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 X-Spam-Level: X-Spam-Status: No, score=-2.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 677BAC65BAF for ; Fri, 7 Dec 2018 03:46:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 20A1220837 for ; Fri, 7 Dec 2018 03:46:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="wb00NC2S" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 20A1220837 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=oracle.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726072AbeLGDqI (ORCPT ); Thu, 6 Dec 2018 22:46:08 -0500 Received: from userp2120.oracle.com ([156.151.31.85]:35310 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725985AbeLGDqH (ORCPT ); Thu, 6 Dec 2018 22:46:07 -0500 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.22/8.16.0.22) with SMTP id wB73iB1c011426; Fri, 7 Dec 2018 03:46:04 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : to : cc : references : from : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=corp-2018-07-02; bh=uoNKBL0sDI8g3iXoG6H5+iI4UHsf5aH/TjM8wiLHXeI=; b=wb00NC2SbCm+41MrjeZNfKDdn08wiYgz2aT8VaSj3N6Z3gGKWbdJkoVM6WH7oTbTQhQ/ 0aaVMYzR+Y0ogl/6lzrMzS1sJ5GhyxpR0NHwj8WdqYVEYr7awV2AAB39HdAzLKsVWH/b zlF4kD9l7PwCGgzAODGuMp7LVECp7sTozX9DGsqLhd8hfbaBgPl1FLnS3WydIwbO6S9X Opw6cf6OIKtJEBdSn7Rj6njlFiY+AHxJsAOJE4uQfyQ8CNtii4qu6GjBi/2Qa+xidoCD 1OH7yAmuWM1LrbfC+wqfmElhQ88Z1gkRLVeWSn3Nig4KJ02ms37Iw1GYExW0i8eopyTK zA== Received: from aserv0022.oracle.com (aserv0022.oracle.com [141.146.126.234]) by userp2120.oracle.com with ESMTP id 2p3jxrujm9-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 07 Dec 2018 03:46:03 +0000 Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by aserv0022.oracle.com (8.14.4/8.14.4) with ESMTP id wB73k1cj018806 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 7 Dec 2018 03:46:02 GMT Received: from abhmp0007.oracle.com (abhmp0007.oracle.com [141.146.116.13]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id wB73k1hC014239; Fri, 7 Dec 2018 03:46:01 GMT Received: from [10.182.69.118] (/10.182.69.118) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 06 Dec 2018 19:46:01 -0800 Subject: Re: [PATCH V11 0/4] blk-mq: refactor code of issue directly To: Jens Axboe Cc: ming.lei@redhat.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org References: <1544152185-32667-1-git-send-email-jianchao.w.wang@oracle.com> <0adf3419-bcce-93d8-51fb-aee7cbb5ae17@oracle.com> <16205e68-aa5e-c59d-364e-4164a0e51dc7@kernel.dk> <1e183b77-2c4d-71ff-b019-2b1070d2ed6b@kernel.dk> From: "jianchao.wang" Message-ID: <38eb7c50-dfad-d9cb-f8ab-a8f5250b0ed7@oracle.com> Date: Fri, 7 Dec 2018 11:46:43 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <1e183b77-2c4d-71ff-b019-2b1070d2ed6b@kernel.dk> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9099 signatures=668679 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=952 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1812070030 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/7/18 11:42 AM, Jens Axboe wrote: > On 12/6/18 8:41 PM, jianchao.wang wrote: >> >> >> On 12/7/18 11:34 AM, Jens Axboe wrote: >>> On 12/6/18 8:32 PM, Jens Axboe wrote: >>>> On 12/6/18 8:26 PM, jianchao.wang wrote: >>>>> >>>>> >>>>> On 12/7/18 11:16 AM, Jens Axboe wrote: >>>>>> On 12/6/18 8:09 PM, Jianchao Wang wrote: >>>>>>> Hi Jens >>>>>>> >>>>>>> Please consider this patchset for 4.21. >>>>>>> >>>>>>> It refactors the code of issue request directly to unify the interface >>>>>>> and make the code clearer and more readable. >>>>>>> >>>>>>> This patch set is rebased on the recent for-4.21/block and add the 1st >>>>>>> patch which inserts the non-read-write request to hctx dispatch >>>>>>> list to avoid to involve merge and io scheduler when bypass_insert >>>>>>> is true, otherwise, inserting is ignored, BLK_STS_RESOURCE is returned >>>>>>> and the caller will fail forever. >>>>>>> >>>>>>> The 2nd patch refactors the code of issue request directly to unify the >>>>>>> helper interface which could handle all the cases. >>>>>>> >>>>>>> The 3rd patch make blk_mq_sched_insert_requests issue requests directly >>>>>>> with 'bypass' false, then it needn't to handle the non-issued requests >>>>>>> any more. >>>>>>> >>>>>>> The 4th patch replace and kill the blk_mq_request_issue_directly. >>>>>> >>>>>> Sorry to keep iterating on this, but let's default to inserting to >>>>>> the dispatch list if we ever see busy from a direct dispatch. I'm fine >>>>>> with doing that for 4.21, as suggested by Ming, I just didn't want to >>>>>> fiddle with it for 4.20. This will prevent any merging on the request >>>>>> going forward, which I think is a much safer default. >>>>>> >>>>>> You do this already for some cases. Let's do it unconditionally for >>>>>> a request that was ever subjected to ->queue_rq() and we didn't either >>>>>> error or finish after the fact. >>>>>> >>>>> I have done it in this version if I get your point correctly. >>>>> Please refer to the following fragment in the 2nd patch. >>>>> >>>>> + /* >>>>> + * If the request is issued unsuccessfully with >>>>> + * BLK_STS_DEV_RESOURCE or BLK_STS_RESOURCE, insert >>>>> + * the request to hctx dispatch list due to attached >>>>> + * lldd resource. >>>>> + */ >>>>> + force = true; >>>>> + ret = __blk_mq_issue_directly(hctx, rq, cookie, last); >>>>> +out_unlock: >>>>> + hctx_unlock(hctx, srcu_idx); >>>>> +out: >>>>> + switch (ret) { >>>>> + case BLK_STS_OK: >>>>> + break; >>>>> + case BLK_STS_DEV_RESOURCE: >>>>> + case BLK_STS_RESOURCE: >>>>> + if (force) { >>>>> + blk_mq_request_bypass_insert(rq, run_queue); >>>>> + ret = bypass ? BLK_STS_OK : ret; >>>>> + } else if (!bypass) { >>>>> + blk_mq_sched_insert_request(rq, false, >>>>> + run_queue, false); >>>>> + } >>>>> + break; >>>>> + default: >>>> >>>> You are right, I missed that you set force = true before doing the >>>> issue. So this looks good to me! >>> >>> I applied your series. With this, we should be good to remove the >>> REQ_NOMERGE logic that was added for the corruption case, and the >>> blk_rq_can_direct_dispatch() as well? >>> >> >> Yes, it should be that. >> Every thing rejected by .queue_rq is ended or inserted into hctx dispatch >> list. And also direct-issue path is unified with normal path. > > Why are we doing that return value dance, depending on whether this > is a bypass insert or not? That seems confusing. > For the 'bypass == false' case, it need to know whether the request is issued successfully. This is for the 3rd patch. I used to use the returned cookie to identify the result, but you don't like it. So I have to use this return value. Thanks Jianchao