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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5DAE1C83F16 for ; Mon, 28 Aug 2023 10:35:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231559AbjH1Kei (ORCPT ); Mon, 28 Aug 2023 06:34:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46088 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231607AbjH1KeP (ORCPT ); Mon, 28 Aug 2023 06:34:15 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9D79FB9 for ; Mon, 28 Aug 2023 03:34:05 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 3B9C861DAA for ; Mon, 28 Aug 2023 10:34:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4E7D6C433C7; Mon, 28 Aug 2023 10:34:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1693218844; bh=ktOF3DJMGVCV2S53ojkfSawUT3dchceVW5yGQcF28To=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qf9sO5fiiSVVgShoRG3FwNpi3L/AqZ9Ax3PVK3cs4Ap8Ij88uK5JNeH8BlHZprcSz OBuX/faz4EtcepT+1gV9TA4UKG1zK1D7HNxMz7Ka3ybTrQUI/6VHZ0TRYzWCVJ+L3S PWXY8WUJ8IhBsVZzcdIjz5CvV66x2qmYCQ8jyteo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, "Qais Yousef (Google)" , Juri Lelli , Waiman Long , Tejun Heo Subject: [PATCH 6.1 104/122] cgroup/cpuset: Iterate only if DEADLINE tasks are present Date: Mon, 28 Aug 2023 12:13:39 +0200 Message-ID: <20230828101159.878367935@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20230828101156.480754469@linuxfoundation.org> References: <20230828101156.480754469@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Juri Lelli commit c0f78fd5edcf29b2822ac165f9248a6c165e8554 upstream. update_tasks_root_domain currently iterates over all tasks even if no DEADLINE task is present on the cpuset/root domain for which bandwidth accounting is being rebuilt. This has been reported to introduce 10+ ms delays on suspend-resume operations. Skip the costly iteration for cpusets that don't contain DEADLINE tasks. Reported-by: Qais Yousef (Google) Link: https://lore.kernel.org/lkml/20230206221428.2125324-1-qyousef@layalina.io/ Signed-off-by: Juri Lelli Reviewed-by: Waiman Long Signed-off-by: Tejun Heo Signed-off-by: Qais Yousef (Google) Signed-off-by: Greg Kroah-Hartman --- kernel/cgroup/cpuset.c | 3 +++ 1 file changed, 3 insertions(+) --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -1092,6 +1092,9 @@ static void dl_update_tasks_root_domain( struct css_task_iter it; struct task_struct *task; + if (cs->nr_deadline_tasks == 0) + return; + css_task_iter_start(&cs->css, 0, &it); while ((task = css_task_iter_next(&it)))