +470,7 @@ cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
> min(slice, base_low_slice * slice / sync_slice);
> /* the adapted slice value is scaled to fit all iqs
> * into the target latency */
> - slice = max(slice * cfq_target_latency / expect_latency,
> + slice = max(slice * group_target_lat / expect_latency,
> low_slice);
> }
> }
> @@ -707,6 +725,8 @@ cfq_group_service_tree_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
>
> __cfq_group_service_tree_add(st, cfqg);
> cfqg->on_st = true;
> + cfqd->nr_groups++;
> + st->total_weight += cfqg->weight;
> }
>
> static void
> @@ -721,6 +741,8 @@ cfq_group_service_tree_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
> return;
>
> cfqg->on_st = false;
> + cfqd->nr_groups--;
> + st->total_weight -= cfqg->weight;
> if (!RB_EMPTY_NODE(&cfqg->rb_node))
> cfq_rb_erase(&cfqg->rb_node, st);
> }
> @@ -1592,6 +1614,7 @@ static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
> unsigned slice;
> unsigned count;
> struct cfq_rb_root *st;
> + int group_target_latency;
>
> if (!cfqg) {
> cfqd->serving_prio = IDLE_WORKLOAD;
> @@ -1600,9 +1623,9 @@ static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
> }
>
> /* Choose next priority. RT > BE > IDLE */
> - if (cfq_busy_queues_wl(RT_WORKLOAD, cfqd))
> + if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
> cfqd->serving_prio = RT_WORKLOAD;
> - else if (cfq_busy_queues_wl(BE_WORKLOAD, cfqd))
> + else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
> cfqd->serving_prio = BE_WORKLOAD;
> else {
> cfqd->serving_prio = IDLE_WORKLOAD;
> @@ -1640,9 +1663,11 @@ static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
> * proportional to the number of queues in that workload, over
> * all the queues in the same priority class
> */
> - slice = cfq_target_latency * count /
> - max_t(unsigned, cfqd->busy_queues_avg[cfqd->serving_prio],
> - cfq_busy_queues_wl(cfqd->serving_prio, cfqd));
> + group_target_latency = cfq_group_latency(cfqd, cfqg);
> +
> + slice = group_target_latency * count /
> + max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio],
> + cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg));
>
> if (cfqd->serving_type == ASYNC_WORKLOAD)
> /* async workload slice is scaled down according to
> --
> 1.6.2.5
Hi Vivek -
Some minor nit comments in this and the next three e-mails...
On Fri, 2009-11-13 at 12:40 -0500, Vivek Goyal wrote:
> @@ -1065,17 +1080,43 @@ static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
> * Get next queue for service. Unless we have a queue preemption,
> * we'll simply select the first cfqq in the service tree.
> */
> -static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
> +static struct cfq_queue *__cfq_get_next_queue(struct cfq_data *cfqd)
> {
> struct cfq_rb_root *service_tree =
> service_tree_for(cfqd->serving_group, cfqd->serving_prio,
> cfqd->serving_type, cfqd);
>
> + if (!cfqd->rq_queued)
> + return NULL;
> +
> if (RB_EMPTY_ROOT(&service_tree->rb))
> return NULL;
> return cfq_rb_first(service_tree);
> }
>
> +static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
> +{
> + struct cfq_group *cfqg = &cfqd->root_group;
> + struct cfq_queue *cfqq;
> + int i, j;
> +
> + if (!cfqd->rq_queued)
> + return NULL;
> +
> + for (i = 0; i < 2; ++i) {
> + for (j = 0; j < 3; ++j) {
Is this double for-loop a good candidate for an iterator macro
construct? (I think this is used 6 times in your total patch set.)
> + cfqq = cfq_rb_first(&cfqg->service_trees[i][j]);
> + if (cfqq)
> + return cfqq;
> + }
> + }
> +
Perhaps just change the 4 lines below with:
return cfq_rb_first(&cfgg->service_tree_idle);
to be consistent (e.g. right above in __cfq_get_next_queue) and for less
code clutter?
> + cfqq = cfq_rb_first(&cfqg->service_tree_idle);
> + if (cfqq)
> + return cfqq;
> + return NULL;
> +}
> +
On Fri, 2009-11-13 at 12:40 -0500, Vivek Goyal wrote:
> +
> +static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
> +{
> + s64 delta = (s64)(vdisktime - min_vdisktime);
> + if (delta > 0)
> + min_vdisktime = vdisktime;
> +
> + return min_vdisktime;
> +}
> +
> +static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
> +{
> + s64 delta = (s64)(vdisktime - min_vdisktime);
> + if (delta < 0)
> + min_vdisktime = vdisktime;
> +
> + return min_vdisktime;
> +}
> +
> +static void update_min_vdisktime(struct cfq_rb_root *st)
> +{
> + u64 vdisktime = st->min_vdisktime;
> + struct cfq_group *cfqg;
> +
> + if (st->active) {
> + cfqg = rb_entry(st->active, struct cfq_group, rb_node);
> + vdisktime = cfqg->vdisktime;
> + }
> +
> + if (st->left) {
> + cfqg = rb_entry(st->left, struct cfq_group, rb_node);
> + vdisktime = min_vdisktime(vdisktime, cfqg->vdisktime);
> + }
> +
> + st->min_vdisktime = max_vdisktime(st->min_vdisktime, vdisktime);
> +}
Any reason why you don't use min_t(u64, vdisktime, cfqg->vdisktime) and
max_t(u64, st->min_vdisktime, vdisktime)) here?
On Fri, 2009-11-13 at 12:40 -0500, Vivek Goyal wrote:
> o Determine the cgroup IO submitting task belongs to and create the cfq
> group if it does not exist already.
>
> o Also link cfqq and associated cfq group.
>
> o Currently all async IO is mapped to root group.
>
> Signed-off-by: Vivek Goyal <[email protected]>
> ---
> block/cfq-iosched.c | 113 ++++++++++++++++++++++++++++++++++++++++++++++-----
> 1 files changed, 102 insertions(+), 11 deletions(-)
>
> diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
> index 4c05d45..9653caf 100644
> --- a/block/cfq-iosched.c
> +++ b/block/cfq-iosched.c
> @@ -188,6 +188,10 @@ struct cfq_group {
> unsigned long saved_workload_slice;
> enum wl_type_t saved_workload;
> enum wl_prio_t saved_serving_prio;
> + struct blkio_group blkg;
> +#ifdef CONFIG_CFQ_GROUP_IOSCHED
> + struct hlist_node cfqd_node;
> +#endif
> };
>
> /*
> @@ -267,8 +271,13 @@ struct cfq_data {
> struct cfq_queue oom_cfqq;
>
> unsigned long last_end_sync_rq;
> +
> + /* List of cfq groups being managed on this device*/
> + struct hlist_head cfqg_list;
> };
>
> +static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
> +
> static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg,
> enum wl_prio_t prio,
> enum wl_type_t type,
> @@ -858,6 +867,91 @@ static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
> cfqg->saved_workload_slice = 0;
> }
>
> +#ifdef CONFIG_CFQ_GROUP_IOSCHED
> +static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg)
> +{
> + if (blkg)
> + return container_of(blkg, struct cfq_group, blkg);
> + return NULL;
> +}
> +
> +static struct cfq_group *
> +cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create)
> +{
> + struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
> + struct cfq_group *cfqg = NULL;
> + void *key = cfqd;
> + int i, j;
> +
> + /* Do we need to take this reference */
> + if (!css_tryget(&blkcg->css))
> + return NULL;;
> +
> + cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key));
> + if (cfqg || !create)
> + goto done;
> +
> + cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node);
> + if (!cfqg)
> + goto done;
> +
> + cfqg->weight = blkcg->weight;
> +
> + for (i = 0; i < 2; ++i)
> + for (j = 0; j < 3; ++j)
> + cfqg->service_trees[i][j] = CFQ_RB_ROOT;
> + cfqg->service_tree_idle = CFQ_RB_ROOT;
> + RB_CLEAR_NODE(&cfqg->rb_node);
> +
> + /* Add group onto cgroup list */
> + blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd);
> +
> + /* Add group on cfqd list */
> + hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
> +
> +done:
> + css_put(&blkcg->css);
> + return cfqg;
> +}
> +
> +/*
> + * Search for the cfq group current task belongs to. If create = 1, then also
> + * create the cfq group if it does not exist. request_queue lock must be held.
You might want to also note that if the creation fails, the root group
is used.
On Fri, 2009-11-13 at 12:40 -0500, Vivek Goyal wrote:
> Signed-off-by: Vivek Goyal <[email protected]>
> ---
> Documentation/cgroups/blkio-controller.txt | 100 ++++++++++++++++++++++++++++
> 1 files changed, 100 insertions(+), 0 deletions(-)
> create mode 100644 Documentation/cgroups/blkio-controller.txt
>
> diff --git a/Documentation/cgroups/blkio-controller.txt b/Documentation/cgroups/blkio-controller.txt
> new file mode 100644
> index 0000000..6fb772f
> --- /dev/null
> +++ b/Documentation/cgroups/blkio-controller.txt
> @@ -0,0 +1,100 @@
> + Block IO Controller
> + ===================
> +Overview
> +========
> +cgroup subsys "blkio" implements the block io controller. There seems to be
> +a need of various kind of IO control policies (like proportional BW, max BW)
Change to: "a need for various kinds"
> +both at leaf nodes as well as at intermediate nodes in storage hierarchy. Plan
Change to: "in a storage hierarchy"
> +is to use same cgroup based management interface for blkio controller and
Change to: "use the same cgroup"
> +based on user options switch IO policies in the background.
> +
> +In the first phase, this patchset implements proportional weight time based
> +division of disk policy. It is implemented in CFQ. Hence this policy takes
> +effect only on leaf nodes when CFQ is being used.
> +
> +HOWTO
> +=====
> +You can do a very simple testing of running two dd threads in two different
> +cgroups. Here is what you can do.
> +
> +- Enable group scheduling in CFQ
> + CONFIG_CFQ_GROUP_IOSCHED=y
> +
> +- Compile and boot into kernel and mount IO controller (blkio).
> +
> + mount -t cgroup -o blkio none /cgroup
> +
> +- Create two cgroups
> + mkdir -p /cgroup/test1/ /cgroup/test2
> +
> +- Set weights of group test1 and test2
> + echo 1000 > /cgroup/test1/blkio.weight
> + echo 500 > /cgroup/test2/blkio.weight
> +
> +- Create two same size files (say 512MB each) on same disk (file1, file2) and
> + launch two dd threads in different cgroup to read those files.
> +
> + sync
> + echo 3 > /proc/sys/vm/drop_caches
> +
> + dd if=/mnt/sdb/zerofile1 of=/dev/null &
> + echo $! > /cgroup/test1/tasks
> + cat /cgroup/test1/tasks
> +
> + dd if=/mnt/sdb/zerofile2 of=/dev/null &
> + echo $! > /cgroup/test2/tasks
> + cat /cgroup/test2/tasks
> +
> +- At macro level, first dd should finish first. To get more precise data, keep
> + on looking at (with the help of script), at blkio.disk_time and
Change to: "on looking at blkio.disk_time and"
> + blkio.disk_sectors files of both test1 and test2 groups. This will tell how
> + much disk time (in milli seconds), each group got and how many secotors each
Change to: "much disk time (in milliseconds) each group got and how many
sectors each"
> + group dispatched to the disk. We provide fairness in terms of disk time, so
> + ideally io.disk_time of cgroups should be in proportion to the weight.
Change to: "ideally the io.disk_time of each cgroup should be in
proportion to its weight."
Vivek Goyal wrote:
> Hi Jens,
>
> This is V3 of the Block IO controller patches on top of "for-2.6.33" branch
> of block tree.
>
...
Hi Vivek,
If an idle task is running group A and a normal task is running in group B, these
two group have the same weight, I think IO Controller should isolate group A and
group B, these two group should get 50% of the IO bw for each, right? But for this case,
we don't see any isolation, instead, group B monopolizes almost all IO BW. I guess
the major reason is idle cfqq is only allowed to dispatch one request and get expired.
I think in order to get better isolation, we shouldn't expire the idle cfqq immediately
if this idle queue is the only one this its group. The following patch enable idling
for idle queue and prevent expiring it immediately after dispatch one request if it's
the only one in group. This patch is working for V3, hasn't tested on V4 yet.
Signed-off-by: Gui Jianfeng <[email protected]>
---
block/cfq-iosched.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 6f9d019..3440837 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -900,7 +900,7 @@ static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
struct cfq_rb_root *service_tree = cfqq->service_tree;
/* We never do for idle class queues. */
- if (prio == IDLE_WORKLOAD)
+ if (prio == IDLE_WORKLOAD && cfqq->cfqg->nr_cfqq > 1)
return false;
/* We do for queues that were marked with idle window flag. */
@@ -2336,7 +2336,7 @@ static int cfq_dispatch_requests(struct request_queue *q, int force)
* expire an async queue immediately if it has used up its slice. idle
* queue always expire after 1 dispatch round.
*/
- if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
+ if (cfqq->cfqg->nr_cfqq > 1 && ((!cfq_cfqq_sync(cfqq) &&
cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
cfq_class_idle(cfqq))) {
cfqq->slice_end = jiffies + 1;
--
1.5.4.rc3
--
Regards
Gui Jianfeng
On Mon, Nov 30, 2009 at 03:29:52PM +0800, Gui Jianfeng wrote:
> Vivek Goyal wrote:
> > Hi Jens,
> >
> > This is V3 of the Block IO controller patches on top of "for-2.6.33" branch
> > of block tree.
> >
> ...
>
> Hi Vivek,
>
> If an idle task is running group A and a normal task is running in group B, these
> two group have the same weight, I think IO Controller should isolate group A and
> group B, these two group should get 50% of the IO bw for each, right? But for this case,
> we don't see any isolation, instead, group B monopolizes almost all IO BW. I guess
> the major reason is idle cfqq is only allowed to dispatch one request and get expired.
> I think in order to get better isolation, we shouldn't expire the idle cfqq immediately
> if this idle queue is the only one this its group. The following patch enable idling
> for idle queue and prevent expiring it immediately after dispatch one request if it's
> the only one in group. This patch is working for V3, hasn't tested on V4 yet.
>
Hi Gui,
Thanks for the patch. I have intentionally kept idle queue make dispatch
one request at a time system wide irrespective of group.
What's the use case scenario of enforcing idle dispatch more based on
group weight. If somebody has marked a queue idle, he is not expecting
much of that queue anyway.
Now one can argue that for better isolation, don't make idle class system
wide and an idle task should get more disk time if there are no other
queues with-in group.
So for the time being I will leave as it is. We can fix this once somebody
needs stronger isolation even for idle tasks.
Thanks
Vivek
> Signed-off-by: Gui Jianfeng <[email protected]>
> ---
> block/cfq-iosched.c | 4 ++--
> 1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
> index 6f9d019..3440837 100644
> --- a/block/cfq-iosched.c
> +++ b/block/cfq-iosched.c
> @@ -900,7 +900,7 @@ static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
> struct cfq_rb_root *service_tree = cfqq->service_tree;
>
> /* We never do for idle class queues. */
> - if (prio == IDLE_WORKLOAD)
> + if (prio == IDLE_WORKLOAD && cfqq->cfqg->nr_cfqq > 1)
> return false;
>
> /* We do for queues that were marked with idle window flag. */
> @@ -2336,7 +2336,7 @@ static int cfq_dispatch_requests(struct request_queue *q, int force)
> * expire an async queue immediately if it has used up its slice. idle
> * queue always expire after 1 dispatch round.
> */
> - if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
> + if (cfqq->cfqg->nr_cfqq > 1 && ((!cfq_cfqq_sync(cfqq) &&
> cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
> cfq_class_idle(cfqq))) {
> cfqq->slice_end = jiffies + 1;
> --
> 1.5.4.rc3
>
> --
> Regards
> Gui Jianfeng
Vivek Goyal wrote:
> On Mon, Nov 30, 2009 at 03:29:52PM +0800, Gui Jianfeng wrote:
>> Vivek Goyal wrote:
>>> Hi Jens,
>>>
>>> This is V3 of the Block IO controller patches on top of "for-2.6.33" branch
>>> of block tree.
>>>
>> ...
>>
>> Hi Vivek,
>>
>> If an idle task is running group A and a normal task is running in group B, these
>> two group have the same weight, I think IO Controller should isolate group A and
>> group B, these two group should get 50% of the IO bw for each, right? But for this case,
>> we don't see any isolation, instead, group B monopolizes almost all IO BW. I guess
>> the major reason is idle cfqq is only allowed to dispatch one request and get expired.
>> I think in order to get better isolation, we shouldn't expire the idle cfqq immediately
>> if this idle queue is the only one this its group. The following patch enable idling
>> for idle queue and prevent expiring it immediately after dispatch one request if it's
>> the only one in group. This patch is working for V3, hasn't tested on V4 yet.
>>
>
> Hi Gui,
>
> Thanks for the patch. I have intentionally kept idle queue make dispatch
> one request at a time system wide irrespective of group.
>
> What's the use case scenario of enforcing idle dispatch more based on
> group weight. If somebody has marked a queue idle, he is not expecting
> much of that queue anyway.
IMHO, If somebody decide to put an idle task into a group, i think he
should know what will happen(isolation thing).
>
> Now one can argue that for better isolation, don't make idle class system
> wide and an idle task should get more disk time if there are no other
> queues with-in group.
>
> So for the time being I will leave as it is. We can fix this once somebody
> needs stronger isolation even for idle tasks.
>
So, maybe we can rely on group_isolation tunable, when group_isolation == 1,
we provide isolation for idle queues.