From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753412AbbC0PDc (ORCPT ); Fri, 27 Mar 2015 11:03:32 -0400 Received: from eu-smtp-delivery-143.mimecast.com ([207.82.80.143]:62887 "EHLO eu-smtp-delivery-143.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753325AbbC0PD2 convert rfc822-to-8bit (ORCPT ); Fri, 27 Mar 2015 11:03:28 -0400 Message-ID: <5515713C.3060509@arm.com> Date: Fri, 27 Mar 2015 15:03:24 +0000 From: Dietmar Eggemann User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 MIME-Version: 1.0 To: Sai Gurrappadi , Morten Rasmussen , "peterz@infradead.org" , "mingo@redhat.com" CC: "vincent.guittot@linaro.org" , "yuyang.du@intel.com" , "preeti@linux.vnet.ibm.com" , "mturquette@linaro.org" , "nico@linaro.org" , "rjw@rjwysocki.net" , Juri Lelli , "linux-kernel@vger.kernel.org" , Peter Boonstoppel Subject: Re: [RFCv3 PATCH 43/48] sched: Introduce energy awareness into detach_tasks References: <1423074685-6336-1-git-send-email-morten.rasmussen@arm.com> <1423074685-6336-44-git-send-email-morten.rasmussen@arm.com> <551349D0.8070402@nvidia.com> In-Reply-To: <551349D0.8070402@nvidia.com> X-OriginalArrivalTime: 27 Mar 2015 15:03:24.0527 (UTC) FILETIME=[2C40AFF0:01D0689F] X-MC-Unique: tcrqJ2SYQdadnA4hn19XKw-1 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 25/03/15 23:50, Sai Gurrappadi wrote: > On 02/04/2015 10:31 AM, Morten Rasmussen wrote: >> From: Dietmar Eggemann >> while (!list_empty(tasks)) { >> @@ -6121,6 +6121,20 @@ static int detach_tasks(struct lb_env *env) >> if (!can_migrate_task(p, env)) >> goto next; >> >> + if (env->use_ea) { >> + struct energy_env eenv = { >> + .src_cpu = env->src_cpu, >> + .dst_cpu = env->dst_cpu, >> + .usage_delta = task_utilization(p), >> + }; >> + int e_diff = energy_diff(&eenv); >> + >> + if (e_diff >= 0) >> + goto next; >> + >> + goto detach; >> + } >> + >> load = task_h_load(p); >> >> if (sched_feat(LB_MIN) && load < 16 && !env->sd->nr_balance_failed) >> @@ -6129,6 +6143,7 @@ static int detach_tasks(struct lb_env *env) >> if ((load / 2) > env->imbalance) >> goto next; >> >> +detach: >> detach_task(p, env); >> list_add(&p->se.group_node, &env->tasks); > > Hi Morten, Dietmar, > > Wouldn't the above energy_diff() use the 'old' value of dst_cpu's util? > Tasks are detached/dequeued in this loop so they have their util > contrib. removed from src_cpu but their contrib. hasn't been added to > dst_cpu yet (happens in attach_tasks). You're absolutely right Sai. Thanks for pointing this out! I guess I rather have to accumulate the usage of tasks I've detached and add this to the eenv::usage_delta of the energy_diff() call for the next task. Something like this (only slightly tested): diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 8d4cc72f4778..d0d0e965fd0c 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6097,6 +6097,7 @@ static int detach_tasks(struct lb_env *env) struct task_struct *p; unsigned long load = 0; int detached = 0; + int usage_delta = 0; lockdep_assert_held(&env->src_rq->lock); @@ -6122,16 +6123,19 @@ static int detach_tasks(struct lb_env *env) goto next; if (env->use_ea) { + int util = task_utilization(p); struct energy_env eenv = { .src_cpu = env->src_cpu, .dst_cpu = env->dst_cpu, - .usage_delta = task_utilization(p), + .usage_delta = usage_delta + util, }; int e_diff = energy_diff(&eenv); if (e_diff >= 0) goto next; + usage_delta += util; + goto detach; } [...]