Return-Path: Received: from mail-pl1-f194.google.com ([209.85.214.194]:46812 "EHLO mail-pl1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725939AbeKUPOz (ORCPT ); Wed, 21 Nov 2018 10:14:55 -0500 Subject: Re: [PATCH V10 09/19] block: introduce bio_bvecs() From: Sagi Grimberg To: Ming Lei Cc: Christoph Hellwig , Jens Axboe , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Dave Chinner , Kent Overstreet , Mike Snitzer , dm-devel@redhat.com, Alexander Viro , linux-fsdevel@vger.kernel.org, Shaohua Li , linux-raid@vger.kernel.org, linux-erofs@lists.ozlabs.org, David Sterba , linux-btrfs@vger.kernel.org, "Darrick J . Wong" , linux-xfs@vger.kernel.org, Gao Xiang , Theodore Ts'o , linux-ext4@vger.kernel.org, Coly Li , linux-bcache@vger.kernel.org, Boaz Harrosh , Bob Peterson , cluster-devel@redhat.com References: <20181115085306.9910-1-ming.lei@redhat.com> <20181115085306.9910-10-ming.lei@redhat.com> <20181116134541.GH3165@lst.de> <002fe56b-25e4-573e-c09b-bb12c3e8d25a@grimberg.me> <20181120161651.GB2629@lst.de> <53526aae-fb9b-ee38-0a01-e5899e2d4e4d@grimberg.me> <20181121005902.GA31748@ming.t460p> <2d9bee7a-f010-dcf4-1184-094101058584@grimberg.me> <20181121034415.GA8408@ming.t460p> <2a47d336-c19b-6bf4-c247-d7382871eeea@grimberg.me> Message-ID: <7378bf49-5a7e-5622-d4d1-808ba37ce656@grimberg.me> Date: Tue, 20 Nov 2018 20:42:04 -0800 MIME-Version: 1.0 In-Reply-To: <2a47d336-c19b-6bf4-c247-d7382871eeea@grimberg.me> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-ext4-owner@vger.kernel.org List-ID: >> Yeah, that is the most common example, given merge is enabled >> in most of cases. If the driver or device doesn't care merge, >> you can disable it and always get single bio request, then the >> bio's bvec table can be reused for send(). > > Does bvec_iter span bvecs with your patches? I didn't see that change? Wait, I see that the bvec is still a single array per bio. When you said a table I thought you meant a 2-dimentional array... Unless I'm not mistaken, I think that the change is pretty simple then. However, nvme-tcp still needs to be bio aware unless we have some abstraction in place.. Which will mean that nvme-tcp will need to open-code bio_bvecs.