From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1166248AbdEAJAl (ORCPT ); Mon, 1 May 2017 05:00:41 -0400 Received: from merlin.infradead.org ([205.233.59.134]:45714 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1166224AbdEAJAe (ORCPT ); Mon, 1 May 2017 05:00:34 -0400 Date: Mon, 1 May 2017 11:00:26 +0200 From: Peter Zijlstra To: Vincent Guittot Cc: mingo@kernel.org, linux-kernel@vger.kernel.org, dietmar.eggemann@arm.com, Morten.Rasmussen@arm.com, yuyang.du@intel.com, pjt@google.com, bsegall@google.com Subject: Re: [PATCH v2] sched/fair: update scale invariance of PELT Message-ID: <20170501090026.kht6tsttn6dirbrw@hirez.programming.kicks-ass.net> References: <1491815909-13345-1-git-send-email-vincent.guittot@linaro.org> <20170428220924.mxzs43zyvfqww2ze@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170428220924.mxzs43zyvfqww2ze@hirez.programming.kicks-ass.net> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Apr 29, 2017 at 12:09:24AM +0200, Peter Zijlstra wrote: > On Mon, Apr 10, 2017 at 11:18:29AM +0200, Vincent Guittot wrote: > > +++ b/include/linux/sched.h > > @@ -313,6 +313,7 @@ struct load_weight { > > */ > > struct sched_avg { > > u64 last_update_time; > > + u64 stolen_idle_time; > > u64 load_sum; > > u32 util_sum; > > u32 period_contrib; > > > + if (sa->util_sum < (LOAD_AVG_MAX * 1000)) { > > + /* > > + * Add the idle time stolen by running at lower compute > > + * capacity > > + */ > > + delta += sa->stolen_idle_time; > > + } > > + sa->stolen_idle_time = 0; > > > So I was wondering if stolen_idle_time really needs to be a u64. Afaict > we'll be at LOAD_AVG_MAX after LOAD_AVG_MAX_N periods, or LOAD_AVG_MAX_N > * LOAD_AVG_PERIOD time, which ends up being 11040. * 1024 or course, but still easily fits in u32.