From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754859AbeBBUEf (ORCPT ); Fri, 2 Feb 2018 15:04:35 -0500 Received: from merlin.infradead.org ([205.233.59.134]:37206 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754717AbeBBUEF (ORCPT ); Fri, 2 Feb 2018 15:04:05 -0500 Date: Fri, 2 Feb 2018 21:04:01 +0100 From: Peter Zijlstra To: Steven Sistare Cc: subhra mazumdar , linux-kernel@vger.kernel.org, mingo@redhat.com, dhaval.giani@oracle.com Subject: Re: [RESEND RFC PATCH V3] sched: Improve scalability of select_idle_sibling using SMT balance Message-ID: <20180202200401.GS2269@hirez.programming.kicks-ass.net> References: <20180129233102.19018-1-subhra.mazumdar@oracle.com> <20180201123335.GV2249@hirez.programming.kicks-ass.net> <911d42cf-54c7-4776-c13e-7c11f8ebfd31@oracle.com> <20180202172153.GO2269@hirez.programming.kicks-ass.net> <5b9f0828-8d35-885b-3eba-d31ca46da642@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5b9f0828-8d35-885b-3eba-d31ca46da642@oracle.com> 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 Fri, Feb 02, 2018 at 01:34:58PM -0500, Steven Sistare wrote: > Actually, I take back my take back. I suspect the primary benefit > of random selection is that it breaks up resonance states where > CPUs that are busy tend to stay busy, and CPUs that are idle tend > to stay idle, which is reinforced by starting the search at target = > last cpu ran. Which, according to there here patches: https://lkml.kernel.org/r/20180130104555.4125-1-mgorman@techsingularity.net is a good thing, because of power management.