From nobody Thu Apr 9 00:19:31 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 82DC2C38A02 for ; Mon, 31 Oct 2022 12:23:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230291AbiJaMXB (ORCPT ); Mon, 31 Oct 2022 08:23:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48768 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231330AbiJaMWt (ORCPT ); Mon, 31 Oct 2022 08:22:49 -0400 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E8D22F02D for ; Mon, 31 Oct 2022 05:22:14 -0700 (PDT) Received: from dggpeml500023.china.huawei.com (unknown [172.30.72.54]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4N1Bwn66ZDz15MHl; Mon, 31 Oct 2022 20:17:13 +0800 (CST) Received: from dggpeml500018.china.huawei.com (7.185.36.186) by dggpeml500023.china.huawei.com (7.185.36.114) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Mon, 31 Oct 2022 20:22:13 +0800 Received: from huawei.com (10.67.174.191) by dggpeml500018.china.huawei.com (7.185.36.186) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Mon, 31 Oct 2022 20:22:13 +0800 From: Zhang Qiao To: , , , CC: , , , , , , , , Subject: [PATCH next 1/2] sched: Init new task's vruntime after select cpu Date: Mon, 31 Oct 2022 20:51:12 +0800 Message-ID: <20221031125113.72980-2-zhangqiao22@huawei.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20221031125113.72980-1-zhangqiao22@huawei.com> References: <20221031125113.72980-1-zhangqiao22@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.67.174.191] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggpeml500018.china.huawei.com (7.185.36.186) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" When create a new task, we initialize vruntime of the new task at sched_cgroup_fork(). However, this action is executed too early and may be incorrect, because it use current cpu to init the vruntime, but the new task actually runs on the cpu assigned at wake_up_new_task(). So the patch call task_fork() after select fork cpu and use the ready cpu(the child will run on it) init the new task. Signed-off-by: Zhang Qiao --- kernel/sched/core.c | 7 ++++++- kernel/sched/fair.c | 7 +------ 2 files changed, 7 insertions(+), 7 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index e4ce124ec701..ca5677206efd 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4627,9 +4627,13 @@ void sched_cgroup_fork(struct task_struct *p, struct= kernel_clone_args *kargs) * so use __set_task_cpu(). */ __set_task_cpu(p, smp_processor_id()); + raw_spin_unlock_irqrestore(&p->pi_lock, flags); +} + +void sched_task_fork(struct task_struct *p) +{ if (p->sched_class->task_fork) p->sched_class->task_fork(p); - raw_spin_unlock_irqrestore(&p->pi_lock, flags); } =20 void sched_post_fork(struct task_struct *p) @@ -4682,6 +4686,7 @@ void wake_up_new_task(struct task_struct *p) #endif rq =3D __task_rq_lock(p, &rf); update_rq_clock(rq); + sched_task_fork(p); post_init_entity_util_avg(p); =20 activate_task(rq, p, ENQUEUE_NOCLOCK); diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index e4a0b8bd941c..34845d425180 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -11603,12 +11603,8 @@ static void task_fork_fair(struct task_struct *p) struct cfs_rq *cfs_rq; struct sched_entity *se =3D &p->se, *curr; struct rq *rq =3D this_rq(); - struct rq_flags rf; =20 - rq_lock(rq, &rf); - update_rq_clock(rq); - - cfs_rq =3D task_cfs_rq(current); + cfs_rq =3D task_cfs_rq(p); curr =3D cfs_rq->curr; if (curr) { update_curr(cfs_rq); @@ -11626,7 +11622,6 @@ static void task_fork_fair(struct task_struct *p) } =20 se->vruntime -=3D cfs_rq->min_vruntime; - rq_unlock(rq, &rf); } =20 /* --=20 2.17.1