From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3B61B133987 for ; Sat, 11 Jan 2025 03:41:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736566873; cv=none; b=AiBxcZccJcLBXRHYIFAGlqyB3SDRbr3IVBeHhvLTsiDadVl08thM9sPv1BVnF7ZBHSn29ECaaOnSX6v7Lk/MJHA7M84DQi+x6j44pe6wzjeUC+YrqN4sR1AD2Qr6PRYGYElGcaEGUzyZMKlRXAPbPKANSNpY9TYXOtGK6GevHi4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736566873; c=relaxed/simple; bh=SY3ZkHRd1kXRdXW/z27Av3VBVXcUG9mklyUNsdIljHk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Pz3eE308Y0Dhko3dUnLMzIoOZft7xxBwJxw1GObTtul9oE2zJ0BFG4rCiXsFkIHR5JnBYAlNpdtH8rb0p3YFA6L2ajhhlpas4KkBqvt1C7dVvOj7qjhezxa3EAI1VQzQG39xioLPHCvYzI0z6Sj2/j/FOpw+LoHi+xAdkeHIjxc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=JDe/n3NY; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="JDe/n3NY" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1736566871; 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=gFwpZ4lNqHc8a93lKvyOmLFaFeR0q5NU2Y4FGP31Aws=; b=JDe/n3NY1qj0j1ZtrXNrtKHxWbD4dvDBKoIrfg9khYFLEDSX1ylEQjxsB3MzwZcNqalEfl 5WV+Yo8vVAROzqAogr5rmBViWoPoHunOfaycsAAMNFlQCDjfMyzFr9R8vH0LBndEjJMKfZ DiCL2kI3FRXy91MFmQ48cEzMkz0xHqM= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-284-9L9FZIIhP4Sk_aSRXlxo0Q-1; Fri, 10 Jan 2025 22:41:05 -0500 X-MC-Unique: 9L9FZIIhP4Sk_aSRXlxo0Q-1 X-Mimecast-MFC-AGG-ID: 9L9FZIIhP4Sk_aSRXlxo0Q Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (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-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 3FD781956083; Sat, 11 Jan 2025 03:40:58 +0000 (UTC) Received: from fedora (unknown [10.72.116.10]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id EFABD19560AB; Sat, 11 Jan 2025 03:40:44 +0000 (UTC) Date: Sat, 11 Jan 2025 11:40:39 +0800 From: Ming Lei To: Daniel Wagner Cc: Jens Axboe , Keith Busch , Christoph Hellwig , Sagi Grimberg , "Michael S. Tsirkin" , "Martin K. Petersen" , Thomas Gleixner , Costa Shulyupin , Juri Lelli , Valentin Schneider , Waiman Long , Frederic Weisbecker , Mel Gorman , Hannes Reinecke , 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 v5 8/9] blk-mq: issue warning when offlining hctx with online isolcpus Message-ID: References: <20250110-isolcpus-io-queues-v5-0-0e4f118680b0@kernel.org> <20250110-isolcpus-io-queues-v5-8-0e4f118680b0@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250110-isolcpus-io-queues-v5-8-0e4f118680b0@kernel.org> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Hi Daniel, On Fri, Jan 10, 2025 at 05:26:46PM +0100, Daniel Wagner wrote: > When isolcpus=managed_irq is enabled, and the last housekeeping CPU for > a given hardware context goes offline, there is no CPU left which > handles the IOs anymore. If isolated CPUs mapped to this hardware > context are online and an application running on these isolated CPUs > issue an IO this will lead to stalls. > > The kernel will not schedule IO to isolated CPUS thus this avoids IO > stalls. > > Thus issue a warning when housekeeping CPUs are offlined for a hardware > context while there are still isolated CPUs online. Why do you continue to send patch without addressing the fundamental regression? This patchset does break existed applications which can't follow the new rule of offlining CPU in order. Again, it violates no-regression rule of kernel development. Thanks, Ming