From: Tejun Heo <tj@kernel.org>
To: Michal Hocko <mhocko@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
vdavydov.dev@gmail.com, guro@fb.com, riel@surriel.com,
akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
kernel-team@fb.com, cgroups@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 1/3] mm: memcontrol: Use cgroup_rstat for event accounting
Date: Wed, 4 Apr 2018 09:58:29 -0700 [thread overview]
Message-ID: <20180404165829.GA3126663@devbig577.frc2.facebook.com> (raw)
In-Reply-To: <20180404143447.GJ6312@dhcp22.suse.cz>
Hello,
On Wed, Apr 04, 2018 at 04:34:47PM +0200, Michal Hocko wrote:
> > > The lazy updates are neat, but I'm a little concerned at the memory
> > > footprint. On a 64-cpu machine for example, this adds close to 9000
> > > words to struct mem_cgroup. And we really only need the accuracy for
> > > the 4 cgroup items in memory.events, not all VM events and stats.
> > >
> > > Why not restrict the patch to those? It would also get rid of the
> > > weird sharing between VM and cgroup enums.
> >
> > In fact, I wonder if we need per-cpuness for MEMCG_LOW, MEMCG_HIGH
> > etc. in the first place. They describe super high-level reclaim and
> > OOM events, so they're not nearly as hot as other VM events and
> > stats. We could probably just have a per-memcg array of atomics.
>
> Agreed!
Ah, yeah, if we aren't worried about the update frequency of
MEMCG_HIGH, which likely is the highest freq, we can just switch to
atomic_t. I'm gonna apply the cgroup stat refactoring patches to
cgroup, so if we ever wanna switch the counter to rstat, we can easily
do that later.
Thasnks.
--
tejun
next prev parent reply other threads:[~2018-04-04 16:58 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-24 16:08 [PATCHSET] mm, memcontrol: Make cgroup_rstat available to controllers Tejun Heo
2018-03-24 16:08 ` [PATCH 1/3] mm: memcontrol: Use cgroup_rstat for event accounting Tejun Heo
2018-04-04 14:08 ` Johannes Weiner
2018-04-04 14:18 ` Johannes Weiner
2018-04-04 14:34 ` Michal Hocko
2018-04-04 16:58 ` Tejun Heo [this message]
2018-04-05 17:55 ` [PATCH] mm: memcg: make sure memory.events is uptodate when waking pollers Johannes Weiner
2018-04-05 19:45 ` Tejun Heo
2018-04-06 12:03 ` Michal Hocko
2018-03-24 16:09 ` [PATCH 2/3] mm: memcontrol: Use cgroup_rstat for stat accounting Tejun Heo
2018-03-24 16:09 ` [PATCH 3/3] mm: memcontrol: Remove lruvec_stat Tejun Heo
2018-04-04 14:13 ` Johannes Weiner
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