From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,UNWANTED_LANGUAGE_BODY autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A6A65C43331 for ; Mon, 11 Nov 2019 09:33:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 78A1020818 for ; Mon, 11 Nov 2019 09:33:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727296AbfKKJdC (ORCPT ); Mon, 11 Nov 2019 04:33:02 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:55834 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727262AbfKKJdB (ORCPT ); Mon, 11 Nov 2019 04:33:01 -0500 Received: from [5.158.153.53] (helo=tip-bot2.lab.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1iU63m-00038T-RS; Mon, 11 Nov 2019 10:32:35 +0100 Received: from [127.0.1.1] (localhost [IPv6:::1]) by tip-bot2.lab.linutronix.de (Postfix) with ESMTP id 6B4DA1C0093; Mon, 11 Nov 2019 10:32:34 +0100 (CET) Date: Mon, 11 Nov 2019 09:32:34 -0000 From: "tip-bot2 for Peter Zijlstra" Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: sched/core] sched/core: Further clarify sched_class::set_next_task() Cc: "Peter Zijlstra (Intel)" , Linus Torvalds , Thomas Gleixner , bsegall@google.com, dietmar.eggemann@arm.com, juri.lelli@redhat.com, ktkhai@virtuozzo.com, mgorman@suse.de, qais.yousef@arm.com, qperret@google.com, rostedt@goodmis.org, valentin.schneider@arm.com, vincent.guittot@linaro.org, Ingo Molnar , Borislav Petkov , linux-kernel@vger.kernel.org In-Reply-To: <20191108131909.775434698@infradead.org> References: <20191108131909.775434698@infradead.org> MIME-Version: 1.0 Message-ID: <157346475407.29376.10359988629214177511.tip-bot2@tip-bot2> X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the sched/core branch of tip: Commit-ID: a0e813f26ebcb25c0b5e504498fbd796cca1a4ba Gitweb: https://git.kernel.org/tip/a0e813f26ebcb25c0b5e504498fbd796cca1a4ba Author: Peter Zijlstra AuthorDate: Fri, 08 Nov 2019 14:16:00 +01:00 Committer: Ingo Molnar CommitterDate: Mon, 11 Nov 2019 08:35:21 +01:00 sched/core: Further clarify sched_class::set_next_task() It turns out there really is something special to the first set_next_task() invocation. In specific the 'change' pattern really should not cause balance callbacks. Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: bsegall@google.com Cc: dietmar.eggemann@arm.com Cc: juri.lelli@redhat.com Cc: ktkhai@virtuozzo.com Cc: mgorman@suse.de Cc: qais.yousef@arm.com Cc: qperret@google.com Cc: rostedt@goodmis.org Cc: valentin.schneider@arm.com Cc: vincent.guittot@linaro.org Fixes: f95d4eaee6d0 ("sched/{rt,deadline}: Fix set_next_task vs pick_next_task") Link: https://lkml.kernel.org/r/20191108131909.775434698@infradead.org Signed-off-by: Ingo Molnar --- kernel/sched/deadline.c | 7 +++++-- kernel/sched/fair.c | 2 +- kernel/sched/idle.c | 4 ++-- kernel/sched/rt.c | 7 +++++-- kernel/sched/sched.h | 4 ++-- kernel/sched/stop_task.c | 4 ++-- 6 files changed, 17 insertions(+), 11 deletions(-) diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index f7fbb44..43323f8 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1743,13 +1743,16 @@ static void start_hrtick_dl(struct rq *rq, struct task_struct *p) } #endif -static void set_next_task_dl(struct rq *rq, struct task_struct *p) +static void set_next_task_dl(struct rq *rq, struct task_struct *p, bool first) { p->se.exec_start = rq_clock_task(rq); /* You can't push away the running task */ dequeue_pushable_dl_task(rq, p); + if (!first) + return; + if (hrtick_enabled(rq)) start_hrtick_dl(rq, p); @@ -1782,7 +1785,7 @@ static struct task_struct *pick_next_task_dl(struct rq *rq) dl_se = pick_next_dl_entity(rq, dl_rq); BUG_ON(!dl_se); p = dl_task_of(dl_se); - set_next_task_dl(rq, p); + set_next_task_dl(rq, p, true); return p; } diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index ba97d1a..81eba55 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -10344,7 +10344,7 @@ static void switched_to_fair(struct rq *rq, struct task_struct *p) * This routine is mostly called to set cfs_rq->curr field when a task * migrates between groups/classes. */ -static void set_next_task_fair(struct rq *rq, struct task_struct *p) +static void set_next_task_fair(struct rq *rq, struct task_struct *p, bool first) { struct sched_entity *se = &p->se; diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c index f88b79e..428cd05 100644 --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -385,7 +385,7 @@ static void put_prev_task_idle(struct rq *rq, struct task_struct *prev) { } -static void set_next_task_idle(struct rq *rq, struct task_struct *next) +static void set_next_task_idle(struct rq *rq, struct task_struct *next, bool first) { update_idle_core(rq); schedstat_inc(rq->sched_goidle); @@ -395,7 +395,7 @@ struct task_struct *pick_next_task_idle(struct rq *rq) { struct task_struct *next = rq->idle; - set_next_task_idle(rq, next); + set_next_task_idle(rq, next, true); return next; } diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 38027c0..e591d40 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -1515,13 +1515,16 @@ static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p, int flag #endif } -static inline void set_next_task_rt(struct rq *rq, struct task_struct *p) +static inline void set_next_task_rt(struct rq *rq, struct task_struct *p, bool first) { p->se.exec_start = rq_clock_task(rq); /* The running task is never eligible for pushing */ dequeue_pushable_task(rq, p); + if (!first) + return; + /* * If prev task was rt, put_prev_task() has already updated the * utilization. We only care of the case where we start to schedule a @@ -1572,7 +1575,7 @@ static struct task_struct *pick_next_task_rt(struct rq *rq) return NULL; p = _pick_next_task_rt(rq); - set_next_task_rt(rq, p); + set_next_task_rt(rq, p, true); return p; } diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 75d96cc..05c2827 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1716,7 +1716,7 @@ struct sched_class { struct task_struct *(*pick_next_task)(struct rq *rq); void (*put_prev_task)(struct rq *rq, struct task_struct *p); - void (*set_next_task)(struct rq *rq, struct task_struct *p); + void (*set_next_task)(struct rq *rq, struct task_struct *p, bool first); #ifdef CONFIG_SMP int (*balance)(struct rq *rq, struct task_struct *prev, struct rq_flags *rf); @@ -1768,7 +1768,7 @@ static inline void put_prev_task(struct rq *rq, struct task_struct *prev) static inline void set_next_task(struct rq *rq, struct task_struct *next) { WARN_ON_ONCE(rq->curr != next); - next->sched_class->set_next_task(rq, next); + next->sched_class->set_next_task(rq, next, false); } #ifdef CONFIG_SMP diff --git a/kernel/sched/stop_task.c b/kernel/sched/stop_task.c index 0aefdfb..4c9e997 100644 --- a/kernel/sched/stop_task.c +++ b/kernel/sched/stop_task.c @@ -29,7 +29,7 @@ check_preempt_curr_stop(struct rq *rq, struct task_struct *p, int flags) /* we're never preempted */ } -static void set_next_task_stop(struct rq *rq, struct task_struct *stop) +static void set_next_task_stop(struct rq *rq, struct task_struct *stop, bool first) { stop->se.exec_start = rq_clock_task(rq); } @@ -39,7 +39,7 @@ static struct task_struct *pick_next_task_stop(struct rq *rq) if (!sched_stop_runnable(rq)) return NULL; - set_next_task_stop(rq, rq->stop); + set_next_task_stop(rq, rq->stop, true); return rq->stop; }