From nobody Sun Feb 8 13:40:01 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 33118EB64D9 for ; Thu, 29 Jun 2023 03:52:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231626AbjF2DwG (ORCPT ); Wed, 28 Jun 2023 23:52:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42432 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232047AbjF2Dv0 (ORCPT ); Wed, 28 Jun 2023 23:51:26 -0400 Received: from mx6.didiglobal.com (mx6.didiglobal.com [111.202.70.123]) by lindbergh.monkeyblade.net (Postfix) with SMTP id CC7D23A81 for ; Wed, 28 Jun 2023 20:51:01 -0700 (PDT) Received: from mail.didiglobal.com (unknown [10.79.65.12]) by mx6.didiglobal.com (Maildata Gateway V2.8) with ESMTPS id 9528711002B827; Thu, 29 Jun 2023 11:50:58 +0800 (CST) Received: from didi-ThinkCentre-M930t-N000 (10.79.64.101) by ZJY02-ACTMBX-02.didichuxing.com (10.79.65.12) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.21; Thu, 29 Jun 2023 11:50:58 +0800 Date: Thu, 29 Jun 2023 11:50:50 +0800 X-MD-Sfrom: tiozhang@didiglobal.com X-MD-SrcIP: 10.79.65.12 From: tiozhang To: , CC: , , , , , , , Subject: [PATCH v5] workqueue: add cmdline parameter `workqueue.unbound_cpus` to further constrain wq_unbound_cpumask at boot time Message-ID: <20230629035050.GA17223@didi-ThinkCentre-M930t-N000> Mail-Followup-To: tj@kernel.org, rdunlap@infradead.org, frederic@kernel.org, jiangshanlai@gmail.com, linux-kernel@vger.kernel.org, zyhtheonly@gmail.com, zyhtheonly@yeah.net, zwp10758@gmail.com, fuyuanli@gmail.com MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) X-Originating-IP: [10.79.64.101] X-ClientProxiedBy: ZJY01-PUBMBX-01.didichuxing.com (10.79.64.32) To ZJY02-ACTMBX-02.didichuxing.com (10.79.65.12) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Motivation of doing this is to better improve boot times for devices when we want to prevent our workqueue works from running on some specific CPUs, e,g, some CPUs are busy with interrupts. Signed-off-by: tiozhang --- Documentation/admin-guide/kernel-parameters.txt | 7 +++++++ kernel/workqueue.c | 17 +++++++++++++++++ 2 files changed, 24 insertions(+) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentatio= n/admin-guide/kernel-parameters.txt index a465d5242774..a88b133ab09b 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -6780,6 +6780,13 @@ disables both lockup detectors. Default is 10 seconds. =20 + workqueue.unbound_cpus=3D + [KNL,SMP] Specify to constrain one or some CPUs + to use in unbound workqueues. + Format: + By default, all online CPUs are available for + unbound workqueues. + workqueue.watchdog_thresh=3D If CONFIG_WQ_WATCHDOG is configured, workqueue can warn stall conditions and dump internal state to diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 7cd5f5e7e0a1..70145031acdb 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -329,6 +329,9 @@ static bool workqueue_freezing; /* PL: have wqs starte= d freezing? */ /* PL: allowable cpus for unbound wqs and work items */ static cpumask_var_t wq_unbound_cpumask; =20 +/* for further constrain wq_unbound_cpumask by cmdline parameter*/ +static struct cpumask wq_cmdline_cpumask __initdata; + /* CPU where unbound work was last round robin scheduled from this CPU */ static DEFINE_PER_CPU(int, wq_rr_cpu_last); =20 @@ -6006,6 +6009,9 @@ void __init workqueue_init_early(void) cpumask_copy(wq_unbound_cpumask, housekeeping_cpumask(HK_TYPE_WQ)); cpumask_and(wq_unbound_cpumask, wq_unbound_cpumask, housekeeping_cpumask(= HK_TYPE_DOMAIN)); =20 + if (!cpumask_empty(&wq_cmdline_cpumask)) + cpumask_and(wq_unbound_cpumask, wq_unbound_cpumask, &wq_cmdline_cpumask); + pwq_cache =3D KMEM_CACHE(pool_workqueue, SLAB_PANIC); =20 /* initialize CPU pools */ @@ -6129,3 +6135,14 @@ void __init workqueue_init(void) */ void __warn_flushing_systemwide_wq(void) { } EXPORT_SYMBOL(__warn_flushing_systemwide_wq); + +static int __init workqueue_unbound_cpus_setup(char *str) +{ + if (cpulist_parse(str, &wq_cmdline_cpumask) < 0) { + cpumask_clear(&wq_cmdline_cpumask); + pr_warn("workqueue.unbound_cpus: incorrect CPU range, using default\n"); + } + + return 1; +} +__setup("workqueue.unbound_cpus=3D", workqueue_unbound_cpus_setup); --=20 2.17.1