From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753861AbdEFHxA (ORCPT ); Sat, 6 May 2017 03:53:00 -0400 Received: from merlin.infradead.org ([205.233.59.134]:47802 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752011AbdEFHww (ORCPT ); Sat, 6 May 2017 03:52:52 -0400 Date: Sat, 6 May 2017 09:52:38 +0200 From: Peter Zijlstra To: Steven Rostedt Cc: LKML , Thomas Gleixner , Ingo Molnar , Clark Williams , Daniel Bristot de Oliveira , John Kacur , Scott Wood Subject: Re: [PATCH tip/sched/core v2] sched/rt: Simplify the IPI rt balancing logic Message-ID: <20170506075238.GD4626@worktop.programming.kicks-ass.net> References: <20170424114732.1aac6dc4@gandalf.local.home> <20170504153256.fbmglqe2zjo6ika2@hirez.programming.kicks-ass.net> <20170504132538.157f8ca7@gandalf.local.home> <20170504184200.3gjfciwqulgwpeln@hirez.programming.kicks-ass.net> <20170504150355.0524c8e8@gandalf.local.home> <20170505110529.bq4jflqvog2qmezc@hirez.programming.kicks-ass.net> <20170505080238.42b5bb20@gandalf.local.home> <20170505173949.yeyjwykbfwhckgi4@hirez.programming.kicks-ass.net> <20170505145916.1145edf6@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170505145916.1145edf6@gandalf.local.home> User-Agent: Mutt/1.5.22.1 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 05, 2017 at 02:59:16PM -0400, Steven Rostedt wrote: > On Fri, 5 May 2017 19:39:49 +0200 > Peter Zijlstra wrote: > > > On Fri, May 05, 2017 at 08:02:38AM -0400, Steven Rostedt wrote: > > > Actually what rteval does is basically 3 things. It runs cyclictest, > > > hackbench in a loop and a kernel build in a loop. > > > > Of those, only cyclictest uses RT tasks and would end up poking at the > > bits you just changed. > > > > So just running cyclictest should lock up a ~120 CPU machine? > > The other tools tend to trigger RT kernel threads as well, which causes > migration. cyclictest tasks don't migrate, but they do cause other > tasks to want to move around. There aren't that many RT threads on a !RT kernel. All my laptop has for example are: $ ps -faxo pid,class,comm | grep -v TS PID CLS COMMAND 9 FF \_ migration/0 10 FF \_ watchdog/0 11 FF \_ watchdog/1 12 FF \_ migration/1 16 FF \_ watchdog/2 17 FF \_ migration/2 21 FF \_ watchdog/3 22 FF \_ migration/3 714 FF \_ irq/48-iwlwifi 24254 FF \_ irq/47-mei_me 2444 B \_ baloo_file > You can try rt-migrate-test too, because I used that to trigger some > bugs in previous versions. Just running rt-migrate-test 'works' on the 144 CPU box. But I ran it while it was otherwise idle. That is, it ran in reasonable time and no lockup messages were produced. I can try and run it together with cyclictest, but over all this sounds like we're missing a usable test-case. If I have a spare moment (lol) I might poke at rt-migrate-test to see if I can make it more aggressive or something.