Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754555Ab3JVSzo (ORCPT ); Tue, 22 Oct 2013 14:55:44 -0400 Received: from mail-lb0-f170.google.com ([209.85.217.170]:64217 "EHLO mail-lb0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753995Ab3JVSzn (ORCPT ); Tue, 22 Oct 2013 14:55:43 -0400 Message-ID: <5266CA29.2020308@bjorling.me> Date: Tue, 22 Oct 2013 20:55:37 +0200 From: Matias Bjorling User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.0.1 MIME-Version: 1.0 To: Keith Busch , axboe@kernel.dk CC: willy@linux.intel.com, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org Subject: Re: [PATCH 3/3] NVMe: Convert to blk-mq References: <1382102062-22270-1-git-send-email-m@bjorling.me> <1382102062-22270-4-git-send-email-m@bjorling.me> <526186AE.3080006@bjorling.me> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2252 Lines: 54 Den 22-10-2013 18:55, Keith Busch skrev: > On Fri, 18 Oct 2013, Matias Bj?rling wrote: >> On 10/18/2013 05:13 PM, Keith Busch wrote: >>> On Fri, 18 Oct 2013, Matias Bjorling wrote: >>>> The nvme driver implements itself as a bio-based driver. This >>>> primarily >>>> because of high lock congestion for high-performance nvm devices. To >>>> remove the congestion within the traditional block layer, a >>>> multi-queue >>>> block layer is being implemented. > >>>> - result = nvme_map_bio(nvmeq, iod, bio, dma_dir, psegs); >>>> - if (result <= 0) >>>> + if (nvme_map_rq(nvmeq, iod, rq, dma_dir)) >>>> goto free_cmdid; >>>> - length = result; >>>> >>>> - cmnd->rw.command_id = cmdid; >>>> + length = blk_rq_bytes(rq); >>>> + >>>> + cmnd->rw.command_id = rq->tag; >>> >>> The command ids have to be unique on a submission queue. Since each >>> namespace's blk-mq has its own 'tags' used as command ids here but >>> share >>> submission queues, what's stopping the tags for commands sent to >>> namespace >>> 1 from clashing with tags for namespace 2? >>> >>> I think this would work better if one blk-mq was created per device >>> rather than namespace. It would fix the tag problem above and save a >>> lot of memory potentially wasted on millions of requests allocated that >>> can't be used. >> >> You're right. I didn't see the connection. In v3 I'll push struct >> request_queue to nvme_dev and map the queues appropriately. It will >> also fix the command id issues. > > Just anticipating a possible issue with the suggestion. Will this > separate > the logical block size from the request_queue? Each namespace can have > a different format, so the block size and request_queue can't be tied > together like it currently is for this to work. If only a couple of different logical sizes are to be expected (1-4), we can keep a list of already initialized request queues, and use the one that match an already initialized? Axboe, do you know of a better solution? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/