Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752527Ab3EIIbT (ORCPT ); Thu, 9 May 2013 04:31:19 -0400 Received: from mga01.intel.com ([192.55.52.88]:7776 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751494Ab3EIIbR (ORCPT ); Thu, 9 May 2013 04:31:17 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.87,639,1363158000"; d="scan'208";a="334826622" Message-ID: <518B5EC9.1030605@intel.com> Date: Thu, 09 May 2013 16:31:05 +0800 From: Alex Shi User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130329 Thunderbird/17.0.5 MIME-Version: 1.0 To: Paul Turner CC: Ingo Molnar , Peter Zijlstra , Thomas Gleixner , Andrew Morton , Borislav Petkov , Namhyung Kim , Mike Galbraith , Morten Rasmussen , Vincent Guittot , Preeti U Murthy , Viresh Kumar , LKML , Mel Gorman , Rik van Riel , Michael Wang Subject: Re: [PATCH v5 3/7] sched: set initial value of runnable avg for new forked task References: <1367804711-30308-1-git-send-email-alex.shi@intel.com> <1367804711-30308-4-git-send-email-alex.shi@intel.com> <5187760D.8060900@intel.com> <51886460.3020009@intel.com> <51887404.4060102@intel.com> <51888B2D.30901@intel.com> In-Reply-To: <51888B2D.30901@intel.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4054 Lines: 118 > > Here is the patch according to Paul's opinions. > just refer the __update_task_entity_contrib in sched.h looks ugly. > comments are appreciated! Paul, With sched_slice, we need to set the runnable avg sum/period after new task assigned to a specific CPU. So, set them __sched_fork is meaningless. and then __update_task_entity_contrib(&p->se) also no reason to use. I am going to pick up the old patch and drop this one. that also avoid to declare it in sched.h. What's your comment of this? Regards! > > --- > From 647404447c996507b6a94110ed13fd122e4ee154 Mon Sep 17 00:00:00 2001 > From: Alex Shi > Date: Mon, 3 Dec 2012 17:30:39 +0800 > Subject: [PATCH 3/7] sched: set initial value of runnable avg for new forked > task > > We need initialize the se.avg.{decay_count, load_avg_contrib} for a > new forked task. > Otherwise random values of above variables cause mess when do new task > enqueue: > enqueue_task_fair > enqueue_entity > enqueue_entity_load_avg > > and make forking balancing imbalance since incorrect load_avg_contrib. > > set avg.decay_count = 0, and give initial value of runnable_avg_sum/period > to resolve such issues. > > Thanks for Pual's suggestions > > Signed-off-by: Alex Shi > --- > kernel/sched/core.c | 8 +++++++- > kernel/sched/fair.c | 4 ++++ > kernel/sched/sched.h | 1 + > 3 files changed, 12 insertions(+), 1 deletion(-) > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index c8db984..4e78de1 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -1566,6 +1566,11 @@ static void __sched_fork(struct task_struct *p) > #ifdef CONFIG_SMP > p->se.avg.runnable_avg_period = 0; > p->se.avg.runnable_avg_sum = 0; > + p->se.avg.decay_count = 0; > + /* New forked task assumed with full utilization */ > + p->se.avg.runnable_avg_period = 1024; > + p->se.avg.runnable_avg_sum = 1024; > + __update_task_entity_contrib(&p->se); > #endif > #ifdef CONFIG_SCHEDSTATS > memset(&p->se.statistics, 0, sizeof(p->se.statistics)); > @@ -1619,7 +1624,6 @@ void sched_fork(struct task_struct *p) > unsigned long flags; > int cpu = get_cpu(); > > - __sched_fork(p); > /* > * We mark the process as running here. This guarantees that > * nobody will actually run it, and a signal or other external > @@ -1653,6 +1657,8 @@ void sched_fork(struct task_struct *p) > p->sched_reset_on_fork = 0; > } > > + __sched_fork(p); > + > if (!rt_prio(p->prio)) > p->sched_class = &fair_sched_class; > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 9c2f726..2881d42 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -1508,6 +1508,10 @@ static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq, > * We track migrations using entity decay_count <= 0, on a wake-up > * migration we use a negative decay count to track the remote decays > * accumulated while sleeping. > + * > + * When enqueue a new forked task, the se->avg.decay_count == 0, so > + * we bypass update_entity_load_avg(), use avg.load_avg_contrib initial > + * value: se->load.weight. > */ > if (unlikely(se->avg.decay_count <= 0)) { > se->avg.last_runnable_update = rq_of(cfs_rq)->clock_task; > diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h > index c6634f1..ec4cb9b 100644 > --- a/kernel/sched/sched.h > +++ b/kernel/sched/sched.h > @@ -876,6 +876,7 @@ extern const struct sched_class idle_sched_class; > extern void trigger_load_balance(struct rq *rq, int cpu); > extern void idle_balance(int this_cpu, struct rq *this_rq); > > +extern inline void __update_task_entity_contrib(struct sched_entity *se); > #else /* CONFIG_SMP */ > > static inline void idle_balance(int cpu, struct rq *rq) > -- Thanks Alex -- 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/