From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932211AbbKLQAt (ORCPT ); Thu, 12 Nov 2015 11:00:49 -0500 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:36570 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932070AbbKLQAs (ORCPT ); Thu, 12 Nov 2015 11:00:48 -0500 Subject: Re: [PATCH] null_blk: Register as a LightNVM device To: Christoph Hellwig References: <1447236398-9421-1-git-send-email-m@bjorling.me> <20151112085327.GA28149@infradead.org> <5644B4F4.5090805@kernel.dk> <20151112155230.GA30642@infradead.org> <5644B648.6060500@fb.com> <20151112155831.GA9562@infradead.org> CC: Jens Axboe , Matias Bj??rling , , From: Jens Axboe Message-ID: <5644B794.6070509@fb.com> Date: Thu, 12 Nov 2015 09:00:20 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <20151112155831.GA9562@infradead.org> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [192.168.54.13] X-Proofpoint-Spam-Reason: safe X-FB-Internal: Safe X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2015-11-12_08:,, signatures=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/12/2015 08:58 AM, Christoph Hellwig wrote: > On Thu, Nov 12, 2015 at 08:54:48AM -0700, Jens Axboe wrote: >>> 300 lines of boilerplate for just setting up a few request_queues seem >>> wrong, can you show the actual patch you measured? >> >> I just took it from Matias' last posting: >> >> http://marc.info/?l=linux-kernel&m=144605858228534&w=2 > > Well, that one has all these crazy completion methods which > are of no use for a blk-mq driver, so it should really be > compared without those. So we can cut it down a bit, it's still going to be the same boilerplate code that null_blk has, even with just mq completions. If it ended up rewriting null_blk to be something else entirely or full of ifdef sprinkles, I'd agree. But for adding a hundred lines of code to be able to test lightnvm perf, I think it's a no-brainer to just add it to null_blk and not have a separate module. -- Jens Axboe