From: Zhaoyang Huang <Zhaoyang [email protected]>
In previous implementation, the number of refault pages is used
for judging the refault period of each page, which is not precised.
We introduce the timestamp into the workingset's entry to measure
the file page's activity.
The patch is tested on an Android system, which can be described as
comparing the launch time of an application between a huge memory
consumption. The result is launch time decrease 50% and the page fault
during the test decrease 80%.
Signed-off-by: Zhaoyang Huang <[email protected]>
---
include/linux/mmzone.h | 2 ++
mm/workingset.c | 24 +++++++++++++++++-------
2 files changed, 19 insertions(+), 7 deletions(-)
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 32699b2..c38ba0a 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -240,6 +240,8 @@ struct lruvec {
atomic_long_t inactive_age;
/* Refaults at the time of last reclaim cycle */
unsigned long refaults;
+ atomic_long_t refaults_ratio;
+ atomic_long_t prev_fault;
#ifdef CONFIG_MEMCG
struct pglist_data *pgdat;
#endif
diff --git a/mm/workingset.c b/mm/workingset.c
index 40ee02c..6361853 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -159,7 +159,7 @@
NODES_SHIFT + \
MEM_CGROUP_ID_SHIFT)
#define EVICTION_MASK (~0UL >> EVICTION_SHIFT)
-
+#define EVICTION_JIFFIES (BITS_PER_LONG >> 3)
/*
* Eviction timestamps need to be able to cover the full range of
* actionable refaults. However, bits are tight in the radix tree
@@ -175,18 +175,22 @@ static void *pack_shadow(int memcgid, pg_data_t *pgdat, unsigned long eviction)
eviction >>= bucket_order;
eviction = (eviction << MEM_CGROUP_ID_SHIFT) | memcgid;
eviction = (eviction << NODES_SHIFT) | pgdat->node_id;
+ eviction = (eviction << EVICTION_JIFFIES) | (jiffies >> EVICTION_JIFFIES);
eviction = (eviction << RADIX_TREE_EXCEPTIONAL_SHIFT);
return (void *)(eviction | RADIX_TREE_EXCEPTIONAL_ENTRY);
}
static void unpack_shadow(void *shadow, int *memcgidp, pg_data_t **pgdat,
- unsigned long *evictionp)
+ unsigned long *evictionp, unsigned long *prev_jiffp)
{
unsigned long entry = (unsigned long)shadow;
int memcgid, nid;
+ unsigned long prev_jiff;
entry >>= RADIX_TREE_EXCEPTIONAL_SHIFT;
+ entry >>= EVICTION_JIFFIES;
+ prev_jiff = (entry & ((1UL << EVICTION_JIFFIES) - 1)) << EVICTION_JIFFIES;
nid = entry & ((1UL << NODES_SHIFT) - 1);
entry >>= NODES_SHIFT;
memcgid = entry & ((1UL << MEM_CGROUP_ID_SHIFT) - 1);
@@ -195,6 +199,7 @@ static void unpack_shadow(void *shadow, int *memcgidp, pg_data_t **pgdat,
*memcgidp = memcgid;
*pgdat = NODE_DATA(nid);
*evictionp = entry << bucket_order;
+ *prev_jiffp = prev_jiff;
}
/**
@@ -242,8 +247,12 @@ bool workingset_refault(void *shadow)
unsigned long refault;
struct pglist_data *pgdat;
int memcgid;
+ unsigned long refault_ratio;
+ unsigned long prev_jiff;
+ unsigned long avg_refault_time;
+ unsigned long refault_time;
- unpack_shadow(shadow, &memcgid, &pgdat, &eviction);
+ unpack_shadow(shadow, &memcgid, &pgdat, &eviction, &prev_jiff);
rcu_read_lock();
/*
@@ -288,10 +297,11 @@ bool workingset_refault(void *shadow)
* list is not a problem.
*/
refault_distance = (refault - eviction) & EVICTION_MASK;
-
inc_lruvec_state(lruvec, WORKINGSET_REFAULT);
-
- if (refault_distance <= active_file) {
+ lruvec->refaults_ratio = atomic_long_read(&lruvec->inactive_age) / jiffies;
+ refault_time = jiffies - prev_jiff;
+ avg_refault_time = refault_distance / lruvec->refaults_ratio;
+ if (refault_time <= avg_refault_time) {
inc_lruvec_state(lruvec, WORKINGSET_ACTIVATE);
rcu_read_unlock();
return true;
@@ -521,7 +531,7 @@ static int __init workingset_init(void)
* some more pages at runtime, so keep working with up to
* double the initial memory by using totalram_pages as-is.
*/
- timestamp_bits = BITS_PER_LONG - EVICTION_SHIFT;
+ timestamp_bits = BITS_PER_LONG - EVICTION_SHIFT - EVICTION_JIFFIES;
max_order = fls_long(totalram_pages - 1);
if (max_order > timestamp_bits)
bucket_order = max_order - timestamp_bits;
--
1.9.1
On Wed, Apr 3, 2019 at 7:03 PM Zhaoyang Huang <[email protected]> wrote:
>
> From: Zhaoyang Huang <Zhaoyang [email protected]>
>
> In previous implementation, the number of refault pages is used
> for judging the refault period of each page, which is not precised.
> We introduce the timestamp into the workingset's entry to measure
> the file page's activity.
>
> The patch is tested on an Android system, which can be described as
> comparing the launch time of an application between a huge memory
> consumption. The result is launch time decrease 50% and the page fault
> during the test decrease 80%.
>
> Signed-off-by: Zhaoyang Huang <[email protected]>
> ---
> include/linux/mmzone.h | 2 ++
> mm/workingset.c | 24 +++++++++++++++++-------
> 2 files changed, 19 insertions(+), 7 deletions(-)
>
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index 32699b2..c38ba0a 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -240,6 +240,8 @@ struct lruvec {
> atomic_long_t inactive_age;
> /* Refaults at the time of last reclaim cycle */
> unsigned long refaults;
> + atomic_long_t refaults_ratio;
> + atomic_long_t prev_fault;
> #ifdef CONFIG_MEMCG
> struct pglist_data *pgdat;
> #endif
> diff --git a/mm/workingset.c b/mm/workingset.c
> index 40ee02c..6361853 100644
> --- a/mm/workingset.c
> +++ b/mm/workingset.c
> @@ -159,7 +159,7 @@
> NODES_SHIFT + \
> MEM_CGROUP_ID_SHIFT)
> #define EVICTION_MASK (~0UL >> EVICTION_SHIFT)
> -
> +#define EVICTION_JIFFIES (BITS_PER_LONG >> 3)
> /*
> * Eviction timestamps need to be able to cover the full range of
> * actionable refaults. However, bits are tight in the radix tree
> @@ -175,18 +175,22 @@ static void *pack_shadow(int memcgid, pg_data_t *pgdat, unsigned long eviction)
> eviction >>= bucket_order;
> eviction = (eviction << MEM_CGROUP_ID_SHIFT) | memcgid;
> eviction = (eviction << NODES_SHIFT) | pgdat->node_id;
> + eviction = (eviction << EVICTION_JIFFIES) | (jiffies >> EVICTION_JIFFIES);
> eviction = (eviction << RADIX_TREE_EXCEPTIONAL_SHIFT);
>
> return (void *)(eviction | RADIX_TREE_EXCEPTIONAL_ENTRY);
> }
>
> static void unpack_shadow(void *shadow, int *memcgidp, pg_data_t **pgdat,
> - unsigned long *evictionp)
> + unsigned long *evictionp, unsigned long *prev_jiffp)
> {
> unsigned long entry = (unsigned long)shadow;
> int memcgid, nid;
> + unsigned long prev_jiff;
>
> entry >>= RADIX_TREE_EXCEPTIONAL_SHIFT;
> + entry >>= EVICTION_JIFFIES;
> + prev_jiff = (entry & ((1UL << EVICTION_JIFFIES) - 1)) << EVICTION_JIFFIES;
> nid = entry & ((1UL << NODES_SHIFT) - 1);
> entry >>= NODES_SHIFT;
> memcgid = entry & ((1UL << MEM_CGROUP_ID_SHIFT) - 1);
> @@ -195,6 +199,7 @@ static void unpack_shadow(void *shadow, int *memcgidp, pg_data_t **pgdat,
> *memcgidp = memcgid;
> *pgdat = NODE_DATA(nid);
> *evictionp = entry << bucket_order;
> + *prev_jiffp = prev_jiff;
> }
>
> /**
> @@ -242,8 +247,12 @@ bool workingset_refault(void *shadow)
> unsigned long refault;
> struct pglist_data *pgdat;
> int memcgid;
> + unsigned long refault_ratio;
> + unsigned long prev_jiff;
> + unsigned long avg_refault_time;
> + unsigned long refault_time;
>
> - unpack_shadow(shadow, &memcgid, &pgdat, &eviction);
> + unpack_shadow(shadow, &memcgid, &pgdat, &eviction, &prev_jiff);
>
> rcu_read_lock();
> /*
> @@ -288,10 +297,11 @@ bool workingset_refault(void *shadow)
> * list is not a problem.
> */
> refault_distance = (refault - eviction) & EVICTION_MASK;
> -
> inc_lruvec_state(lruvec, WORKINGSET_REFAULT);
> -
> - if (refault_distance <= active_file) {
> + lruvec->refaults_ratio = atomic_long_read(&lruvec->inactive_age) / jiffies;
I also wonder how many times the division above yields a 0...
> + refault_time = jiffies - prev_jiff;
> + avg_refault_time = refault_distance / lruvec->refaults_ratio;
and then used here as a denominator.
> + if (refault_time <= avg_refault_time) {
> inc_lruvec_state(lruvec, WORKINGSET_ACTIVATE);
> rcu_read_unlock();
> return true;
> @@ -521,7 +531,7 @@ static int __init workingset_init(void)
> * some more pages at runtime, so keep working with up to
> * double the initial memory by using totalram_pages as-is.
> */
> - timestamp_bits = BITS_PER_LONG - EVICTION_SHIFT;
> + timestamp_bits = BITS_PER_LONG - EVICTION_SHIFT - EVICTION_JIFFIES;
> max_order = fls_long(totalram_pages - 1);
> if (max_order > timestamp_bits)
> bucket_order = max_order - timestamp_bits;
> --
> 1.9.1
>