Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752643Ab3EFBqX (ORCPT ); Sun, 5 May 2013 21:46:23 -0400 Received: from mga02.intel.com ([134.134.136.20]:64038 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752528Ab3EFBqV (ORCPT ); Sun, 5 May 2013 21:46:21 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.87,618,1363158000"; d="scan'208";a="308658613" From: Alex Shi To: mingo@redhat.com, peterz@infradead.org, tglx@linutronix.de, akpm@linux-foundation.org, bp@alien8.de, pjt@google.com, namhyung@kernel.org, efault@gmx.de, morten.rasmussen@arm.com Cc: vincent.guittot@linaro.org, preeti@linux.vnet.ibm.com, viresh.kumar@linaro.org, linux-kernel@vger.kernel.org, alex.shi@intel.com, mgorman@suse.de, riel@redhat.com, wangyun@linux.vnet.ibm.com Subject: [PATCH v5 3/7] sched: set initial value of runnable avg for new forked task Date: Mon, 6 May 2013 09:45:07 +0800 Message-Id: <1367804711-30308-4-git-send-email-alex.shi@intel.com> X-Mailer: git-send-email 1.7.12 In-Reply-To: <1367804711-30308-1-git-send-email-alex.shi@intel.com> References: <1367804711-30308-1-git-send-email-alex.shi@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2227 Lines: 66 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 avg.load_avg_contrib = se->load.weight to resolve such issues. Signed-off-by: Alex Shi --- kernel/sched/core.c | 6 ++++++ kernel/sched/fair.c | 4 ++++ 2 files changed, 10 insertions(+) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index c8db984..ecec7f1 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1566,6 +1566,7 @@ 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; #endif #ifdef CONFIG_SCHEDSTATS memset(&p->se.statistics, 0, sizeof(p->se.statistics)); @@ -1653,6 +1654,11 @@ void sched_fork(struct task_struct *p) p->sched_reset_on_fork = 0; } + /* New forked task assumed with full utilization */ +#if defined(CONFIG_SMP) + p->se.avg.load_avg_contrib = p->se.load.weight; +#endif + 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; -- 1.7.12 -- 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/