From nobody Sun Apr 26 21:37:44 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BC2F5C433EF for ; Wed, 22 Jun 2022 09:48:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1356474AbiFVJsp (ORCPT ); Wed, 22 Jun 2022 05:48:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44184 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1356083AbiFVJsn (ORCPT ); Wed, 22 Jun 2022 05:48:43 -0400 Received: from mail-pf1-x42e.google.com (mail-pf1-x42e.google.com [IPv6:2607:f8b0:4864:20::42e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C9DD6393F8 for ; Wed, 22 Jun 2022 02:48:40 -0700 (PDT) Received: by mail-pf1-x42e.google.com with SMTP id s37so15592408pfg.11 for ; Wed, 22 Jun 2022 02:48:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=R27fWiAoBnC3vGUWaNaOv436L3kAcWhWsTn/Ocs6F18=; b=WQWtT2+J0m8ko5b7iCWlW7QBdK8XHJ/KgG12dJ3baTUPoK/cbTyDSJiyJsoP7k7YR1 nOkvWjMUOSO/VTAe/y5QMWQx2bksU/gJLmO9JYHFBbYKDqSOvfCO2A2FXw11pqRu3wz2 WeeHLDO50dD1i2uPP9voJz/a+DcXmce+EVaIR661dn1z57yVGOpOqxlLu0AtaZSd8uJt +DHxQR0ZYz0ch41sZaW48I/w+er/H346XBkjNi8cNFGgfmnT7O8N3llciQbmC9BHI8kP yKrgC/rdV7K4hYWMk01WpWGM4smT/ufSp+/MVIVWvqcX/XkEDPn5EPI1sKWS4s7XUsDi DTfg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=R27fWiAoBnC3vGUWaNaOv436L3kAcWhWsTn/Ocs6F18=; b=mxLvO4RFU45YrZ82E384ZBmayMpjEAEtIt1Qz1tIx1GsNV40nvqeVHmD6TOst8Kw0l aqhSTN6CqiF2i4Q8Qi4T0T/Gxrzs+c+HoHHQgAJxd/jog/twj8TqybekTEOw9aUEQv4a Y8CIIlOFo/JJxAXkqORMAyTHtKXn1gChTuVJEJsCFx3bOqTfMatqnSW7TEKGRnogG085 giJRKRmwsrvV8Ppwy5oLzHFAtKh3Sv+Fgot9uA1Jdj22JRArBVvg89yV6G2M21PwsVVv App0uL3FrZKe6CF4jrBMHGnON/TYurk0/mkBHTNAW+Q9TaMWacZHl0o26HUw14HxBOK/ Aerg== X-Gm-Message-State: AJIora+6bfwqpQo+RH3/RB+D64MOeD++FnwlqvP/RY+sUbN8COePGzGQ 07u3G5o4ggkRVTLiKWaqNK2HUg== X-Google-Smtp-Source: AGRyM1tmwDyNp5XGrCkS2PZlNEL6pS4hPc5q0aB5She9c3hvkZK9VCHedKjPrY56n8sL8Ra1vp8clw== X-Received: by 2002:a05:6a00:10c3:b0:525:40fe:6e8d with SMTP id d3-20020a056a0010c300b0052540fe6e8dmr4954915pfu.38.1655891320315; Wed, 22 Jun 2022 02:48:40 -0700 (PDT) Received: from C02CV1DAMD6P.bytedance.net ([139.177.225.230]) by smtp.gmail.com with ESMTPSA id m4-20020a17090a858400b001ec7954ae08sm2071452pjn.2.2022.06.22.02.48.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 22 Jun 2022 02:48:39 -0700 (PDT) From: Chengming Zhou To: mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, rdunlap@infradead.org, vschneid@redhat.com Cc: linux-kernel@vger.kernel.org, Chengming Zhou Subject: [PATCH] sched: remove redundant cpu_cgrp_subsys->fork() Date: Wed, 22 Jun 2022 17:48:31 +0800 Message-Id: <20220622094831.22948-1-zhouchengming@bytedance.com> X-Mailer: git-send-email 2.35.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" We use cpu_cgrp_subsys->fork() to set task group for the new fair task in cgroup_post_fork(). Since commit b1e8206582f9 ("sched: Fix yet more sched_fork() races") has already set task group for the new fair task in sched_cgroup_fork(), so cpu_cgrp_subsys->fork() can be removed. cgroup_can_fork() --> pin parent's sched_task_group sched_cgroup_fork() __set_task_cpu --> set task group cgroup_post_fork() ss->fork() :=3D cpu_cgroup_fork() --> set again After this change, task_change_group_fair() only need to care about task cgroup migration, make the code much simplier. This patch move the task se depth setting to set_task_rq(), which is called when task moves across CPUs/groups, is a better place than attach_entity_cfs_rq(). The latter is also used when change task's sched_class, in which case the group/depth doesn't change actually. Signed-off-by: Chengming Zhou Reviewed-by: Vincent Guittot --- kernel/sched/core.c | 27 ++++----------------------- kernel/sched/fair.c | 31 +------------------------------ kernel/sched/sched.h | 6 ++---- 3 files changed, 7 insertions(+), 57 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index c16f8cc5de08..f44bc5b889ab 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -481,8 +481,7 @@ sched_core_dequeue(struct rq *rq, struct task_struct *p= , int flags) { } * p->se.load, p->rt_priority, * p->dl.dl_{runtime, deadline, period, flags, bw, density} * - sched_setnuma(): p->numa_preferred_nid - * - sched_move_task()/ - * cpu_cgroup_fork(): p->sched_task_group + * - sched_move_task(): p->sched_task_group * - uclamp_update_active() p->uclamp* * * p->state <- TASK_*: @@ -10098,7 +10097,7 @@ void sched_release_group(struct task_group *tg) spin_unlock_irqrestore(&task_group_lock, flags); } =20 -static void sched_change_group(struct task_struct *tsk, int type) +static void sched_change_group(struct task_struct *tsk) { struct task_group *tg; =20 @@ -10114,7 +10113,7 @@ static void sched_change_group(struct task_struct *= tsk, int type) =20 #ifdef CONFIG_FAIR_GROUP_SCHED if (tsk->sched_class->task_change_group) - tsk->sched_class->task_change_group(tsk, type); + tsk->sched_class->task_change_group(tsk); else #endif set_task_rq(tsk, task_cpu(tsk)); @@ -10145,7 +10144,7 @@ void sched_move_task(struct task_struct *tsk) if (running) put_prev_task(rq, tsk); =20 - sched_change_group(tsk, TASK_MOVE_GROUP); + sched_change_group(tsk); =20 if (queued) enqueue_task(rq, tsk, queue_flags); @@ -10223,23 +10222,6 @@ static void cpu_cgroup_css_free(struct cgroup_subs= ys_state *css) sched_unregister_group(tg); } =20 -/* - * This is called before wake_up_new_task(), therefore we really only - * have to set its group bits, all the other stuff does not apply. - */ -static void cpu_cgroup_fork(struct task_struct *task) -{ - struct rq_flags rf; - struct rq *rq; - - rq =3D task_rq_lock(task, &rf); - - update_rq_clock(rq); - sched_change_group(task, TASK_SET_GROUP); - - task_rq_unlock(rq, task, &rf); -} - static int cpu_cgroup_can_attach(struct cgroup_taskset *tset) { struct task_struct *task; @@ -11136,7 +11118,6 @@ struct cgroup_subsys cpu_cgrp_subsys =3D { .css_released =3D cpu_cgroup_css_released, .css_free =3D cpu_cgroup_css_free, .css_extra_stat_show =3D cpu_extra_stat_show, - .fork =3D cpu_cgroup_fork, .can_attach =3D cpu_cgroup_can_attach, .attach =3D cpu_cgroup_attach, .legacy_cftypes =3D cpu_legacy_files, diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 8bed75757e65..fdb9125fe34e 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -11325,14 +11325,6 @@ static void attach_entity_cfs_rq(struct sched_enti= ty *se) { struct cfs_rq *cfs_rq =3D cfs_rq_of(se); =20 -#ifdef CONFIG_FAIR_GROUP_SCHED - /* - * Since the real-depth could have been changed (only FAIR - * class maintain depth value), reset depth properly. - */ - se->depth =3D se->parent ? se->parent->depth + 1 : 0; -#endif - /* Synchronize entity with its cfs_rq */ update_load_avg(cfs_rq, se, sched_feat(ATTACH_AGE_LOAD) ? 0 : SKIP_AGE_LO= AD); attach_entity_load_avg(cfs_rq, se); @@ -11431,15 +11423,7 @@ void init_cfs_rq(struct cfs_rq *cfs_rq) } =20 #ifdef CONFIG_FAIR_GROUP_SCHED -static void task_set_group_fair(struct task_struct *p) -{ - struct sched_entity *se =3D &p->se; - - set_task_rq(p, task_cpu(p)); - se->depth =3D se->parent ? se->parent->depth + 1 : 0; -} - -static void task_move_group_fair(struct task_struct *p) +static void task_change_group_fair(struct task_struct *p) { detach_task_cfs_rq(p); set_task_rq(p, task_cpu(p)); @@ -11451,19 +11435,6 @@ static void task_move_group_fair(struct task_struc= t *p) attach_task_cfs_rq(p); } =20 -static void task_change_group_fair(struct task_struct *p, int type) -{ - switch (type) { - case TASK_SET_GROUP: - task_set_group_fair(p); - break; - - case TASK_MOVE_GROUP: - task_move_group_fair(p); - break; - } -} - void free_fair_sched_group(struct task_group *tg) { int i; diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 317480d535b0..8433e22da3ab 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1901,6 +1901,7 @@ static inline void set_task_rq(struct task_struct *p,= unsigned int cpu) set_task_rq_fair(&p->se, p->se.cfs_rq, tg->cfs_rq[cpu]); p->se.cfs_rq =3D tg->cfs_rq[cpu]; p->se.parent =3D tg->se[cpu]; + p->se.depth =3D tg->se[cpu] ? tg->se[cpu]->depth + 1 : 0; #endif =20 #ifdef CONFIG_RT_GROUP_SCHED @@ -2163,11 +2164,8 @@ struct sched_class { =20 void (*update_curr)(struct rq *rq); =20 -#define TASK_SET_GROUP 0 -#define TASK_MOVE_GROUP 1 - #ifdef CONFIG_FAIR_GROUP_SCHED - void (*task_change_group)(struct task_struct *p, int type); + void (*task_change_group)(struct task_struct *p); #endif }; =20 --=20 2.36.1