From nobody Sat Feb 7 07:25:46 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 5BE8FEB64DA for ; Tue, 4 Jul 2023 12:04:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229603AbjGDMEe (ORCPT ); Tue, 4 Jul 2023 08:04:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55278 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229662AbjGDMEc (ORCPT ); Tue, 4 Jul 2023 08:04:32 -0400 Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [45.249.212.189]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E6EB9E7E; Tue, 4 Jul 2023 05:03:58 -0700 (PDT) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.55]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4QwLws1dBlzLmsg; Tue, 4 Jul 2023 20:01:17 +0800 (CST) Received: from huawei.com (10.174.151.185) by canpemm500002.china.huawei.com (7.192.104.244) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.27; Tue, 4 Jul 2023 20:03:28 +0800 From: Miaohe Lin To: , , , CC: , , Subject: [PATCH] cgroup/cpuset: avoid unneeded cpuset_mutex re-lock Date: Tue, 4 Jul 2023 20:03:52 +0800 Message-ID: <20230704120352.1226787-1-linmiaohe@huawei.com> X-Mailer: git-send-email 2.33.0 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Originating-IP: [10.174.151.185] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To canpemm500002.china.huawei.com (7.192.104.244) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" cpuset_mutex unlock and lock pair is only needed when transferring tasks out of empty cpuset. Avoid unneeded cpuset_mutex re-lock when !is_empty to save cpu cycles. Signed-off-by: Miaohe Lin Reviewed-by: Waiman Long --- kernel/cgroup/cpuset.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 601c40da8e03..e136269c152c 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -3521,17 +3521,16 @@ hotplug_update_tasks_legacy(struct cpuset *cs, is_empty =3D cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed); =20 - mutex_unlock(&cpuset_mutex); - /* * Move tasks to the nearest ancestor with execution resources, * This is full cgroup operation which will also call back into * cpuset. Should be done outside any lock. */ - if (is_empty) + if (is_empty) { + mutex_unlock(&cpuset_mutex); remove_tasks_in_empty_cpuset(cs); - - mutex_lock(&cpuset_mutex); + mutex_lock(&cpuset_mutex); + } } =20 static void --=20 2.33.0