From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from LGEAMRELO12.lge.com ([156.147.23.52]:48426 "EHLO lgeamrelo12.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751961AbcAEJQo (ORCPT ); Tue, 5 Jan 2016 04:16:44 -0500 From: Byungchul Park To: stable@vger.kernel.org Cc: peterz@infradead.org, linux-kernel@vger.kernel.org, ktkhai@parallels.com, rostedt@goodmis.org, juri.lelli@gmail.com, pang.xunlei@linaro.org, oleg@redhat.com, wanpeng.li@linux.intel.com, umgwanakikbuti@gmail.com, Thomas Gleixner Subject: [PATCH for v3.14.58 4/7] sched,rt: Remove return value from pull_rt_task() Date: Tue, 5 Jan 2016 18:16:25 +0900 Message-Id: <1451985388-19492-4-git-send-email-byungchul.park@lge.com> In-Reply-To: <1451985388-19492-1-git-send-email-byungchul.park@lge.com> References: <20160105085211.GB3621@X58A-UD3R> <1451985388-19492-1-git-send-email-byungchul.park@lge.com> Sender: stable-owner@vger.kernel.org List-ID: From: Peter Zijlstra In order to be able to use pull_rt_task() from a callback, we need to do away with the return value. Since the return value indicates if we should reschedule, do this inside the function. Since not all callers currently do this, this can increase the number of reschedules due rt balancing. Too many reschedules is not a correctness issues, too few are. Signed-off-by: Peter Zijlstra (Intel) Cc: ktkhai@parallels.com Cc: rostedt@goodmis.org Cc: juri.lelli@gmail.com Cc: pang.xunlei@linaro.org Cc: oleg@redhat.com Cc: wanpeng.li@linux.intel.com Cc: umgwanakikbuti@gmail.com Link: http://lkml.kernel.org/r/20150611124742.679002000@infradead.org Signed-off-by: Thomas Gleixner Signed-off-by: Byungchul Park Conflicts: kernel/sched/rt.c --- kernel/sched/rt.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 2b980d0..d235fd7 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -1652,14 +1652,15 @@ static void push_rt_tasks(struct rq *rq) ; } -static int pull_rt_task(struct rq *this_rq) +static void pull_rt_task(struct rq *this_rq) { - int this_cpu = this_rq->cpu, ret = 0, cpu; + int this_cpu = this_rq->cpu, cpu; + bool resched = false; struct task_struct *p; struct rq *src_rq; if (likely(!rt_overloaded(this_rq))) - return 0; + return; /* * Match the barrier from rt_set_overloaded; this guarantees that if we @@ -1716,7 +1717,7 @@ static int pull_rt_task(struct rq *this_rq) if (p->prio < src_rq->curr->prio) goto skip; - ret = 1; + resched = true; deactivate_task(src_rq, p, 0); set_task_cpu(p, this_cpu); @@ -1732,7 +1733,8 @@ skip: double_unlock_balance(this_rq, src_rq); } - return ret; + if (resched) + resched_task(this_rq->curr); } static void pre_schedule_rt(struct rq *rq, struct task_struct *prev) @@ -1835,8 +1837,7 @@ static void switched_from_rt(struct rq *rq, struct task_struct *p) if (!p->on_rq || rq->rt.rt_nr_running) return; - if (pull_rt_task(rq)) - resched_task(rq->curr); + pull_rt_task(rq); } void init_sched_rt_class(void) -- 1.9.1