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 EB4FAC31E40 for ; Mon, 12 Aug 2019 13:46:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CA33320665 for ; Mon, 12 Aug 2019 13:46:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726703AbfHLNqY (ORCPT ); Mon, 12 Aug 2019 09:46:24 -0400 Received: from mx1.redhat.com ([209.132.183.28]:42210 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726538AbfHLNqY (ORCPT ); Mon, 12 Aug 2019 09:46:24 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id DE0D9300501D; Mon, 12 Aug 2019 13:46:23 +0000 (UTC) Received: from ming.t460p (ovpn-8-23.pek2.redhat.com [10.72.8.23]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 2D8C75D6B2; Mon, 12 Aug 2019 13:46:16 +0000 (UTC) Date: Mon, 12 Aug 2019 21:46:09 +0800 From: Ming Lei To: Jens Axboe , John Garry Cc: linux-block@vger.kernel.org, Minwoo Im , Bart Van Assche , Hannes Reinecke , Christoph Hellwig , Thomas Gleixner , Keith Busch Subject: Re: [PATCH V2 0/5] blk-mq: improvement on handling IO during CPU hotplug Message-ID: <20190812134608.GA16803@ming.t460p> References: <20190812134312.16732-1-ming.lei@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190812134312.16732-1-ming.lei@redhat.com> User-Agent: Mutt/1.11.3 (2019-02-01) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.48]); Mon, 12 Aug 2019 13:46:24 +0000 (UTC) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Hi John, On Mon, Aug 12, 2019 at 09:43:07PM +0800, Ming Lei wrote: > 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! > > V2: > - patch4 & patch 5 in V1 have been merged to block tree, so remove > them > - address comments from John Garry and Minwoo > > > Ming Lei (5): > 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: 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 | 143 +++++++++++++++++++++++++++++++++---- > block/blk-mq.h | 3 +- > drivers/block/loop.c | 2 +- > drivers/md/dm-rq.c | 2 +- > include/linux/blk-mq.h | 5 ++ > include/linux/cpuhotplug.h | 1 + > 9 files changed, 146 insertions(+), 16 deletions(-) > > Cc: Bart Van Assche > Cc: Hannes Reinecke > Cc: Christoph Hellwig > Cc: Thomas Gleixner > Cc: Keith Busch > -- > 2.20.1 > Sorry for forgetting to Cc you. Thanks, Ming