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From:   Shakeel Butt <shakeelb@google.com>
Date:   Thu, 24 Jun 2021 08:00:31 -0700
Message-ID: <CALvZod4zaJZ1VjSQNvV7oUDZ58VYWvEUBa5WsGU4SYWnT70vbw@mail.gmail.com>
Subject: Re: [PATCH v2 2/2] memcg: periodically flush the memcg stats
To:     =?UTF-8?Q?Michal_Koutn=C3=BD?= <mkoutny@suse.com>
Cc:     Tejun Heo <tj@kernel.org>, Johannes Weiner <hannes@cmpxchg.org>,
        Muchun Song <songmuchun@bytedance.com>,
        Michal Hocko <mhocko@kernel.org>, Roman Gushchin <guro@fb.com>,
        Huang Ying <ying.huang@intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Cgroups <cgroups@vger.kernel.org>, Linux MM <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>
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On Thu, Jun 24, 2021 at 7:01 AM Michal Koutn=C3=BD <mkoutny@suse.com> wrote=
:
>
> Hello Shakeel.
>
> On Tue, Jun 15, 2021 at 10:44:35AM -0700, Shakeel Butt <shakeelb@google.c=
om> wrote:
> > At the moment memcg stats are read in four contexts:
> >
> > 1. memcg stat user interfaces
> > 2. dirty throttling
> > 3. page fault
> > 4. memory reclaim
>
> Sorry for being dense or ignorant -- what do you refer to with the point
> no. 3 (memcg stats reader during page fault)?
>

Yes, specifically workingset_refault() which reads lruvec stats
directly through lruvec_page_state and indirectly through
lru_note_cost_page.