linux-kernel - Re: [PATCH v3 2/6] mm: shrinkers: introduce debugfs interface for memory shrinkers

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Message-ID: <Yogx8K98SQ+kyOlG@carbon>
Date:   Fri, 20 May 2022 17:27:28 -0700
From:   Roman Gushchin <roman.gushchin@...ux.dev>
To:     Kent Overstreet <kent.overstreet@...il.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        Dave Chinner <dchinner@...hat.com>,
        linux-kernel@...r.kernel.org, Hillf Danton <hdanton@...a.com>,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>
Subject: Re: [PATCH v3 2/6] mm: shrinkers: introduce debugfs interface for
 memory shrinkers

On Fri, May 20, 2022 at 12:45:12PM -0400, Kent Overstreet wrote:
> On Mon, May 09, 2022 at 11:38:16AM -0700, Roman Gushchin wrote:
> > This commit introduces the /sys/kernel/debug/shrinker debugfs
> > interface which provides an ability to observe the state of
> > individual kernel memory shrinkers.
> > 
> > Because the feature adds some memory overhead (which shouldn't be
> > large unless there is a huge amount of registered shrinkers), it's
> > guarded by a config option (enabled by default).
> > 
> > This commit introduces the "count" interface for each shrinker
> > registered in the system.
> > 
> > The output is in the following format:
> > <cgroup inode id> <nr of objects on node 0> <nr of objects on node 1>...
> > <cgroup inode id> <nr of objects on node 0> <nr of objects on node 1>...
> > ...
> > 
> > To reduce the size of output on machines with many thousands cgroups,
> > if the total number of objects on all nodes is 0, the line is omitted.
> > 
> > If the shrinker is not memcg-aware or CONFIG_MEMCG is off, 0 is
> > printed as cgroup inode id. If the shrinker is not numa-aware, 0's are
> > printed for all nodes except the first one.
> > 
> > This commit gives debugfs entries simple numeric names, which are not
> > very convenient. The following commit in the series will provide
> > shrinkers with more meaningful names.
> > 
> > Signed-off-by: Roman Gushchin <roman.gushchin@...ux.dev>
> 
> I think this looks reasonable
> 
> Reviewed-by: Kent Overstreet <kent.overstreet@...il.com>

Thank you!