From: Aleksa Sarai <asarai@suse.de>
To: Tejun Heo <tj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>, Li Zefan <lizefan@huawei.com>,
Johannes Weiner <hannes@cmpxchg.org>, Kenny Yu <kennyyu@fb.com>,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
cgroups@vger.kernel.org
Subject: Re: [PATCH 1/2] cgroup: pids: show number of failed forks since limit reset
Date: Sun, 26 Jun 2016 21:34:41 +1000 [thread overview]
Message-ID: <78d17b23-d712-7d9c-3655-34c646bc4897@suse.de> (raw)
In-Reply-To: <20160624153151.GQ3262@mtj.duckdns.org>
> On Fri, Jun 24, 2016 at 01:00:48PM +1000, Aleksa Sarai wrote:
>> This allows users to dynamically adjust their limits based on how many
>> failed forks happened since they last reset their limits, otherwise they
>> would have to track (in a racy way) how many limit failures there were
>> since the last limit change manually. In addition, we log the first
>> failure since the limit was reset (which was the original semantics of
>> the patchset).
>
> Isn't that trivially achievable by reading the counter and then
> calculating the diff? I don't think it matters all that much whether
> the log message is printed once per cgroup or per config-change. It's
> just a hint for the admin to avoid setting her off on a wild goose
> chase.
If a user has a setup where they wait for notifications on changes to
pids.event, and then auto-adjust the cgroup limits based on the number
of failures you have a race condition between reading the pids.event
file and then setting the new limit. Then, upon getting notified again
there may have been many failed forks with the old limit set, so you
might decide to bump up the limit again.
It's not a huge deal, I just though it could be useful to alleviate
problems like the above.
--
Aleksa Sarai
Software Engineer (Containers)
SUSE Linux GmbH
https://www.cyphar.com/
next prev parent reply other threads:[~2016-06-26 11:30 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-24 3:00 [PATCH 0/2] cgroup: pids: extend pids.events Aleksa Sarai
2016-06-24 3:00 ` [PATCH 1/2] cgroup: pids: show number of failed forks since limit reset Aleksa Sarai
2016-06-24 3:00 ` [PATCH 2/2] docs: cgroup/pids: update documentation to include pids.events Aleksa Sarai
2016-06-24 15:31 ` [PATCH 1/2] cgroup: pids: show number of failed forks since limit reset Tejun Heo
2016-06-26 11:34 ` Aleksa Sarai [this message]
2016-06-26 23:42 ` Tejun Heo
2016-06-29 5:10 ` Aleksa Sarai
2016-06-29 15:33 ` Tejun Heo
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