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From: Roman Gushchin <guro@fb.com>
To: Shakeel Butt <shakeelb@google.com>
Cc: Mel Gorman <mgorman@suse.de>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Michal Hocko <mhocko@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>, <linux-mm@kvack.org>,
	<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mm: vmscan: consistent update to pgsteal and pgscan
Date: Thu, 7 May 2020 15:28:56 -0700	[thread overview]
Message-ID: <20200507222856.GB81857@carbon.dhcp.thefacebook.com> (raw)
In-Reply-To: <20200507204913.18661-1-shakeelb@google.com>

On Thu, May 07, 2020 at 01:49:13PM -0700, Shakeel Butt wrote:
> One way to measure the efficiency of memory reclaim is to look at the
> ratio (pgscan+pfrefill)/pgsteal. However at the moment these stats are
> not updated consistently at the system level and the ratio of these are
> not very meaningful. The pgsteal and pgscan are updated for only global
> reclaim while pgrefill gets updated for global as well as cgroup
> reclaim.
> 
> Please note that this difference is only for system level vmstats. The
> cgroup stats returned by memory.stat are actually consistent. The
> cgroup's pgsteal contains number of reclaimed pages for global as well
> as cgroup reclaim. So, one way to get the system level stats is to get
> these stats from root's memory.stat but root does not expose that
> interface. Also for !CONFIG_MEMCG machines /proc/vmstat is the only way
> to get these stats. So, make these stats consistent.
> 
> Signed-off-by: Shakeel Butt <shakeelb@google.com>

Acked-by: Roman Gushchin <guro@fb.com>

Thanks!

  reply	other threads:[~2020-05-07 22:29 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-07 20:49 [PATCH] mm: vmscan: consistent update to pgsteal and pgscan Shakeel Butt
2020-05-07 20:49 ` Shakeel Butt
2020-05-07 22:28 ` Roman Gushchin [this message]
2020-05-08 10:34 ` Yafang Shao
2020-05-08 10:34   ` Yafang Shao
2020-05-08 13:25   ` Shakeel Butt
2020-05-08 13:25     ` Shakeel Butt
2020-05-08 13:38     ` Johannes Weiner
2020-05-08 14:05       ` Shakeel Butt
2020-05-08 14:05         ` Shakeel Butt
2020-05-09  6:53       ` Yafang Shao
2020-05-09  6:53         ` Yafang Shao

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