From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752438AbaJCGEa (ORCPT ); Fri, 3 Oct 2014 02:04:30 -0400 Received: from mail-lb0-f180.google.com ([209.85.217.180]:38455 "EHLO mail-lb0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751189AbaJCGE2 (ORCPT ); Fri, 3 Oct 2014 02:04:28 -0400 Message-ID: <1412316263.5149.9.camel@marge.simpson.net> Subject: Re: [PATCH RFC] sched,idle: teach select_idle_sibling about idle states From: Mike Galbraith To: Rik van Riel Cc: Nicolas Pitre , Peter Zijlstra , Ingo Molnar , Daniel Lezcano , "Rafael J. Wysocki" , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, linaro-kernel@lists.linaro.org Date: Fri, 03 Oct 2014 08:04:23 +0200 In-Reply-To: <20141002131548.6cd377d5@cuia.bos.redhat.com> References: <1409844730-12273-1-git-send-email-nicolas.pitre@linaro.org> <1409844730-12273-3-git-send-email-nicolas.pitre@linaro.org> <542B277D.7050103@redhat.com> <20141002131548.6cd377d5@cuia.bos.redhat.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2014-10-02 at 13:15 -0400, Rik van Riel wrote: > This patch is ugly. I have not bothered cleaning it up, because it > causes a regression with hackbench. Apparently for hackbench (and > potentially other sync wakeups), locality is more important than > idleness. > > We may need to add a third clause before the search, something > along the lines of, to ensure target gets selected if neither > target or i are idle and the wakeup is synchronous... > > if (sync_wakeup && cpu_of(target)->nr_running == 1) > return target; I recommend you forget that trusting sync hint ever sprang to mind, it is often a big fat lie. -Mike