From: brookxu <brookxu.cn@gmail.com>
To: Tejun Heo <tj@kernel.org>
Cc: viro@zeniv.linux.org.uk, lizefan.x@bytedance.com,
hannes@cmpxchg.org, linux-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org, cgroups@vger.kernel.org
Subject: Re: [RFC PATCH v2 1/3] misc_cgroup: add support for nofile limit
Date: Wed, 28 Jul 2021 11:17:08 +0800 [thread overview]
Message-ID: <ca2bdc60-f117-e917-85b1-8c9ec0c6942f@gmail.com> (raw)
In-Reply-To: <YQA1D1GRiF9+px/s@mtj.duckdns.org>
Tejun Heo wrote on 2021/7/28 12:32 上午:
> Hello,
>
> On Tue, Jul 27, 2021 at 11:18:00AM +0800, brookxu wrote:
>> According to files_maxfiles_init(), we only allow about 10% of free memory to
>> create filps, and each filp occupies about 1K of cache. In this way, on a 16G
>> memory machine, the maximum usable filp is about 1,604,644. In general
>> scenarios, this may not be a big problem, but if the task is abnormal, it will
>> very likely become a bottleneck and affect other modules.
>
> Yeah but that can be configured trivially through sysfs. The reason why the
> default limit is lowered is because we wanna prevent a part of system to
> consume all the memory through fds. With cgroups, we already have that
> protection and at least some systems already configure file-max to maximum,
> so I don't see a point in adding another interface to subdivide the
> artificial limit.
>
Yeah we can adjust file-max through sysctl, but in many cases we adjust it according
to the actual load of the machine, not for abnormal tasks. Another problem is that in
practical applications, kmem_limit will cause some minor problems. In many cases,
kmem_limit is disabled. Limit_in_bytes mainly counts user pages and pagecache, which
may cause files_cache to be out of control. In this case, if file-max is set to MAX,
we may have a risk in the abnormal scene, which prevents us from recovering from the
abnormal scene. Maybe I missed something.
> Thanks.
>
next prev parent reply other threads:[~2021-07-28 3:17 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-22 15:20 [RFC PATCH v2 1/3] misc_cgroup: add support for nofile limit brookxu
2021-07-22 15:20 ` [RFC PATCH v2 2/3] misc_cgroup: add failcnt counter brookxu
2021-07-22 15:20 ` [RFC PATCH v2 3/3] misc_cgroup: delete failed logs to avoid log flooding brookxu
2021-07-26 21:27 ` [RFC PATCH v2 1/3] misc_cgroup: add support for nofile limit Tejun Heo
2021-07-27 3:18 ` brookxu
2021-07-27 16:32 ` Tejun Heo
2021-07-28 3:17 ` brookxu [this message]
2021-07-28 7:41 ` Tejun Heo
2021-07-28 9:47 ` brookxu
2021-07-28 15:38 ` Tejun Heo
2021-07-29 6:37 ` brookxu
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