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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C8C1AC433F5 for ; Wed, 10 Nov 2021 09:52:35 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 99B2D61076 for ; Wed, 10 Nov 2021 09:52:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 99B2D61076 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org 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=7oqI1vSf7oW8hr4gNp34G0zlAlDGH6S3+qYy9C5RByg=; b=QlgzBri0fS1JEH8NZZeOMEnM7U xlTx6jtZAP+nHn1/8B/5MTd1wFZOaXPULQRjaFRNwWqQUJc+XZ9ueV6AbPWw3I0IRO5TRRikL9kgh bMdjeXAYb9G+r/pGPhFmNWXN1U2aGgAYh7s4JNjpA7lbrobvqAwnqJ7VER9Rz/nVFg9yPe5Zl9EDN pe037HW8vRDmgNlM7DgXOHwCTBc16HQkDvmyVoj979i0SMEYhI4aIWUlm4U8SbdpVYjCu42hDW+xs OKf6vqWY8NIUF05cZ5vF+Mdme27BTNFLvYfE4+yZS3QAGeNJ7CIolNCHklJu+Ds0OJNcQz+DiEOQz wjNnZ3OA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mkkHO-0051od-Dx; Wed, 10 Nov 2021 09:52:30 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mkkHL-0051nv-G4 for linux-nvme@lists.infradead.org; Wed, 10 Nov 2021 09:52:28 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1636537946; 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=7oqI1vSf7oW8hr4gNp34G0zlAlDGH6S3+qYy9C5RByg=; b=f2jgHEhl3pAW1QX0dOpMf39e9G5VKa6SMehA6t5SHjf3xzlg9SrRntmVxS7z+MPyQFJhtn iHP4pZYaL9DtidvEdwsy8NMbYtjy9DQISigNawtQmXo6YnOJun4b94LiUNDSl9CBJJeE/x SgVn2LhxsQCkSTTEXlH34ZzrIf3RdIQ= 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-208-pCtNLx6KN3WaiDesogfB7w-1; Wed, 10 Nov 2021 04:52:25 -0500 X-MC-Unique: pCtNLx6KN3WaiDesogfB7w-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 07A50804141; Wed, 10 Nov 2021 09:52:24 +0000 (UTC) Received: from T590 (ovpn-8-19.pek2.redhat.com [10.72.8.19]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 118E410016F2; Wed, 10 Nov 2021 09:52:20 +0000 (UTC) Date: Wed, 10 Nov 2021 17:52:13 +0800 From: Ming Lei To: Christoph Hellwig Cc: Jens Axboe , linux-block@vger.kernel.org, linux-scsi@vger.kernel.org, linux-nvme@lists.infradead.org Subject: Re: sorting out the freeze / quiesce mess Message-ID: References: <20211110091407.GA8396@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211110_015227_636134_C96172DB X-CRM114-Status: GOOD ( 18.11 ) 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, Nov 10, 2021 at 05:29:26PM +0800, Ming Lei wrote: > On Wed, Nov 10, 2021 at 10:14:07AM +0100, Christoph Hellwig wrote: > > Hi Jens and Ming, > > > > I've been looking into properly supporting queue freezing for bio based > > drivers (that is only release q_usage_counter on bio completion for them). > > And the deeper I look into the code the more I'm confused by us having > > the blk_mq_quiesce* interface in addition to blk_freeze_queue. What > > is a good reason to do a quiesce separately from a freeze? > > freeze can make sure that all requests are done, quiesce can make sure that > dispatch critical area(covered by hctx lock/unlock) is done. Another difference: quiesce usually is used to stop to queue requests to LLD, and driver needs no requets queued any more after the interface returns, freeze can't do that. Thanks, Ming