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 X-Spam-Level: X-Spam-Status: No, score=-6.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 63BD5C11F65 for ; Wed, 30 Jun 2021 08:48:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4E92861CD4 for ; Wed, 30 Jun 2021 08:48:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233934AbhF3Iub (ORCPT ); Wed, 30 Jun 2021 04:50:31 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:30506 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233875AbhF3Iu2 (ORCPT ); Wed, 30 Jun 2021 04:50:28 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1625042879; 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=3BRgUmAkhzxR66VtSPc5n97wSxRw2/ltCg6mBskAIrE=; b=GzuJ1bJhu3XXN9WRoS9LE5QaQ4vYNg6xVTINiehiKiTA8ZOY+erVyXmSckmuclAvJokBOx 5+Ppu/Bs+U0oB7ntJWOJYLyhThqYNO327GwdKT1dYjxqLNCfVT5S2Wjzu3OShCdrvs5CBr Fy3w1kftNhqZ89SbWylDhPF29JViU4Q= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-243-dcquosp0M5yTB3x8-TK3gg-1; Wed, 30 Jun 2021 04:47:58 -0400 X-MC-Unique: dcquosp0M5yTB3x8-TK3gg-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 33816A40C1; Wed, 30 Jun 2021 08:47:56 +0000 (UTC) Received: from T590 (ovpn-13-153.pek2.redhat.com [10.72.13.153]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B2EC25C230; Wed, 30 Jun 2021 08:47:48 +0000 (UTC) Date: Wed, 30 Jun 2021 16:47:44 +0800 From: Ming Lei To: Hannes Reinecke Cc: Jens Axboe , linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, Christoph Hellwig , Sagi Grimberg , Daniel Wagner , Wen Xiong , John Garry Subject: Re: [PATCH 2/2] nvme: pass BLK_MQ_F_NOT_USE_MANAGED_IRQ for fc/rdma/tcp/loop Message-ID: References: <20210629074951.1981284-1-ming.lei@redhat.com> <20210629074951.1981284-3-ming.lei@redhat.com> <46fdb02d-8d71-d465-072d-5e8d6ec3601f@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <46fdb02d-8d71-d465-072d-5e8d6ec3601f@suse.de> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Wed, Jun 30, 2021 at 10:15:46AM +0200, Hannes Reinecke wrote: > On 6/29/21 9:49 AM, Ming Lei wrote: > > All the 4 host drivers don't use managed irq for completing request, so > > it is correct to pass the flag to blk-mq. > > > > Secondly with this flag, blk-mq will help us dispatch connect request > > allocated via blk_mq_alloc_request_hctx() to driver even though all > > CPU in the specified hctx's cpumask are offline. > > > How is this supposed to work? > To my understanding, only cpus in the hctx cpumask are eligible to send I/O. > So if all of these CPUs are offline, who exactly is submitting I/O? > More to the point, which CPU will be submitting the connect request? Please see __blk_mq_delay_run_hw_queue(), which will pass WORK_CPU_UNBOUND to kblockd_mod_delayed_work_on() for this situation. Thanks, Ming