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Date: Mon, 12 Oct 2009 14:58:10 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Neil Horman <nhorman@tuxdriver.com>
Cc: linux-kernel@vger.kernel.org, marcin.slusarz@gmail.com
Subject: Re: [PATCH 0/3] extend get/setrlimit to support setting rlimits
 external to a process (v5)
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On Mon, 12 Oct 2009 12:13:42 -0400
Neil Horman <nhorman@tuxdriver.com> wrote:

> Its been requested often that we have the ability to read and modify process
> rlimit values from contexts external to the owning process.  Ideally this allows
> sysadmins to adjust rlimits on long running processes wihout the need to stop
> and restart those processes, which incurs undesireable downtime.  This patch
> enables that functionality,  It does so in two places.  First it enables process
> limit setting by writing to the /proc/pid/limits file a string in the format:
> <limit> <current limit> <max limit> > /proc/<pid>/limits
> where limit is one of
> [as,core,cpu,data,fsize,locks,memlock,msgqueue,nice,nofile,nproc,rss,rtprio,rttime]
> 
> Secondly it allows for programatic setting of these limits via 2 new syscalls,
> getprlimit, and setprlimit, which act in an identical fashion to getrlimit and
> setrlimit respectively, except that they except a process id as an extra
> argument, to specify the process id of the rlimit values that you wish to
> read/write

I'm still not seeing why we need the /proc interface.

We've been using a syscall to set rlimits for ever and we've survived.

It just adds bloat and complexity to the kernel because putting a
100-line tool into util-linux is All Too Hard.

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