Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753695AbdIEXCm (ORCPT ); Tue, 5 Sep 2017 19:02:42 -0400 Received: from bombadil.infradead.org ([65.50.211.133]:36947 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752807AbdIEXCj (ORCPT ); Tue, 5 Sep 2017 19:02:39 -0400 Subject: Re: [PATCH 1/2] pidmap(2) To: Andrew Morton , Alexey Dobriyan Cc: Tatsiana Brouka , linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, Aliaksandr Patseyenak References: <20170905190500.GA13746@avx2> <20170905155320.a683a4853b21a3be32d8b529@linux-foundation.org> From: Randy Dunlap Message-ID: Date: Tue, 5 Sep 2017 16:02:37 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 MIME-Version: 1.0 In-Reply-To: <20170905155320.a683a4853b21a3be32d8b529@linux-foundation.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 908 Lines: 26 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