From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Gleixner Subject: Re: [PATCH 1/2] pidmap(2) Date: Wed, 6 Sep 2017 10:30:04 +0200 (CEST) Message-ID: References: <20170905190500.GA13746@avx2> <20170905155320.a683a4853b21a3be32d8b529@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Return-path: In-Reply-To: Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Randy Dunlap Cc: Andrew Morton , Alexey Dobriyan , Tatsiana Brouka , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Aliaksandr Patseyenak List-Id: linux-api@vger.kernel.org On Tue, 5 Sep 2017, Randy Dunlap wrote: > 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. And of course that stuff wants the corresponding man pages written up. Thanks, tglx