The patch titled
Subject: memcg: unify memcg stat flushing
has been added to the -mm tree. Its filename is
memcg-unify-memcg-stat-flushing.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/memcg-unify-memcg-stat-flushing.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/memcg-unify-memcg-stat-flushing.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Shakeel Butt <shakeelb@xxxxxxxxxx>
Subject: memcg: unify memcg stat flushing
The memcg stats can be flushed in multiple context and potentially in
parallel too. For example multiple parallel user space readers for memcg
stats will contend on the rstat locks with each other. There is no need
for that. We just need one flusher and everyone else can benefit. In
addition after aa48e47e3906 ("memcg: infrastructure to flush memcg stats")
the kernel periodically flush the memcg stats from the root, so, the other
flushers will potentially have much less work to do.
Link: https://lkml.kernel.org/r/20210930044711.2892660-2-shakeelb@xxxxxxxxxx
Signed-off-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: "Michal Koutný" <mkoutny@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 19 ++++++++++---------
1 file changed, 10 insertions(+), 9 deletions(-)
--- a/mm/memcontrol.c~memcg-unify-memcg-stat-flushing
+++ a/mm/memcontrol.c
@@ -1425,7 +1425,7 @@ static char *memory_stat_format(struct m
*
* Current memory state:
*/
- cgroup_rstat_flush(memcg->css.cgroup);
+ mem_cgroup_flush_stats();
for (i = 0; i < ARRAY_SIZE(memory_stats); i++) {
u64 size;
@@ -3529,8 +3529,7 @@ static unsigned long mem_cgroup_usage(st
unsigned long val;
if (mem_cgroup_is_root(memcg)) {
- /* mem_cgroup_threshold() calls here from irqsafe context */
- cgroup_rstat_flush_irqsafe(memcg->css.cgroup);
+ mem_cgroup_flush_stats();
val = memcg_page_state(memcg, NR_FILE_PAGES) +
memcg_page_state(memcg, NR_ANON_MAPPED);
if (swap)
@@ -3911,7 +3910,7 @@ static int memcg_numa_stat_show(struct s
int nid;
struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
- cgroup_rstat_flush(memcg->css.cgroup);
+ mem_cgroup_flush_stats();
for (stat = stats; stat < stats + ARRAY_SIZE(stats); stat++) {
seq_printf(m, "%s=%lu", stat->name,
@@ -3983,7 +3982,7 @@ static int memcg_stat_show(struct seq_fi
BUILD_BUG_ON(ARRAY_SIZE(memcg1_stat_names) != ARRAY_SIZE(memcg1_stats));
- cgroup_rstat_flush(memcg->css.cgroup);
+ mem_cgroup_flush_stats();
for (i = 0; i < ARRAY_SIZE(memcg1_stats); i++) {
unsigned long nr;
@@ -4486,7 +4485,7 @@ void mem_cgroup_wb_stats(struct bdi_writ
struct mem_cgroup *memcg = mem_cgroup_from_css(wb->memcg_css);
struct mem_cgroup *parent;
- cgroup_rstat_flush_irqsafe(memcg->css.cgroup);
+ mem_cgroup_flush_stats();
*pdirty = memcg_page_state(memcg, NR_FILE_DIRTY);
*pwriteback = memcg_page_state(memcg, NR_WRITEBACK);
@@ -5354,12 +5353,14 @@ static void mem_cgroup_css_reset(struct
static void __mem_cgroup_flush_stats(void)
{
- if (!spin_trylock(&stats_flush_lock))
+ unsigned long flag;
+
+ if (!spin_trylock_irqsave(&stats_flush_lock, flag))
return;
cgroup_rstat_flush_irqsafe(root_mem_cgroup->css.cgroup);
atomic_set(&stats_flush_threshold, 0);
- spin_unlock(&stats_flush_lock);
+ spin_unlock_irqrestore(&stats_flush_lock, flag);
}
void mem_cgroup_flush_stats(void)
@@ -6391,7 +6392,7 @@ static int memory_numa_stat_show(struct
int i;
struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
- cgroup_rstat_flush(memcg->css.cgroup);
+ mem_cgroup_flush_stats();
for (i = 0; i < ARRAY_SIZE(memory_stats); i++) {
int nid;
_
Patches currently in -mm which might be from shakeelb@xxxxxxxxxx are
memcg-flush-stats-only-if-updated.patch
memcg-unify-memcg-stat-flushing.patch
