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Message-ID: <CAJD7tkaVuiMU-ifJiyH5d_W1hi9DnAymYJxzBxEKCVX+tU=OCA@mail.gmail.com>
Date: Tue, 22 Aug 2023 09:00:06 -0700
From: Yosry Ahmed <yosryahmed@...gle.com>
To: Michal Koutný <mkoutny@...e.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Johannes Weiner <hannes@...xchg.org>,
Michal Hocko <mhocko@...nel.org>,
Roman Gushchin <roman.gushchin@...ux.dev>,
Shakeel Butt <shakeelb@...gle.com>,
Muchun Song <muchun.song@...ux.dev>,
Ivan Babrou <ivan@...udflare.com>, Tejun Heo <tj@...nel.org>,
linux-mm@...ck.org, cgroups@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] mm: memcg: add a helper for non-unified stats flushing
On Tue, Aug 22, 2023 at 6:01 AM Michal Koutný <mkoutny@...e.com> wrote:
>
> On Mon, Aug 21, 2023 at 08:54:57PM +0000, Yosry Ahmed <yosryahmed@...gle.com> wrote:
> > +static void do_stats_flush(struct mem_cgroup *memcg)
> > +{
> > + cgroup_rstat_flush(memcg->css.cgroup);
> if(memcg == root_mem_cgroup)
> atomic_set(&stats_flush_threshold, 0);
> > +}
> > +
> > /*
> > * do_unified_stats_flush - do a unified flush of memory cgroup statistics
> > *
> > @@ -656,7 +667,7 @@ static void do_unified_stats_flush(void)
> >
> > WRITE_ONCE(flush_next_time, jiffies_64 + 2*FLUSH_TIME);
> >
> > - cgroup_rstat_flush(root_mem_cgroup->css.cgroup);
> > + do_stats_flush(root_mem_cgroup);
> >
> - atomic_set(&stats_flush_threshold, 0);
> > atomic_set(&stats_flush_ongoing, 0);
>
> You may reset stats_flush_threshold to save the unified flushers some
> work.
We can probably also kick FLUSH_TIME forward as well. Perhaps I can
move both into do_stats_flush() then. If I understand correctly this
is what you mean?
static void do_stats_flush(struct mem_cgroup *memcg)
{
if (mem_cgroup_is_root(memcg))
WRITE_ONCE(flush_next_time, jiffies_64 + 2*FLUSH_TIME);
cgroup_rstat_flush(memcg->css.cgroup);
if (mem_cgroup_is_root(memcg))
atomic_set(&stats_flush_threshold, 0);
}
static void do_unified_stats_flush(void)
{
if (atomic_read(&stats_flush_ongoing) ||
atomic_xchg(&stats_flush_ongoing, 1))
return;
do_stats_flush(root_mem_cgroup);
atomic_set(&stats_flush_ongoing, 0);
}
, or simplify it further by just resetting stats_flush_threshold
before we flush as well:
static void do_stats_flush(struct mem_cgroup *memcg)
{
/* for unified flushing, root non-unified flushing can help as well */
if (mem_cgroup_is_root(memcg)) {
WRITE_ONCE(flush_next_time, jiffies_64 + 2*FLUSH_TIME);
atomic_set(&stats_flush_threshold, 0);
}
cgroup_rstat_flush(memcg->css.cgroup);
}
static void do_unified_stats_flush(void)
{
if (atomic_read(&stats_flush_ongoing) ||
atomic_xchg(&stats_flush_ongoing, 1))
return;
do_stats_flush(root_mem_cgroup);
atomic_set(&stats_flush_ongoing, 0);
}
What do you think?
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