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=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 1AE31C10F03 for ; Tue, 23 Apr 2019 16:18:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C92F8217D9 for ; Tue, 23 Apr 2019 16:18:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=digitalocean.com header.i=@digitalocean.com header.b="B53WkAHs" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728718AbfDWQSx (ORCPT ); Tue, 23 Apr 2019 12:18:53 -0400 Received: from mail-it1-f196.google.com ([209.85.166.196]:51752 "EHLO mail-it1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728681AbfDWQSv (ORCPT ); Tue, 23 Apr 2019 12:18:51 -0400 Received: by mail-it1-f196.google.com with SMTP id s3so1150084itk.1 for ; Tue, 23 Apr 2019 09:18:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=digitalocean.com; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :in-reply-to:references; bh=RRPprdHBeVV/4+2VLyUELzA44hhF2F4q9ugJ+BrPTCk=; b=B53WkAHsZGpYMiWdtVp+UPcGMiqnsXJK8MEuGNJ6j7TGXAaYEY5FYn5tpp0UDqY9VQ KEruhMOpRKV0NwOwFKa3iIbNjBCESZv+21dh+9+IpjMa8lAEunvt43/2/G4EMXKDDYAY nPhR2zyEj8fZ7gf8Jfb4TqURwGuM4aL7DSs00= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:in-reply-to:references; bh=RRPprdHBeVV/4+2VLyUELzA44hhF2F4q9ugJ+BrPTCk=; b=jg6gfBUfXcQh5acQixtLMVbNR51PaVUztqp898jnU7ElLO9nQWMM49exVaEktXwfDe +Ofrk8p3Jeaa+/12tYO/zWkao9zrGJkgV3DD5u1snBOLt2X2EX5Roxq291HpbKNOOIQB y1zpdCriGmvI1Khvp9mla5W+pVubOGvvlWVmRAJjRgK01HYj9jozPPBZqgePXX1ohkWQ 4loXoyEiV/bF8wJWEOJzhiiEWbVwrlb2osVcs/6dzvpIY+WTEtPZfLNu2chTP7pI+5MW LraFOSbkAQSHiTDaRYYY0n7hm8mWSlXIUgzrLGrd4O0ktTE0R3AgAJyPn8veYtixViKN LaaQ== X-Gm-Message-State: APjAAAWmtsKi4s2RdZTlXY8oqcer8bbJbcA+BQuEtCzWQfV9YnSntN4O Xcu0MZGh2Ce/b3Xu0l1OyEynzA== X-Google-Smtp-Source: APXvYqyvQIdj/NG3X4wVD8KVexssvMGSCUKJcSva7fjAwDCx41Ics06H9yrDZPAx1Nds/OLuLnm30w== X-Received: by 2002:a24:b302:: with SMTP id e2mr3019298itf.159.1556036329913; Tue, 23 Apr 2019 09:18:49 -0700 (PDT) Received: from swap-tester ([178.128.225.14]) by smtp.gmail.com with ESMTPSA id n4sm5401687ioh.52.2019.04.23.09.18.49 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 23 Apr 2019 09:18:49 -0700 (PDT) From: Vineeth Remanan Pillai To: Nishanth Aravamudan , Julien Desfossez , Peter Zijlstra , Tim Chen , mingo@kernel.org, tglx@linutronix.de, pjt@google.com, torvalds@linux-foundation.org Cc: linux-kernel@vger.kernel.org, subhra.mazumdar@oracle.com, fweisbec@gmail.com, keescook@chromium.org, kerrnel@google.com, Phil Auld , Aaron Lu , Aubrey Li , Valentin Schneider , Mel Gorman , Pawan Gupta , Paolo Bonzini , Vineeth Remanan Pillai Subject: [RFC PATCH v2 09/17] sched: Introduce sched_class::pick_task() Date: Tue, 23 Apr 2019 16:18:14 +0000 Message-Id: X-Mailer: git-send-email 2.17.1 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Peter Zijlstra (Intel)" Because sched_class::pick_next_task() also implies sched_class::set_next_task() (and possibly put_prev_task() and newidle_balance) it is not state invariant. This makes it unsuitable for remote task selection. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Vineeth Remanan Pillai Signed-off-by: Julien Desfossez --- Changes in v2 ------------- - Fixes a NULL pointer dereference crash - Subhra Mazumdar - Tim Chen --- kernel/sched/deadline.c | 21 ++++++++++++++++----- kernel/sched/fair.c | 39 ++++++++++++++++++++++++++++++++++++--- kernel/sched/idle.c | 10 +++++++++- kernel/sched/rt.c | 21 ++++++++++++++++----- kernel/sched/sched.h | 2 ++ kernel/sched/stop_task.c | 21 ++++++++++++++++----- 6 files changed, 95 insertions(+), 19 deletions(-) diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 249310e68592..010234908cc0 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1723,15 +1723,12 @@ static struct sched_dl_entity *pick_next_dl_entity(struct rq *rq, return rb_entry(left, struct sched_dl_entity, rb_node); } -static struct task_struct * -pick_next_task_dl(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) +static struct task_struct *pick_task_dl(struct rq *rq) { struct sched_dl_entity *dl_se; struct task_struct *p; struct dl_rq *dl_rq; - WARN_ON_ONCE(prev || rf); - dl_rq = &rq->dl; if (unlikely(!dl_rq->dl_nr_running)) @@ -1742,7 +1739,19 @@ pick_next_task_dl(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) p = dl_task_of(dl_se); - set_next_task_dl(rq, p); + return p; +} + +static struct task_struct * +pick_next_task_dl(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) +{ + struct task_struct *p; + + WARN_ON_ONCE(prev || rf); + + p = pick_task_dl(rq); + if (p) + set_next_task_dl(rq, p); return p; } @@ -2389,6 +2398,8 @@ const struct sched_class dl_sched_class = { .set_next_task = set_next_task_dl, #ifdef CONFIG_SMP + .pick_task = pick_task_dl, + .select_task_rq = select_task_rq_dl, .migrate_task_rq = migrate_task_rq_dl, .set_cpus_allowed = set_cpus_allowed_dl, diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index c055bad249a9..45d86b862750 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4132,7 +4132,7 @@ pick_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *curr) * Avoid running the skip buddy, if running something else can * be done without getting too unfair. */ - if (cfs_rq->skip == se) { + if (cfs_rq->skip && cfs_rq->skip == se) { struct sched_entity *second; if (se == curr) { @@ -4150,13 +4150,13 @@ pick_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *curr) /* * Prefer last buddy, try to return the CPU to a preempted task. */ - if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1) + if (left && cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1) se = cfs_rq->last; /* * Someone really wants this to run. If it's not unfair, run it. */ - if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) < 1) + if (left && cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) < 1) se = cfs_rq->next; clear_buddies(cfs_rq, se); @@ -6937,6 +6937,37 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_ set_last_buddy(se); } +static struct task_struct * +pick_task_fair(struct rq *rq) +{ + struct cfs_rq *cfs_rq = &rq->cfs; + struct sched_entity *se; + + if (!cfs_rq->nr_running) + return NULL; + + do { + struct sched_entity *curr = cfs_rq->curr; + + se = pick_next_entity(cfs_rq, NULL); + + if (!(se || curr)) + return NULL; + + if (curr) { + if (se && curr->on_rq) + update_curr(cfs_rq); + + if (!se || entity_before(curr, se)) + se = curr; + } + + cfs_rq = group_cfs_rq(se); + } while (cfs_rq); + + return task_of(se); +} + static struct task_struct * pick_next_task_fair(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) { @@ -10648,6 +10679,8 @@ const struct sched_class fair_sched_class = { .set_next_task = set_next_task_fair, #ifdef CONFIG_SMP + .pick_task = pick_task_fair, + .select_task_rq = select_task_rq_fair, .migrate_task_rq = migrate_task_rq_fair, diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c index 7ece8e820b5d..e7f38da60373 100644 --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -373,6 +373,12 @@ static void check_preempt_curr_idle(struct rq *rq, struct task_struct *p, int fl resched_curr(rq); } +static struct task_struct * +pick_task_idle(struct rq *rq) +{ + return rq->idle; +} + static void put_prev_task_idle(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) { } @@ -386,11 +392,12 @@ static void set_next_task_idle(struct rq *rq, struct task_struct *next) static struct task_struct * pick_next_task_idle(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) { - struct task_struct *next = rq->idle; + struct task_struct *next; if (prev) put_prev_task(rq, prev); + next = pick_task_idle(rq); set_next_task_idle(rq, next); return next; @@ -458,6 +465,7 @@ const struct sched_class idle_sched_class = { .set_next_task = set_next_task_idle, #ifdef CONFIG_SMP + .pick_task = pick_task_idle, .select_task_rq = select_task_rq_idle, .set_cpus_allowed = set_cpus_allowed_common, #endif diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 79f2e60516ef..81557224548c 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -1548,20 +1548,29 @@ static struct task_struct *_pick_next_task_rt(struct rq *rq) return rt_task_of(rt_se); } -static struct task_struct * -pick_next_task_rt(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) +static struct task_struct *pick_task_rt(struct rq *rq) { struct task_struct *p; struct rt_rq *rt_rq = &rq->rt; - WARN_ON_ONCE(prev || rf); - if (!rt_rq->rt_queued) return NULL; p = _pick_next_task_rt(rq); - set_next_task_rt(rq, p); + return p; +} + +static struct task_struct * +pick_next_task_rt(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) +{ + struct task_struct *p; + + WARN_ON_ONCE(prev || rf); + + p = pick_task_rt(rq); + if (p) + set_next_task_rt(rq, p); return p; } @@ -2364,6 +2373,8 @@ const struct sched_class rt_sched_class = { .set_next_task = set_next_task_rt, #ifdef CONFIG_SMP + .pick_task = pick_task_rt, + .select_task_rq = select_task_rq_rt, .set_cpus_allowed = set_cpus_allowed_common, diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 460dd04e76af..a024dd80eeb3 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1682,6 +1682,8 @@ struct sched_class { void (*set_next_task)(struct rq *rq, struct task_struct *p); #ifdef CONFIG_SMP + struct task_struct * (*pick_task)(struct rq *rq); + int (*select_task_rq)(struct task_struct *p, int task_cpu, int sd_flag, int flags); void (*migrate_task_rq)(struct task_struct *p, int new_cpu); diff --git a/kernel/sched/stop_task.c b/kernel/sched/stop_task.c index 7e1cee4e65b2..fb6c436cba6c 100644 --- a/kernel/sched/stop_task.c +++ b/kernel/sched/stop_task.c @@ -29,20 +29,30 @@ static void set_next_task_stop(struct rq *rq, struct task_struct *stop) } static struct task_struct * -pick_next_task_stop(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) +pick_task_stop(struct rq *rq) { struct task_struct *stop = rq->stop; - WARN_ON_ONCE(prev || rf); - if (!stop || !task_on_rq_queued(stop)) return NULL; - set_next_task_stop(rq, stop); - return stop; } +static struct task_struct * +pick_next_task_stop(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) +{ + struct task_struct *p; + + WARN_ON_ONCE(prev || rf); + + p = pick_task_stop(rq); + if (p) + set_next_task_stop(rq, p); + + return p; +} + static void enqueue_task_stop(struct rq *rq, struct task_struct *p, int flags) { @@ -129,6 +139,7 @@ const struct sched_class stop_sched_class = { .set_next_task = set_next_task_stop, #ifdef CONFIG_SMP + .pick_task = pick_task_stop, .select_task_rq = select_task_rq_stop, .set_cpus_allowed = set_cpus_allowed_common, #endif -- 2.17.1