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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 C75C2C742A2 for ; Fri, 12 Jul 2019 02:47:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A60D6208E4 for ; Fri, 12 Jul 2019 02:47:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729197AbfGLCrj (ORCPT ); Thu, 11 Jul 2019 22:47:39 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60940 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729051AbfGLCrj (ORCPT ); Thu, 11 Jul 2019 22:47:39 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 25DD2C057EC6; Fri, 12 Jul 2019 02:47:39 +0000 (UTC) Received: from localhost (ovpn-8-19.pek2.redhat.com [10.72.8.19]) by smtp.corp.redhat.com (Postfix) with ESMTP id 01098600CD; Fri, 12 Jul 2019 02:47:35 +0000 (UTC) From: Ming Lei To: Jens Axboe Cc: linux-block@vger.kernel.org, "James E . J . Bottomley" , "Martin K . Petersen" , linux-scsi@vger.kernel.org, Ming Lei , Bart Van Assche , Hannes Reinecke , Christoph Hellwig , Thomas Gleixner , Keith Busch Subject: [RFC PATCH 0/7] blk-mq: improvement on handling IO during CPU hotplug Date: Fri, 12 Jul 2019 10:47:19 +0800 Message-Id: <20190712024726.1227-1-ming.lei@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Fri, 12 Jul 2019 02:47:39 +0000 (UTC) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org 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! 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 -- 2.20.1