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 6B541C83F16 for ; Mon, 28 Aug 2023 10:47:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231915AbjH1Kqx (ORCPT ); Mon, 28 Aug 2023 06:46:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46462 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231918AbjH1KqW (ORCPT ); Mon, 28 Aug 2023 06:46:22 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CB53C12D for ; Mon, 28 Aug 2023 03:45:57 -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 A84506412D for ; Mon, 28 Aug 2023 10:45:54 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B70E1C433C7; Mon, 28 Aug 2023 10:45:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1693219554; bh=UCH6at7pqT3cw/jreFYEcF0lQ9/DxbP7n6e8CKKKk64=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mDGfq7R0gpS4LKwJDne/ogo83BNFw0WItKhz42MdSZkFKkFOT2nYfcZtOGceexvyF nK2Fg2S+oCKy3aCKmgZAbFLuW+hFtPo2SMti+yZ3bgf3U16pMzpZ0taaK9UFkNI0xZ VHkKXtu743jPG/d1sjc8TtKAS2RtwZtTlPgzF7Is= 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 5.15 77/89] cgroup/cpuset: Iterate only if DEADLINE tasks are present Date: Mon, 28 Aug 2023 12:14:18 +0200 Message-ID: <20230828101152.809970505@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20230828101150.163430842@linuxfoundation.org> References: <20230828101150.163430842@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 5.15-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 @@ -966,6 +966,9 @@ 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)))