From mboxrd@z Thu Jan 1 00:00:00 1970 From: Randy Dunlap Subject: Re: [PATCH 1/2] pidmap(2) Date: Tue, 5 Sep 2017 16:02:37 -0700 Message-ID: References: <20170905190500.GA13746@avx2> <20170905155320.a683a4853b21a3be32d8b529@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20170905155320.a683a4853b21a3be32d8b529-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org> Content-Language: en-US Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Andrew Morton , Alexey Dobriyan Cc: Tatsiana Brouka , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Aliaksandr Patseyenak List-Id: linux-api@vger.kernel.org On 09/05/17 15:53, Andrew Morton wrote: > On Tue, 5 Sep 2017 22:05:00 +0300 Alexey Dobriyan wrote: > >> Implement system call for bulk retrieveing of pids in binary form. >> >> Using /proc is slower than necessary: 3 syscalls + another 3 for each thread + >> converting with atoi(). >> >> /proc may be not mounted especially in containers. Natural extension of >> hidepid=2 efforts is to not mount /proc at all. >> >> It could be used by programs like ps, top or CRIU. Speed increase will >> become more drastic once combined with bulk retrieval of process statistics. > > The patches are performance optimizations, but their changelogs contain > no performance measurements! > > Demonstration of some compelling real-world performance benefits would > help things along a lot. > also, I expect that the tiny kernel people will want kconfig options for these syscalls. -- ~Randy