2010-11-15 00:55:26

by Gui, Jianfeng/归 剑峰

Subject: [RFC] [PATCH 4/8] cfq-iosched: Get rid of st->active

When a cfq group is running, it won't be dequeued from service tree, so
there's no need to store the active one in st->active. Just gid rid of it.

Signed-off-by: Gui Jianfeng <[email protected]>
---
block/cfq-iosched.c | 15 +--------------
1 files changed, 1 insertions(+), 14 deletions(-)

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index ef88931..ad577b5 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -88,7 +88,6 @@ struct cfq_rb_root {
unsigned count;
unsigned total_weight;
u64 min_vdisktime;
- struct rb_node *active;
};
#define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, .left = NULL, \
.count = 0, .min_vdisktime = 0, }
@@ -599,11 +598,6 @@ static void update_min_vdisktime(struct cfq_rb_root *st)
u64 vdisktime = st->min_vdisktime;
struct io_sched_entity *entity;

- if (st->active) {
- entity = rb_entry_entity(st->active);
- vdisktime = entity->vdisktime;
- }
-
if (st->left) {
entity = rb_entry_entity(st->left);
vdisktime = min_vdisktime(vdisktime, entity->vdisktime);
@@ -925,9 +919,6 @@ cfq_group_service_tree_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
struct cfq_rb_root *st = &cfqd->grp_service_tree;
struct io_sched_entity *group_entity = &cfqg->group_entity;

- if (st->active == &group_entity->rb_node)
- st->active = NULL;
-
BUG_ON(cfqg->nr_cfqq < 1);
cfqg->nr_cfqq--;

@@ -1130,7 +1121,7 @@ static void cfq_put_cfqg(struct cfq_group *cfqg)
if (!atomic_dec_and_test(&cfqg->ref))
return;
for_each_cfqg_st(cfqg, i, j, st)
- BUG_ON(!RB_EMPTY_ROOT(&st->rb) || st->active != NULL);
+ BUG_ON(!RB_EMPTY_ROOT(&st->rb));
kfree(cfqg);
}

@@ -1773,9 +1764,6 @@ __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
if (cfqq == cfqd->active_queue)
cfqd->active_queue = NULL;

- if (&cfqq->cfqg->group_entity.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;
@@ -2305,7 +2293,6 @@ static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
group_entity = cfq_rb_first_entity(st);
cfqg = cfqg_of_entity(group_entity);
BUG_ON(!cfqg);
- st->active = &group_entity->rb_node;
update_min_vdisktime(st);
return cfqg;
}
--
1.6.5.2





--
Regards
Gui Jianfeng

2010-11-29 02:34:29

by Gui, Jianfeng/归 剑峰

Subject: Re: [RFC] [PATCH 4/8] cfq-iosched: Get rid of st->active

Vivek Goyal wrote:
> On Sun, Nov 14, 2010 at 04:25:04PM +0800, Gui Jianfeng wrote:
>> When a cfq group is running, it won't be dequeued from service tree, so
>> there's no need to store the active one in st->active. Just gid rid of it.
>>
>> Signed-off-by: Gui Jianfeng <[email protected]>
>
> Hmm..., once I was also wondering if ->active pointer is superflous. Looks
> like it is and st->left will always represent the element being served. I
> think this is more of a cleanup patch and can either be first patch in the
> series or you can post it independently.

Ok.

Gui

>
> Vivek
>
>> ---
>> block/cfq-iosched.c | 15 +--------------
>> 1 files changed, 1 insertions(+), 14 deletions(-)
>>
>> diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
>> index ef88931..ad577b5 100644
>> --- a/block/cfq-iosched.c
>> +++ b/block/cfq-iosched.c
>> @@ -88,7 +88,6 @@ struct cfq_rb_root {
>> unsigned count;
>> unsigned total_weight;
>> u64 min_vdisktime;
>> - struct rb_node *active;
>> };
>> #define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, .left = NULL, \
>> .count = 0, .min_vdisktime = 0, }
>> @@ -599,11 +598,6 @@ static void update_min_vdisktime(struct cfq_rb_root *st)
>> u64 vdisktime = st->min_vdisktime;
>> struct io_sched_entity *entity;
>>
>> - if (st->active) {
>> - entity = rb_entry_entity(st->active);
>> - vdisktime = entity->vdisktime;
>> - }
>> -
>> if (st->left) {
>> entity = rb_entry_entity(st->left);
>> vdisktime = min_vdisktime(vdisktime, entity->vdisktime);
>> @@ -925,9 +919,6 @@ cfq_group_service_tree_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
>> struct cfq_rb_root *st = &cfqd->grp_service_tree;
>> struct io_sched_entity *group_entity = &cfqg->group_entity;
>>
>> - if (st->active == &group_entity->rb_node)
>> - st->active = NULL;
>> -
>> BUG_ON(cfqg->nr_cfqq < 1);
>> cfqg->nr_cfqq--;
>>
>> @@ -1130,7 +1121,7 @@ static void cfq_put_cfqg(struct cfq_group *cfqg)
>> if (!atomic_dec_and_test(&cfqg->ref))
>> return;
>> for_each_cfqg_st(cfqg, i, j, st)
>> - BUG_ON(!RB_EMPTY_ROOT(&st->rb) || st->active != NULL);
>> + BUG_ON(!RB_EMPTY_ROOT(&st->rb));
>> kfree(cfqg);
>> }
>>
>> @@ -1773,9 +1764,6 @@ __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
>> if (cfqq == cfqd->active_queue)
>> cfqd->active_queue = NULL;
>>
>> - if (&cfqq->cfqg->group_entity.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;
>> @@ -2305,7 +2293,6 @@ static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
>> group_entity = cfq_rb_first_entity(st);
>> cfqg = cfqg_of_entity(group_entity);
>> BUG_ON(!cfqg);
>> - st->active = &group_entity->rb_node;
>> update_min_vdisktime(st);
>> return cfqg;
>> }
>> --
>> 1.6.5.2
>>
>>
>