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 89B79C433F5 for ; Wed, 10 Nov 2021 12:59:07 +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 5164E6103C for ; Wed, 10 Nov 2021 12:59:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 5164E6103C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de 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=pbhXMzma7yH8YOcVaHZkAGcmPrAOtY5d5QHcK5iXL9Y=; b=0mzN4XH39Rl59Bg0RRjAOjdESL Fpvv0V9J8MhMNgZQi4edAYSZv0wKAL/rljZeRDRB03p0a8lMdFj9OSVpdd8u2nafrA8I6qi4lTsCP UmNaA/nAKXrw3/wJcbhoRWEBncB8/kUjX0SPsFLq0gppgNpbcAVPQfKA+XEn2zEnVf60OYFy3CgOH wH2EGz8qmOZOWehN7DQopkxgPFm0xCCiSuIN0YG1vPuoHgap72DsBsdS6lAD/Dj59P5uHdcLT0PWU 2qKVTPHVvAKyMZIlnY8yvNdhWc2e5rSlxDFXtF4kiTXPzUMZZBwoKIlU9ZcdXLJOnuoTRXhUZ6sdG 5wF77yQg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mknBv-005UjZ-0t; Wed, 10 Nov 2021 12:59:03 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mknBs-005UiO-Cy for linux-nvme@lists.infradead.org; Wed, 10 Nov 2021 12:59:02 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 2872768AA6; Wed, 10 Nov 2021 13:58:57 +0100 (CET) Date: Wed, 10 Nov 2021 13:58:56 +0100 From: Christoph Hellwig To: Ming Lei Cc: Christoph Hellwig , 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: <20211110125856.GA25614@lst.de> References: <20211110091407.GA8396@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211110_045900_609110_E0B77015 X-CRM114-Status: GOOD ( 20.51 ) 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. Yeah, but why do we need to still call quiesce after we just did a freeze, which is about half of the users?