From mboxrd@z Thu Jan  1 00:00:00 1970
From: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Subject: Re: [RFC PATCH v2 1/3] misc_cgroup: add support for nofile limit
Date: Tue, 27 Jul 2021 06:32:15 -1000
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To: brookxu <brookxu.cn-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org, lizefan.x-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org, hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org

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.

Thanks.

-- 
tejun