linux-kernel - Re: [PATCH] proc/sysctl: prune stale dentries during unregistering

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Message-ID: <26fa33ed-365e-f4c9-9270-421420c16163@yandex-team.ru>
Date:   Fri, 10 Feb 2017 10:54:07 +0300
From:   Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
To:     Al Viro <viro@...IV.linux.org.uk>
Cc:     linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>
Subject: Re: [PATCH] proc/sysctl: prune stale dentries during unregistering

On 10.02.2017 10:47, Al Viro wrote:
> On Fri, Feb 10, 2017 at 10:35:02AM +0300, Konstantin Khlebnikov wrote:
>
>> # time sysctl -a > /dev/null
>> real    1m12.806s
>> user    0m0.016s
>> sys     1m12.400s
>>
>> Currently only memory reclaimer could remove this garbage.
>> But without significant memory pressure this never happens.
>>
>> This patch collects sysctl inodes into list on sysctl table header and
>> prunes all their dentries once that table unregisters.
>
> I'd probably go for hlist, but that's mostly cosmetic difference; how about
> the matching stats *after* that patch?
>

dcache size doesn't grow endlessly, so stats are fine

# sysctl fs.dentry-state
fs.dentry-state = 92712	58376	45	0	0	0

# time sysctl -a &>/dev/null

real	0m0.013s
user	0m0.004s
sys	0m0.008s