From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752226AbeBTNFU (ORCPT ); Tue, 20 Feb 2018 08:05:20 -0500 Received: from merlin.infradead.org ([205.233.59.134]:55426 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751936AbeBTNCB (ORCPT ); Tue, 20 Feb 2018 08:02:01 -0500 Date: Mon, 19 Feb 2018 15:53:35 +0100 From: Peter Zijlstra To: Morten Rasmussen Cc: mingo@redhat.com, valentin.schneider@arm.com, dietmar.eggemann@arm.com, vincent.guittot@linaro.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 4/7] sched/fair: Avoid unnecessary balancing of asymmetric capacity groups Message-ID: <20180219145335.GN25235@hirez.programming.kicks-ass.net> References: <1518711654-23503-1-git-send-email-morten.rasmussen@arm.com> <1518711654-23503-5-git-send-email-morten.rasmussen@arm.com> <20180219145012.GH25181@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180219145012.GH25181@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 19, 2018 at 03:50:12PM +0100, Peter Zijlstra wrote: > On Thu, Feb 15, 2018 at 04:20:51PM +0000, Morten Rasmussen wrote: > > On systems with asymmetric cpu capacities, a skewed load distribution > > might yield better throughput than balancing load per group capacity. > > For example, preferring high capacity cpus for compute intensive tasks > > leaving low capacity cpus idle rather than balancing the number of idle > > cpus across different cpu types. Instead, let load-balance back off if > > the busiest group isn't really overloaded. > > I'm sorry. I just can't seem to make sense of that today. What? Aah, you're saying that is we have 4+4 bit.little and 4 runnable tasks, we would like them running on our big cluster and leave the small cluster entirely idle, instead of runnint 2+2. So what about this DynamicQ nonsense? Or is that so unstructured we can't really do anything sensible with it?