linux-kernel - Re: [PATCH] mm: vmscan: consistent update to pgsteal and pgscan

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20200507222856.GB81857@carbon.dhcp.thefacebook.com>
Date:   Thu, 7 May 2020 15:28:56 -0700
From:   Roman Gushchin <guro@...com>
To:     Shakeel Butt <shakeelb@...gle.com>
CC:     Mel Gorman <mgorman@...e.de>, Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm: vmscan: consistent update to pgsteal and pgscan

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@...gle.com>

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

Thanks!