From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754701AbdEDRjL (ORCPT ); Thu, 4 May 2017 13:39:11 -0400 Received: from mail-yb0-f194.google.com ([209.85.213.194]:36652 "EHLO mail-yb0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751474AbdEDRjE (ORCPT ); Thu, 4 May 2017 13:39:04 -0400 Date: Thu, 4 May 2017 13:39:01 -0400 From: Tejun Heo To: Dietmar Eggemann Cc: Peter Zijlstra , Ingo Molnar , linux-kernel@vger.kernel.org, Linus Torvalds , Vincent Guittot , Mike Galbraith , Paul Turner , Chris Mason , kernel-team@fb.com Subject: Re: [PATCH v2 1/2] sched/fair: Fix how load gets propagated from cfs_rq to its sched_entity Message-ID: <20170504173901.GB7288@htj.duckdns.org> References: <20170424201344.GA14169@wtj.duckdns.org> <20170424201415.GB14169@wtj.duckdns.org> <20170424213324.GA23619@wtj.duckdns.org> <20170503180028.ejf73et3pc4meqji@hirez.programming.kicks-ass.net> <20170503214546.GA7451@htj.duckdns.org> <20170504055129.c7f7whdqpcqyvnrz@hirez.programming.kicks-ass.net> <20170504062109.d5o2dz6t4lqnkp5n@hirez.programming.kicks-ass.net> <02c93bb0-ad3c-9a01-0351-e4ee6e56bf1b@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <02c93bb0-ad3c-9a01-0351-e4ee6e56bf1b@arm.com> User-Agent: Mutt/1.8.0 (2017-02-23) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, Dietmar. On Thu, May 04, 2017 at 10:49:51AM +0100, Dietmar Eggemann wrote: > On 04/05/17 07:21, Peter Zijlstra wrote: > > On Thu, May 04, 2017 at 07:51:29AM +0200, Peter Zijlstra wrote: > > > >> Urgh, and my numbers were so pretty :/ > > > > Just to clarify on how to run schbench, I limited to a single socket (as > > that is what you have) and set -t to the number of cores in the socket > > (not the number of threads). > > > > Furthermore, my machine is _idle_, if I don't do anything, it doesn't do > > _anything_. > > > > I can't recreate this problem running 'numactl -N 0 ./schbench -m 2 -t > 10 -s 10000 -c 15000 -r 30' on my E5-2690 v2 (IVB-EP, 2 sockets, 10 > cores / socket, 2 threads / core) > > I tried tip/sched/core comparing running in 'cpu:/' and 'cpu:/foo' and > > using your patch on top with all the combinations of {NO_}FUDGE, > {NO_}FUDGE2 with prop_type=shares_avg or prop_type_runnable. > > Where you able to see the issue on tip/sched/core w/o your patch on your > machine? > > The workload of n 60% periodic tasks on n logical cpus always creates a > very stable task distribution for me. It depends heavily on what else is going on in the system. On the test systems that I'm using, there's always something not-too-heavy going on. The pattern over time isn't too varied and the latency results are usually stable and the grouping of results is very clear as the difference between the load balancer working properly and not shows up as upto an order of magnitude difference in p99 latencies. For these differences to matter, you need to push the machine so that it's right at the point of saturation - e.g. increase duty cycle till p99 starts to deteriorate w/o cgroup. Thanks. -- tejun