From: Chris Down <chris@chrisdown.name> To: David Rientjes <rientjes@google.com> Cc: Andrew Morton <akpm@linux-foundation.org>, Yang Shi <shy828301@gmail.com>, Michal Hocko <mhocko@kernel.org>, Shakeel Butt <shakeelb@google.com>, Yang Shi <yang.shi@linux.alibaba.com>, Roman Gushchin <guro@fb.com>, Greg Thelen <gthelen@google.com>, Johannes Weiner <hannes@cmpxchg.org>, Vladimir Davydov <vdavydov.dev@gmail.com>, cgroups@vger.kernel.org, linux-mm@kvack.org Subject: Re: [patch] mm, memcg: provide a stat to describe reclaimable memory Date: Wed, 15 Jul 2020 14:10:48 +0100 [thread overview] Message-ID: <20200715131048.GA176092@chrisdown.name> (raw) In-Reply-To: <alpine.DEB.2.23.453.2007142018150.2667860@chino.kir.corp.google.com> Hi David, I'm somewhat against adding more metrics which try to approximate availability of memory when we already know it not to generally manifest very well in practice, especially since this *is* calculable by userspace (albeit with some knowledge of mm internals). Users and applications often vastly overestimate the reliability of these metrics, especially since they heavily depend on transient page states and whatever reclaim efficacy happens to be achieved at the time there is demand. What do you intend to do with these metrics and how do you envisage other users should use them? Is it not possible to rework the strategy to use pressure information and/or workingset pressurisation instead? Thanks, Chris
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From: Chris Down <chris-6Bi1550iOqEnzZ6mRAm98g@public.gmane.org> 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 Subject: Re: [patch] mm, memcg: provide a stat to describe reclaimable memory Date: Wed, 15 Jul 2020 14:10:48 +0100 [thread overview] Message-ID: <20200715131048.GA176092@chrisdown.name> (raw) In-Reply-To: <alpine.DEB.2.23.453.2007142018150.2667860-X6Q0R45D7oAcqpCFd4KODRPsWskHk0ljAL8bYrjMMd8@public.gmane.org> Hi David, I'm somewhat against adding more metrics which try to approximate availability of memory when we already know it not to generally manifest very well in practice, especially since this *is* calculable by userspace (albeit with some knowledge of mm internals). Users and applications often vastly overestimate the reliability of these metrics, especially since they heavily depend on transient page states and whatever reclaim efficacy happens to be achieved at the time there is demand. What do you intend to do with these metrics and how do you envisage other users should use them? Is it not possible to rework the strategy to use pressure information and/or workingset pressurisation instead? Thanks, Chris
next prev parent reply other threads:[~2020-07-15 13:11 UTC|newest] Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-07-15 3:18 [patch] mm, memcg: provide a stat to describe reclaimable memory David Rientjes 2020-07-15 3:18 ` David Rientjes 2020-07-15 7:00 ` David Rientjes 2020-07-15 7:00 ` David Rientjes 2020-07-15 7:15 ` SeongJae Park 2020-07-15 7:15 ` SeongJae Park 2020-07-15 17:33 ` David Rientjes 2020-07-15 17:33 ` David Rientjes 2020-07-16 20:58 ` [patch] mm, memcg: provide an anon_reclaimable stat David Rientjes 2020-07-16 20:58 ` David Rientjes 2020-07-16 21:07 ` Shakeel Butt 2020-07-16 21:07 ` Shakeel Butt 2020-07-16 21:28 ` David Rientjes 2020-07-16 21:28 ` David Rientjes 2020-07-17 1:37 ` Shakeel Butt 2020-07-17 1:37 ` Shakeel Butt 2020-07-17 8:34 ` Michal Hocko 2020-07-17 8:34 ` Michal Hocko 2020-07-17 14:39 ` Johannes Weiner 2020-07-17 14:39 ` Johannes Weiner 2020-07-15 13:10 ` Chris Down [this message] 2020-07-15 13:10 ` [patch] mm, memcg: provide a stat to describe reclaimable memory Chris Down [not found] ` <20200715131048.GA176092-6Bi1550iOqEnzZ6mRAm98g@public.gmane.org> 2020-07-15 18:02 ` David Rientjes 2020-07-17 12:17 ` Chris Down 2020-07-17 12:17 ` Chris Down 2020-07-17 19:37 ` David Rientjes 2020-07-17 19:37 ` David Rientjes 2020-07-20 7:37 ` Michal Hocko 2020-07-20 7:37 ` Michal Hocko
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