Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750887AbcCHRtP (ORCPT ); Tue, 8 Mar 2016 12:49:15 -0500 Received: from mail-wm0-f66.google.com ([74.125.82.66]:35071 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750817AbcCHRtA (ORCPT ); Tue, 8 Mar 2016 12:49:00 -0500 Date: Tue, 8 Mar 2016 18:48:56 +0100 From: Ingo Molnar To: Dmitry Vyukov Cc: Peter Zijlstra , Wang Nan , Ingo Molnar , LKML , He Kuang , Alexei Starovoitov , Arnaldo Carvalho de Melo , Brendan Gregg , Jiri Olsa , Masami Hiramatsu , Namhyung Kim , Zefan Li , pi3orama@163.com Subject: Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Message-ID: <20160308174856.GA28862@gmail.com> References: <20160308162703.GB30211@gmail.com> <20160308164438.GA24109@gmail.com> <20160308164859.GA27516@gmail.com> <20160308172425.GA3017@gmail.com> <20160308173709.GC3017@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2711 Lines: 58 * Dmitry Vyukov wrote: > On Tue, Mar 8, 2016 at 6:37 PM, Ingo Molnar wrote: > > > > * Dmitry Vyukov wrote: > > > >> > fomalhaut:~/go/src/github.com/google/syzkaller> ps aux | grep -i syz > >> > mingo 1374 0.0 0.0 118476 2376 pts/2 S+ 18:23 0:00 grep --color=auto -i syz > >> > > >> > and with no kernel messages in dmesg - and with a fully functional system. > >> > > >> > I'm running the 16-task load on a 120 CPU system - should I increase it to 120? > >> > Does the code expect to saturate the system? > >> > >> No, it does not expect to saturate the system. Set "procs" to 480, or > >> something like that. > > > > Does not seem to help much: > > > > fomalhaut:~> vmstat 10 > > procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu----- > > r b swpd free buff cache si so bi bo in cs us sy id wa st > > > > 1 0 0 257465904 219940 4736092 0 0 0 102 16022 4396 0 1 99 0 0 > > 2 0 0 257452144 220496 4755052 0 0 2 3649 14286 4627 0 1 99 0 0 > > 2 0 0 257473408 221188 4770824 0 0 15 1898 17175 4474 0 1 99 0 0 > > > > Only around 1% system utilization. Should I go for 1,000 or more? :) > > > > Peter, do you experience with running syz-kaller on larger CPU count Intel > > systems? > > > Try to set "dropprivs": false in config. Things got a lot more lively after that! But most of the overhead seems to come from systemd trying to dump core or something like that: 85872 mingo 20 0 34712 3016 2656 S 4.6 0.0 0:00.14 systemd-coredum 85440 mingo 20 0 34712 3028 2664 S 4.2 0.0 0:00.13 systemd-coredum 85751 mingo 20 0 34712 3076 2716 S 4.2 0.0 0:00.13 systemd-coredum 85840 mingo 20 0 34712 2988 2624 S 4.2 0.0 0:00.13 systemd-coredum 85861 mingo 20 0 34712 3080 2720 S 4.2 0.0 0:00.13 systemd-coredum 85954 mingo 20 0 34712 3028 2664 S 4.2 0.0 0:00.13 systemd-coredum and I have: fomalhaut:~/go/src/github.com/google/syzkaller> ulimit -c 0 weird ... Has any of you seen such behavior? Thanks, Ingo