From patchwork Mon Oct 14 01:50:38 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ming Lei X-Patchwork-Id: 11187683 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id F0FFB1668 for ; Mon, 14 Oct 2019 01:50:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DA18A20815 for ; Mon, 14 Oct 2019 01:50:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729652AbfJNBuy (ORCPT ); Sun, 13 Oct 2019 21:50:54 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54766 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729630AbfJNBuy (ORCPT ); Sun, 13 Oct 2019 21:50:54 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8681A308FBFC; Mon, 14 Oct 2019 01:50:53 +0000 (UTC) Received: from localhost (ovpn-8-17.pek2.redhat.com [10.72.8.17]) by smtp.corp.redhat.com (Postfix) with ESMTP id 07DC85D9C9; Mon, 14 Oct 2019 01:50:49 +0000 (UTC) From: Ming Lei To: Jens Axboe Cc: linux-block@vger.kernel.org, Ming Lei , John Garry , Bart Van Assche , Hannes Reinecke , Christoph Hellwig , Thomas Gleixner , Keith Busch Subject: [PATCH V4 0/5] blk-mq: improvement on handling IO during CPU hotplug Date: Mon, 14 Oct 2019 09:50:38 +0800 Message-Id: <20191014015043.25029-1-ming.lei@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.43]); Mon, 14 Oct 2019 01:50:54 +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! John, I don't add your tested-by tag since V3 have some changes, and I appreciate if you may run your test on V3. V4: - resubmit IOs in dispatch list in case that this hctx is dead V3: - re-organize patch 2 & 3 a bit for addressing Hannes's comment - fix patch 4 for avoiding potential deadlock, as found by Hannes 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: prepare for draining IO when hctx's all CPUs are offline blk-mq: stop to handle IO and drain IO before hctx becomes dead 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 | 137 ++++++++++++++++++++++++++++++++++--- 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, 141 insertions(+), 15 deletions(-) Cc: John Garry Cc: Bart Van Assche Cc: Hannes Reinecke Cc: Christoph Hellwig Cc: Thomas Gleixner Cc: Keith Busch Tested-by: Xiang Chen