From nobody Sun Feb 8 13:10:54 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 04AA8EB64DD for ; Wed, 28 Jun 2023 11:19:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231698AbjF1LTG (ORCPT ); Wed, 28 Jun 2023 07:19:06 -0400 Received: from mx5.didiglobal.com ([111.202.70.122]:48772 "HELO mx5.didiglobal.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S230498AbjF1LSq (ORCPT ); Wed, 28 Jun 2023 07:18:46 -0400 Received: from mail.didiglobal.com (unknown [10.79.65.12]) by mx5.didiglobal.com (Maildata Gateway V2.8) with ESMTPS id 59374B002422E; Wed, 28 Jun 2023 19:18:42 +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; Wed, 28 Jun 2023 19:18:41 +0800 Date: Wed, 28 Jun 2023 19:18:34 +0800 X-MD-Sfrom: tiozhang@didiglobal.com X-MD-SrcIP: 10.79.65.12 From: tiozhang To: CC: , , , , , , , , Subject: [PATCH v4] workqueue: add cmdline parameter `workqueue.unbound_cpus` to further constrain wq_unbound_cpumask at boot time Message-ID: <20230628111722.GA31661@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@didiglobal.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 --- .../admin-guide/kernel-parameters.txt | 7 +++++++ kernel/workqueue.c | 20 +++++++++++++++++++ 2 files changed, 27 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..29e8254edd63 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 +6135,17 @@ 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) +{ + int ret; + + ret =3D cpulist_parse(str, &wq_cmdline_cpumask); + if (ret < 0) { + cpumask_clear(&wq_cmdline_cpumask); + pr_warn("workqueue.unbound_cpus: incorrect CPU range\n"); + } + + return ret; +} +__setup("workqueue.unbound_cpus=3D", workqueue_unbound_cpus_setup); --=20 2.17.1