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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EFD27C433EF for ; Fri, 8 Jul 2022 08:04:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237602AbiGHIEr (ORCPT ); Fri, 8 Jul 2022 04:04:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39938 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237530AbiGHIEq (ORCPT ); Fri, 8 Jul 2022 04:04:46 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:3::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A2F988048A; Fri, 8 Jul 2022 01:04:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=Rmp5G6vHPz8jBiOD5JA28ORVQFrjzvX/1JW4d9qp04s=; b=LAlSn1iqreBWIix6My/aDS6Q/L HR4U2riupSczgF0sIB8Q8jo7HKYnDmfAo0lHO+kiuXXNdjsVmaKykHg/akDHYJaXQ1oUPjXbV//3T phwsavr1Ko39mwTfHhQ8a1ZBLs++x77pebkPj/qPsVSWz8wYEWV3+1nKbsJSnOfgLJOG9Fwqivf1e ALxw5RK7DfKDEKZj/vdx7SWT5pgyzF4qXxjtjTw12dK6OyPMRClSifdf5i5L1b9SSH36zvGT7I0sJ 56Urr9rBTo+UpLk8LmgltvF2qQt1SjdYcIvc2206PjLP47kpdTavNbal65G8081FrtnFAe5OTUmWx lWhIcBrw==; Received: from hch by bombadil.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1o9iyi-002MH3-AR; Fri, 08 Jul 2022 08:04:44 +0000 Date: Fri, 8 Jul 2022 01:04:44 -0700 From: Christoph Hellwig To: Sergei Shtepa Cc: Christoph Hellwig , "axboe@kernel.dk" , "linux-block@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 15/20] block, blksnap: snapshot image block device Message-ID: References: <1655135593-1900-1-git-send-email-sergei.shtepa@veeam.com> <1655135593-1900-16-git-send-email-sergei.shtepa@veeam.com> <49039d2b-e4bc-62a1-7b4a-a78001a2f430@veeam.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Fri, Jul 08, 2022 at 09:58:25AM +0200, Sergei Shtepa wrote: > There was a goal to use the kernel innovations whenever possible. > Of course, it makes sense to return to bio based if it allows to > achieve better performance. This is not a matter of principle. In general blk-mq is designed for hardware drivers, while the bio based interface is for stacking drivers. There are some exceptions: dm-mpath is a stacking blk-mq driver, but one that just passes I/O through, and there is a bunch of hardware drivers implemented as bio based ones, although I suspect most of them would end up being improved by switching to blk-mq (or in most case by just deleting them).