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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 aa48e47e39 ("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/20211001190040.48086-2-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: "Michal Koutný" <mkoutny@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Shakeel Butt 2021-11-05 13:37:34 -07:00 committed by Linus Torvalds
parent 11192d9c12
commit fd25a9e0e2
1 changed files with 10 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
mm/memcontrol.c
View File

@ -660,12 +660,14 @@ static inline void memcg_rstat_updated(struct mem_cgroup *memcg)
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)
@ -1461,7 +1463,7 @@ static char *memory_stat_format(struct mem_cgroup *memcg)
*
* Current memory state:
*/
cgroup_rstat_flush(memcg->css.cgroup);
mem_cgroup_flush_stats();
for (i = 0; i < ARRAY_SIZE(memory_stats); i++) {
u64 size;
@ -3565,8 +3567,7 @@ static unsigned long mem_cgroup_usage(struct mem_cgroup *memcg, bool swap)
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)
@ -3947,7 +3948,7 @@ static int memcg_numa_stat_show(struct seq_file *m, void *v)
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,
@ -4019,7 +4020,7 @@ static int memcg_stat_show(struct seq_file *m, void *v)
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;
@ -4522,7 +4523,7 @@ void mem_cgroup_wb_stats(struct bdi_writeback *wb, unsigned long *pfilepages,
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);
@ -6405,7 +6406,7 @@ static int memory_numa_stat_show(struct seq_file *m, void *v)
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;