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=-1.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, T_DKIMWL_WL_HIGH autolearn=ham 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 C8D06C4321D for ; Tue, 21 Aug 2018 07:17:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7524921581 for ; Tue, 21 Aug 2018 07:17:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="j8WXgwZI" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7524921581 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 S1726777AbeHUKgy (ORCPT ); Tue, 21 Aug 2018 06:36:54 -0400 Received: from userp2120.oracle.com ([156.151.31.85]:47560 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726253AbeHUKgx (ORCPT ); Tue, 21 Aug 2018 06:36:53 -0400 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 w7L7EI3x060279; Tue, 21 Aug 2018 07:17:52 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=t/TthygHuB5vcQaBCdvDGh7YmGWB1WHjRAhPrMG/A/s=; b=j8WXgwZIqgv5Le5FaNNTHl77QCyfeY4hEHlSg89lWYec72vjAd7M912xHvQqlYkv2FSO CU3JkI5xmdI0Ec/vrrLV1a5QrXXEDBqxtwIqIdOgjpKtRnctJ4FRZeN1lFrZiQhkG99U Msps73FEmoGYO6e/UGxTeUIE4DzoeO2Ctxl3ELLJr8qciq/8rnziIM2hkYtv11PnGsvt d59TNSOb19NlYbhYIGYNeBDj1DP7JMwIDw0wz9VAeKuv9kcIHDatKhaboPixlnZygjyI cupxov8pZw8QlVvMfPwdKYuJkKWZQVXOhxhp6ejumQyY5RhiUqL+G2qLN2tA5OjzcYYc hA== Received: from userv0021.oracle.com (userv0021.oracle.com [156.151.31.71]) by userp2120.oracle.com with ESMTP id 2kxc3qjgbt-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 21 Aug 2018 07:17:52 +0000 Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by userv0021.oracle.com (8.14.4/8.14.4) with ESMTP id w7L7HpnD006634 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 21 Aug 2018 07:17:52 GMT Received: from abhmp0008.oracle.com (abhmp0008.oracle.com [141.146.116.14]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id w7L7Hpf9023881; Tue, 21 Aug 2018 07:17:51 GMT Received: from [10.182.69.179] (/10.182.69.179) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Tue, 21 Aug 2018 00:17:51 -0700 Subject: Re: [PATCH V3 1/2] blk-mq: init hctx sched after update ctx and hctx mapping To: Jens Axboe Cc: tom.leiming@gmail.com, bart.vanassche@wdc.com, keith.busch@linux.intel.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org References: <1534749606-7311-1-git-send-email-jianchao.w.wang@oracle.com> <1534749606-7311-2-git-send-email-jianchao.w.wang@oracle.com> <048cdf08-6c9e-f54a-1e5c-f1d40fb2ecdb@kernel.dk> From: "jianchao.wang" Message-ID: Date: Tue, 21 Aug 2018 15:18:24 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <048cdf08-6c9e-f54a-1e5c-f1d40fb2ecdb@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=8991 signatures=668707 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1807170000 definitions=main-1808210077 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Jens On 08/20/2018 10:45 PM, Jens Axboe wrote: > On 8/20/18 1:20 AM, Jianchao Wang wrote: >> @@ -2913,6 +2906,29 @@ static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, >> list_for_each_entry(q, &set->tag_list, tag_set_list) >> blk_mq_freeze_queue(q); >> >> + /* >> + * switch io scheduler to NULL to clean up the data in it. >> + * will get it back after update mapping between cpu and hw queues. >> + */ > > "Switch IO scheduler to 'none', cleaning up the data associated with > the previous scheduler. We'll switch back once we're done updating > the new sw to hw queue mappings. > >> + list_for_each_entry(q, &set->tag_list, tag_set_list) { >> + if (!q->elevator) { >> + q->elv_type = NULL; >> + continue; >> + } >> + q->elv_type = q->elevator->type; >> + mutex_lock(&q->sysfs_lock); >> + /* >> + * After elevator_switch_mq, the previous elevator_queue will be >> + * released by elevator_release. The reference of the io scheduler >> + * module get by elevator_get will also be put. So we need to get >> + * a reference of the io scheduler module here to prevent it to be >> + * removed. >> + */ >> + __module_get(q->elv_type->elevator_owner); >> + elevator_switch_mq(q, NULL); >> + mutex_unlock(&q->sysfs_lock); >> + } > > I don't hate this, but I also find it pretty annoying to put local state > into the queue itself. It would be much nicer _not_ to have ->elv_type > in the queue itself. That would need an allocation, however... > > Apart from those two things, looks fine to me. > Thanks very much for your comment. I have reworked this patch based on your kindly suggestion and posted the V4. Thanks Jianchao