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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 8A669C8303C for ; Mon, 7 Jul 2025 08:28:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=OalrTZVgCTcY8CfgCXR2MxPAgz7dMXIrKso6Jipbb5U=; b=LMIexvuxtwJ6YRY83mCiO88hUx Gv9+YiKiSyKG7xN5aUjT2Vcwnrmo27XrU+9ZANgzZuAAq/PCJm1SWrgwZIc/k2wYIGqGJFZ/JwP9f DIt0LtHGL47yr6MRpgsdxNPKi1F0hexYvnSZDqtMnUikkQN9H57EjPOnjmzNUV5En14HCAn1guFsb crtR4al4X8Sw3jW937Q6kgiGUnVVmvXy71BhWofTfyCaA9g+gNunff3S1eP7SBP9b4t9B/K2Ubyr0 2VW5nYMwf0nUUmzqXIQjq0cGjA77/RR8eUoDY9kcVIXTmX9JJ14azGISDQpp0QHWwDtmrtVzmFY7d JWuJA00w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uYhCq-00000001r0b-0W2k; Mon, 07 Jul 2025 08:28:08 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uYgX8-00000001jUJ-1Usu for linux-nvme@lists.infradead.org; Mon, 07 Jul 2025 07:45:03 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1751874300; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=OalrTZVgCTcY8CfgCXR2MxPAgz7dMXIrKso6Jipbb5U=; b=ErtZasqvYfuKgCY0OZ2yYbYDCPtM3TFfJLWOmV96kIsHKaku5w5huvPcpiYoLdGVZKLo32 sB4TEDl0IH98ex/ZJ+gklgG6J7aWDK7uz/ZYytBcdU9SKyJnXtr8HTgsAVkuSC+8jTqlVL FzNC8RzSUkteDJ7jpKQq/+S0t50Z+R4= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-282-ZccoFHbxPKqYGcrylrjfjg-1; Mon, 07 Jul 2025 03:44:54 -0400 X-MC-Unique: ZccoFHbxPKqYGcrylrjfjg-1 X-Mimecast-MFC-AGG-ID: ZccoFHbxPKqYGcrylrjfjg_1751874292 Received: from mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.15]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 60B6F1801211; Mon, 7 Jul 2025 07:44:50 +0000 (UTC) Received: from fedora (unknown [10.72.116.160]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 0525F1956087; Mon, 7 Jul 2025 07:44:35 +0000 (UTC) Date: Mon, 7 Jul 2025 15:44:30 +0800 From: Ming Lei To: Daniel Wagner Cc: Jens Axboe , Keith Busch , Christoph Hellwig , Sagi Grimberg , "Michael S. Tsirkin" , Aaron Tomlin , "Martin K. Petersen" , Thomas Gleixner , Costa Shulyupin , Juri Lelli , Valentin Schneider , Waiman Long , Frederic Weisbecker , Mel Gorman , Hannes Reinecke , Mathieu Desnoyers , linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, megaraidlinux.pdl@broadcom.com, linux-scsi@vger.kernel.org, storagedev@microchip.com, virtualization@lists.linux.dev, GR-QLogic-Storage-Upstream@marvell.com Subject: Re: [PATCH v7 09/10] blk-mq: prevent offlining hk CPUs with associated online isolated CPUs Message-ID: References: <20250702-isolcpus-io-queues-v7-0-557aa7eacce4@kernel.org> <20250702-isolcpus-io-queues-v7-9-557aa7eacce4@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250702-isolcpus-io-queues-v7-9-557aa7eacce4@kernel.org> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250707_004502_467801_9F76B5A1 X-CRM114-Status: GOOD ( 13.31 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Wed, Jul 02, 2025 at 06:33:59PM +0200, Daniel Wagner wrote: > When isolcpus=io_queue is enabled, and the last housekeeping CPU for a > given hctx goes offline, there would be no CPU left to handle I/O. To > prevent I/O stalls, prevent offlining housekeeping CPUs that are still > serving isolated CPUs. > > When isolcpus=io_queue is enabled and the last housekeeping CPU > for a given hctx goes offline, no CPU would be left to handle I/O. > To prevent I/O stalls, disallow offlining housekeeping CPUs that are > still serving isolated CPUs. If you do so, cpu offline is failed, and this change is user visible, please document the cpu offline failure limit on Documentation/admin-guide/kernel-parameters.txt. in the next patch. Thanks, Ming