From mboxrd@z Thu Jan  1 00:00:00 1970
From: SeongJae Park <sjpark-vV1OtcyAfmbQT0dZR+AlfA@public.gmane.org>
Subject: Re: Re: [patch] mm, memcg: provide a stat to describe reclaimable memory
Date: Wed, 15 Jul 2020 09:15:22 +0200
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To: David Rientjes <rientjes-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
Cc: Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>, Yang Shi <shy828301-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Michal Hocko <mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Shakeel Butt <shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, Yang Shi <yang.shi-KPsoFbNs7GizrGE5bRqYAgC/G2K4zDHf@public.gmane.org>, Roman Gushchin <guro-b10kYP2dOMg@public.gmane.org>, Greg Thelen <gthelen-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>, Vladimir Davydov <vdavydov.dev-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org

Hello David,

On Wed, 15 Jul 2020 00:00:03 -0700 (PDT) David Rientjes <rientjes-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org> wrote:

> On Tue, 14 Jul 2020, David Rientjes wrote:
> 
[...]
> 
> An alternative to this would also be to change from an "available" metric 
> to an "anon_reclaimable" metric since both the deferred split queues and 
> lazy freeable memory would pertain to anon.  This would no longer attempt 
> to mimic MemAvailable and leave any such calculation to userspace
> (anon_reclaimable + (file + slab_reclaimable) / 2).
> 
> With this route, care would need to be taken to clearly indicate that 
> anon_reclaimable is not necessarily a subset of the "anon" metric since 
> reclaimable memory from compound pages on deferred split queues is not 
> mapped, so it doesn't show up in NR_ANON_MAPPED.
> 
> I'm indifferent to either approach and would be happy to switch to 
> anon_reclaimable if others agree and doesn't foresee any extensibility 
> issues.

Agreed, I was also once confused about the 'MemAvailable'.  The 'reclaimable'
might be better to understand.


Thanks,
SeongJae Park