From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1423293AbcFMSyr (ORCPT ); Mon, 13 Jun 2016 14:54:47 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:43707 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161331AbcFMShb (ORCPT ); Mon, 13 Jun 2016 14:37:31 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, rostedt@goodmis.org, ktkhai@parallels.com, wanpeng.li@linux.intel.com, oleg@redhat.com, "Thomas Gleixner" , "Byungchul Park" , umgwanakikbuti@gmail.com, juri.lelli@gmail.com, pang.xunlei@linaro.org, "Peter Zijlstra" Date: Mon, 13 Jun 2016 19:36:37 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 113/114] sched,dl: Remove return value from pull_dl_task() In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.36-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Peter Zijlstra commit 0ea60c2054fc3b0c3eb68ac4f6884f3ee78d9925 upstream. In order to be able to use pull_dl_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/20150611124742.859398977@infradead.org Signed-off-by: Thomas Gleixner [Conflicts: kernel/sched/deadline.c] Signed-off-by: Byungchul Park [bwh: Backported to 3.16: use resched_task() instead of resched_curr()] Signed-off-by: Ben Hutchings --- kernel/sched/deadline.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -252,9 +252,8 @@ static inline bool need_pull_dl_task(str return false; } -static inline int pull_dl_task(struct rq *rq) +static inline void pull_dl_task(struct rq *rq) { - return 0; } static inline void queue_push_tasks(struct rq *rq) @@ -957,7 +956,7 @@ static void check_preempt_equal_dl(struc resched_task(rq->curr); } -static int pull_dl_task(struct rq *this_rq); +static void pull_dl_task(struct rq *this_rq); #endif /* CONFIG_SMP */ @@ -1380,15 +1379,16 @@ static void push_dl_tasks(struct rq *rq) ; } -static int pull_dl_task(struct rq *this_rq) +static void pull_dl_task(struct rq *this_rq) { - int this_cpu = this_rq->cpu, ret = 0, cpu; + int this_cpu = this_rq->cpu, cpu; struct task_struct *p; + bool resched = false; struct rq *src_rq; u64 dmin = LONG_MAX; if (likely(!dl_overloaded(this_rq))) - return 0; + return; /* * Match the barrier from dl_set_overloaded; this guarantees that if we @@ -1443,7 +1443,7 @@ static int pull_dl_task(struct rq *this_ src_rq->curr->dl.deadline)) goto skip; - ret = 1; + resched = true; deactivate_task(src_rq, p, 0); set_task_cpu(p, this_cpu); @@ -1456,7 +1456,8 @@ skip: double_unlock_balance(this_rq, src_rq); } - return ret; + if (resched) + resched_task(this_rq->curr); } /*