Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756863Ab2HULFI (ORCPT ); Tue, 21 Aug 2012 07:05:08 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:55350 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754501Ab2HULFF (ORCPT ); Tue, 21 Aug 2012 07:05:05 -0400 MIME-Version: 1.0 In-Reply-To: <5032DD22.4000909@intel.com> References: <5028F12C.7080405@intel.com> <1345028738.31459.82.camel@twins> <5032DD22.4000909@intel.com> Date: Tue, 21 Aug 2012 13:05:04 +0200 Message-ID: Subject: Re: [discussion]sched: a rough proposal to enable power saving in scheduler From: Vincent Guittot To: Alex Shi Cc: Peter Zijlstra , Suresh Siddha , Arjan van de Ven , svaidy@linux.vnet.ibm.com, Ingo Molnar , Andrew Morton , Linus Torvalds , "linux-kernel@vger.kernel.org" , Thomas Gleixner , Paul Turner Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2186 Lines: 58 On 21 August 2012 02:58, Alex Shi wrote: > On 08/20/2012 11:36 PM, Vincent Guittot wrote: > >>> > What you want it to keep track of a per-cpu utilization level (inverse >>> > of idle-time) and using PJTs per-task runnable avg see if placing the >>> > new task on will exceed the utilization limit. >>> > >>> > I think some of the Linaro people actually played around with this, >>> > Vincent? >> Sorry for the late reply but I had almost no network access during last weeks. >> >> So Linaro also works on a power aware scheduler as Peter mentioned. >> >> Based on previous tests, we have concluded that main drawback of the >> (now removed) old power scheduler was that we had no way to make >> difference between short and long running tasks whereas it's a key >> input (at least for phone) for deciding to pack tasks and for >> selecting the core on an asymmetric system. > > > It is hard to estimate future in general view point. but from hack > point, maybe you can add something to hint this from task_struct. :) > per-task load tracking patchsets give you a good view of the last dozen of ms >> One additional key information is the power distribution in the system >> which can have a finer granularity than current sched_domain >> description. Peter's proposal was to use a SHARE_POWERLINE flag >> similarly to flags that already describe if a sched_domain share >> resources or cpu capacity. > > > Seems I missed this. what's difference with current SD_SHARE_CPUPOWER > and SD_SHARE_PKG_RESOURCES. SD_SHARE_CPUPOWER is set in a sched domain at SMT level (sharing some part of the physical core) SD_SHARE_PKG_RESOURCES is set at MC level (sharing some resources like cache and memory access) > >> >> With these 2 new information, we can have a 1st power saving scheduler >> which spread or packed tasks across core and package > > > Fine, I like to test them on X86, plus SMT and NUMA :) > >> >> Vincent > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/