From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752062AbbINRgi (ORCPT ); Mon, 14 Sep 2015 13:36:38 -0400 Received: from mail-pa0-f42.google.com ([209.85.220.42]:36789 "EHLO mail-pa0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751307AbbINRgh (ORCPT ); Mon, 14 Sep 2015 13:36:37 -0400 From: bsegall@google.com To: Yuyang Du Cc: Morten Rasmussen , Peter Zijlstra , Dietmar Eggemann , Vincent Guittot , Steve Muckle , "mingo\@redhat.com" , "daniel.lezcano\@linaro.org" , "mturquette\@baylibre.com" , "rjw\@rjwysocki.net" , Juri Lelli , "sgurrappadi\@nvidia.com" , "pang.xunlei\@zte.com.cn" , "linux-kernel\@vger.kernel.org" Subject: Re: [PATCH 5/6] sched/fair: Get rid of scaling utilization by capacity_orig References: <55EDAF43.30500@arm.com> <55EDDD5A.70904@arm.com> <55EED99E.2040100@arm.com> <20150909201519.GB21833@intel.com> <20150910100727.GU3644@twins.programming.kicks-ass.net> <20150911002825.GA3014@intel.com> <20150911103059.GH27098@e105550-lin.cambridge.arm.com> <20150911182451.GA11102@intel.com> Date: Mon, 14 Sep 2015 10:36:34 -0700 In-Reply-To: <20150911182451.GA11102@intel.com> (Yuyang Du's message of "Sat, 12 Sep 2015 02:24:51 +0800") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Yuyang Du writes: > On Fri, Sep 11, 2015 at 10:05:53AM -0700, bsegall@google.com wrote: >> >> SCHED_LOAD_RESOLUTION and the non-SLR part of SCHED_LOAD_SHIFT are not >> required to be the same value and should not be conflated. > >> In particular, since cgroups are on the same timeline as tasks and their >> shares are not scaled by SCHED_LOAD_SHIFT in any way (but are scaled so >> that SCHED_LOAD_RESOLUTION is invisible), changing that part of >> SCHED_LOAD_SHIFT would cause issues, since things can assume that nice-0 >> = 1024. However changing SCHED_LOAD_RESOLUTION would be fine, as that is >> an internal value to the kernel. >> >> In addition, changing the non-SLR part of SCHED_LOAD_SHIFT would require >> recomputing all of prio_to_weight/wmult for the new NICE_0_LOAD. > > Not fully looked into the concerns, but the new SCHED_RESOLUTION_SHIFT > is intended to formalize all the integer metrics that need better resolution. > It is not special to any metric, so actually it is to de-conflate whoever is > conflated. It conflates the userspace-invisible SCHED_LOAD_RESOLUTION with the userspace-visible value of scale_load_down(NICE_0_LOAD). Increasing SCHED_LOAD_RESOLUTION must not change scale_load_down(NICE_0_LOAD).