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 766F1C28CF5 for ; Wed, 26 Jan 2022 08:11:06 +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=gEUGLzp3K3Ka5xmeccgBixQP0B4yiVBBrDcf4TfGoGo=; b=uXxSxG77v2RbpAxo8KIc1YkGLw T3UVYwk9NdGoHK3gflkdEZ0Bjmxqs6mwbp7F4GprD7pk4ZgBdn44Ti2UR7uA9TlmfvEyHFw2oaox7 IqZnT9ut0H7KhgVszbDQvzj3sfVWAsPzzBk5Oh3D6fIQOv+JrAB3tdIwn2u6mVLx+C/Dz7ECLg5kO z2owipCmozcm3NO0FDuEqYC682u5wEL/gHOHRr9dPdGp1dtdKcfhuzp1PSxjsMXaxPX1IkdKjPLaN Kup4fQcyYpJn/Po30bnl+XNPBxvprf2nm7BehOHZvrVDVbOx5TgU8fAvs3C0YjWZupv3FzLJ+GTKE ZQ06K0bg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nCdOP-00AdtV-T6; Wed, 26 Jan 2022 08:11:01 +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 1nCdON-00Adro-Im for linux-nvme@lists.infradead.org; Wed, 26 Jan 2022 08:11:00 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id DB70F68AFE; Wed, 26 Jan 2022 09:10:52 +0100 (CET) Date: Wed, 26 Jan 2022 09:10:52 +0100 From: Christoph Hellwig To: Ming Lei Cc: Christoph Hellwig , Jens Axboe , "Martin K . Petersen" , linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, linux-scsi@vger.kernel.org Subject: Re: [PATCH V2 05/13] block: only account passthrough IO from userspace Message-ID: <20220126081052.GA23154@lst.de> References: <20220122111054.1126146-1-ming.lei@redhat.com> <20220122111054.1126146-6-ming.lei@redhat.com> <20220124130555.GD27269@lst.de> <20220125061634.GA26495@lst.de> <20220125071906.GA27674@lst.de> <20220126055003.GA21089@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-20220126_001059_811105_A6FB44EA X-CRM114-Status: GOOD ( 22.53 ) 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, Jan 26, 2022 at 03:21:04PM +0800, Ming Lei wrote: > > I think the right way would be to just remove this branch entirely. > > This means we only account bios with a block_device, which implies > > they have a gendisk. > > That will not account userspace IO, and people may complain. > > We can just account passthrough request from userspace by the patch > in my last email. Let's take a step back: what I/O do we want to account, and how do we want to archive that? Assuming accounting is enabled: - current mainline accounts all I/O one queues that have a gendisk - your original patch accounts file system I/O and some passthrough I/O that has a special flag set Dropping the conditional to grab a bdev from the queue leaves us with the following rule: - all I/O that has a bio and bdev is accounted. This requires passthrough I/O to explicitly set the bdev in case we haven't done so, and it requires them to have a bio at all I guess you are worried about the latter conditionin that we stop accounting for no data transfer passthrough commands?