linux-kernel - Re: [PATCH v4 2/6] mm: shrinkers: introduce debugfs interface for memory shrinkers

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Message-ID: <Yo7e0st/IiSpkfQR@FVFYT0MHHV2J.googleapis.com>
Date:   Thu, 26 May 2022 09:58:42 +0800
From:   Muchun Song <songmuchun@...edance.com>
To:     Roman Gushchin <roman.gushchin@...ux.dev>
Cc:     Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        Dave Chinner <dchinner@...hat.com>,
        linux-kernel@...r.kernel.org,
        Kent Overstreet <kent.overstreet@...il.com>,
        Hillf Danton <hdanton@...a.com>,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>
Subject: Re: [PATCH v4 2/6] mm: shrinkers: introduce debugfs interface for
 memory shrinkers

On Wed, May 25, 2022 at 01:25:56PM -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>
> Reviewed-by: Kent Overstreet <kent.overstreet@...il.com>

Acked-by: Muchun Song <songmuchun@...edance.com>

Thanks.