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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 E14DBC76188 for ; Tue, 16 Jul 2019 06:54:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B70152145D for ; Tue, 16 Jul 2019 06:54:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726420AbfGPGyb (ORCPT ); Tue, 16 Jul 2019 02:54:31 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:2230 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726295AbfGPGya (ORCPT ); Tue, 16 Jul 2019 02:54:30 -0400 Received: from DGGEMS408-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id F125F11D33B56478A3DF; Tue, 16 Jul 2019 14:54:27 +0800 (CST) Received: from [127.0.0.1] (10.74.223.225) by DGGEMS408-HUB.china.huawei.com (10.3.19.208) with Microsoft SMTP Server id 14.3.439.0; Tue, 16 Jul 2019 14:54:26 +0800 Subject: Re: [RFC PATCH 0/7] blk-mq: improvement on handling IO during CPU hotplug To: Ming Lei , Jens Axboe CC: , "James E . J . Bottomley" , "Martin K . Petersen" , , Bart Van Assche , "Hannes Reinecke" , Christoph Hellwig , Thomas Gleixner , Keith Busch References: <20190712024726.1227-1-ming.lei@redhat.com> From: John Garry Message-ID: Date: Tue, 16 Jul 2019 14:54:24 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20190712024726.1227-1-ming.lei@redhat.com> Content-Type: text/plain; charset="gbk"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.74.223.225] X-CFilter-Loop: Reflected Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org ÔÚ 12/07/2019 10:47, Ming Lei дµÀ: > Hi, > > Thomas mentioned: > " > That was the constraint of managed interrupts from the very beginning: > > The driver/subsystem has to quiesce the interrupt line and the associated > queue _before_ it gets shutdown in CPU unplug and not fiddle with it > until it's restarted by the core when the CPU is plugged in again. > " > > But no drivers or blk-mq do that before one hctx becomes dead(all > CPUs for one hctx are offline), and even it is worse, blk-mq stills tries > to run hw queue after hctx is dead, see blk_mq_hctx_notify_dead(). > > This patchset tries to address the issue by two stages: > > 1) add one new cpuhp state of CPUHP_AP_BLK_MQ_ONLINE > > - mark the hctx as internal stopped, and drain all in-flight requests > if the hctx is going to be dead. > > 2) re-submit IO in the state of CPUHP_BLK_MQ_DEAD after the hctx becomes dead > > - steal bios from the request, and resubmit them via generic_make_request(), > then these IO will be mapped to other live hctx for dispatch > > Please comment & review, thanks! > Hi Ming, FWIW, to me this series looks reasonable. So you have plans to post an updated "[PATCH 0/9] blk-mq/scsi: convert private reply queue into blk_mq hw queue" then? All the best, John > > Ming Lei (7): > blk-mq: add new state of BLK_MQ_S_INTERNAL_STOPPED > blk-mq: add blk-mq flag of BLK_MQ_F_NO_MANAGED_IRQ > blk-mq: stop to handle IO before hctx's all CPUs become offline > blk-mq: add callback of .free_request > SCSI: implement .free_request callback > blk-mq: re-submit IO in case that hctx is dead > blk-mq: handle requests dispatched from IO scheduler in case that hctx > is dead > > block/blk-mq-debugfs.c | 2 + > block/blk-mq-tag.c | 2 +- > block/blk-mq-tag.h | 2 + > block/blk-mq.c | 147 ++++++++++++++++++++++++++++++++++--- > block/blk-mq.h | 3 +- > drivers/block/loop.c | 2 +- > drivers/md/dm-rq.c | 2 +- > drivers/scsi/scsi_lib.c | 13 ++++ > include/linux/blk-mq.h | 12 +++ > include/linux/cpuhotplug.h | 1 + > 10 files changed, 170 insertions(+), 16 deletions(-) > > Cc: Bart Van Assche > Cc: Hannes Reinecke > Cc: Christoph Hellwig > Cc: Thomas Gleixner > Cc: Keith Busch > >