From nobody Fri Jan 2 15:27:10 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 9ECFBCD8C8E for ; Tue, 10 Oct 2023 14:23:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232939AbjJJOXl (ORCPT ); Tue, 10 Oct 2023 10:23:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58982 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232779AbjJJOXj (ORCPT ); Tue, 10 Oct 2023 10:23:39 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3A59AA4 for ; Tue, 10 Oct 2023 07:23:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1696947779; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=eanIYdQ/OkURqG898KbJm4DzgfTGcpyCx3WajorKeyU=; b=ORX6NROuSgHwmZjSU8b+hPZRR+qzVjRxUG+JqldAIwEC2a0ssG1XL3Dmjyu/Q2qoRpjSgm vHDqm5y/PEa9IvEqh8/Wu/Ab2W5FTykt7feSIpGlzyITi9/XqdGSw6mLR+1AmJi/uqfMVA 9BG14HGkkWuPZAfutUFpMrz1Ap9aOeU= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-101-Ztn_c7GENNWS0tBFcB0GLA-1; Tue, 10 Oct 2023 10:22:51 -0400 X-MC-Unique: Ztn_c7GENNWS0tBFcB0GLA-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id D87EC1C068DC; Tue, 10 Oct 2023 14:22:34 +0000 (UTC) Received: from localhost (unknown [10.72.120.3]) by smtp.corp.redhat.com (Postfix) with ESMTP id 034B125C3; Tue, 10 Oct 2023 14:22:33 +0000 (UTC) From: Ming Lei To: Jens Axboe Cc: linux-block@vger.kernel.org, Tejun Heo , linux-kernel@vger.kernel.org, Ming Lei , Juri Lelli , Andrew Theurer , Joe Mario , Sebastian Jug Subject: [PATCH] blk-mq: add module parameter to not run block kworker on isolated CPUs Date: Tue, 10 Oct 2023 22:22:16 +0800 Message-ID: <20231010142216.1114752-1-ming.lei@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Kernel parameter of `isolcpus=3D` is used for isolating CPUs for specific task, and user often won't want block IO to disturb these CPUs, also long IO latency may be caused if blk-mq kworker is scheduled on these isolated CPUs. Kernel workqueue only respects this limit for WQ_UNBOUND, for bound wq, the responsibility should be on wq user. Add one block layer parameter for not running block kworker on isolated CPUs. Cc: Juri Lelli Cc: Andrew Theurer Cc: Joe Mario Cc: Sebastian Jug Signed-off-by: Ming Lei --- block/blk-mq.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/block/blk-mq.c b/block/blk-mq.c index ec922c6bccbe..c53b5b522053 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -29,6 +29,7 @@ #include #include #include +#include =20 #include =20 @@ -42,6 +43,13 @@ #include "blk-rq-qos.h" #include "blk-ioprio.h" =20 +static bool respect_cpu_isolation; +module_param(respect_cpu_isolation, bool, 0444); +MODULE_PARM_DESC(respect_cpu_isolation, + "Don't schedule blk-mq worker on isolated CPUs passed in " + "isolcpus=3D or nohz_full=3D. User need to guarantee to not run " + "block IO on isolated CPUs (default: false)"); + static DEFINE_PER_CPU(struct llist_head, blk_cpu_done); static DEFINE_PER_CPU(call_single_data_t, blk_cpu_csd); =20 @@ -3926,6 +3934,13 @@ static void blk_mq_map_swqueue(struct request_queue = *q) */ sbitmap_resize(&hctx->ctx_map, hctx->nr_ctx); =20 + if (respect_cpu_isolation) { + cpumask_and(hctx->cpumask, hctx->cpumask, + housekeeping_cpumask(HK_TYPE_DOMAIN)); + cpumask_and(hctx->cpumask, hctx->cpumask, + housekeeping_cpumask(HK_TYPE_WQ)); + } + /* * Initialize batch roundrobin counts */ --=20 2.41.0