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=-3.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS autolearn=no 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 D6AB0C5DF60 for ; Fri, 8 Nov 2019 13:21:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A1F0521D6C for ; Fri, 8 Nov 2019 13:21:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="FcWbjedC" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729911AbfKHNVy (ORCPT ); Fri, 8 Nov 2019 08:21:54 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:59262 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728371AbfKHNVg (ORCPT ); Fri, 8 Nov 2019 08:21:36 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=Content-Type:MIME-Version:References: Subject:Cc:To:From:Date:Message-Id:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=hygrSi0ztJbd+dBSkhH6ffAddwGBz8EoqwwX8uIlEKg=; b=FcWbjedCtVxT9eMmCbXUt5TB3O hNbz5maqjlUJOcixnhbukli4mauHkdIRYMJZYiPg9kUYm8XFa1bs8xFrxkbYsQ4tt2RJL7Qj1kht1 pUgcZaAjUQwg/2BZRTmdXgd0HLXf+jLXqwUMUzVlTbMCwRiCEfkYa1WaWOlM6bxnec2OSx4+ZBKp3 uKv6oRnefMTEwvdLsRurTpldYlMf0QWzeRdwrD9uMDs6F+nEm0t6iJ7O5M0yETfi5BI71gMEJ0MVS pinqVqwTEUTirNgl4xtNAPeEylrtuD/gxywQXLWSn0CXyBX15CO98siuK+wLe3xP99b06JBoxfZXG 7QptLfSA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1iT4Ca-0006lR-Oi; Fri, 08 Nov 2019 13:21:25 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id F2C11306CBC; Fri, 8 Nov 2019 14:20:15 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 0) id 5493620C10EBC; Fri, 8 Nov 2019 14:21:20 +0100 (CET) Message-Id: <20191108131909.775434698@infradead.org> User-Agent: quilt/0.65 Date: Fri, 08 Nov 2019 14:16:00 +0100 From: Peter Zijlstra To: mingo@kernel.org, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, juri.lelli@redhat.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de Cc: linux-kernel@vger.kernel.org, qperret@google.com, valentin.schneider@arm.com, qais.yousef@arm.com, ktkhai@virtuozzo.com, peterz@infradead.org Subject: [PATCH 7/7] sched: Further clarify sched_class::set_next_task() References: <20191108131553.027892369@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Fixes: f95d4eaee6d0 ("sched/{rt,deadline}: Fix set_next_task vs pick_next_task") Signed-off-by: Peter Zijlstra (Intel) --- 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(-) --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1743,13 +1743,16 @@ static void start_hrtick_dl(struct rq *r } #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_tas 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; } --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -10343,7 +10343,7 @@ static void switched_to_fair(struct rq * * 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; --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -385,7 +385,7 @@ static void put_prev_task_idle(struct rq { } -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 task_struct *next = rq->idle; - set_next_task_idle(rq, next); + set_next_task_idle(rq, next, true); return next; } --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -1515,13 +1515,16 @@ static void check_preempt_curr_rt(struct #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_tas return NULL; p = _pick_next_task_rt(rq); - set_next_task_rt(rq, p); + set_next_task_rt(rq, p, true); return p; } --- 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 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 --- a/kernel/sched/stop_task.c +++ b/kernel/sched/stop_task.c @@ -29,7 +29,7 @@ check_preempt_curr_stop(struct rq *rq, s /* 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_tas 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; }