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=-6.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 D63A1C2BABC for ; Tue, 7 Apr 2020 09:29:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AACF420769 for ; Tue, 7 Apr 2020 09:29:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="BAZ62IVZ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728068AbgDGJ3T (ORCPT ); Tue, 7 Apr 2020 05:29:19 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:44612 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726353AbgDGJ3S (ORCPT ); Tue, 7 Apr 2020 05:29:18 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1586251757; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=zRmYnW7628q203AnRkZmBOZvzAxfTlhPlz81qkx3SUY=; b=BAZ62IVZpMfMO/bCi496z/hVpeLH6WuWuClpucfdu5jkAn5RSjz5v2HCiNX3aEUsjILDwn da/ypJcEPw+bC8f+gbN2zIn5gCfKimn/FuAU2Ll9qS4BfURITWIqnRXRNBEif3DVNmnpqL jiLhpTinpsKrlC16YhQM0RtuKMO6zkw= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-327-G2G_czmxPXWfzGhh3rFwTQ-1; Tue, 07 Apr 2020 05:29:12 -0400 X-MC-Unique: G2G_czmxPXWfzGhh3rFwTQ-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 3B4AF800D50; Tue, 7 Apr 2020 09:29:11 +0000 (UTC) Received: from localhost (ovpn-8-23.pek2.redhat.com [10.72.8.23]) by smtp.corp.redhat.com (Postfix) with ESMTP id 902F392F83; Tue, 7 Apr 2020 09:29:07 +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 Subject: [PATCH V6 0/8] blk-mq: improvement CPU hotplug Date: Tue, 7 Apr 2020 17:28:53 +0800 Message-Id: <20200407092901.314228-1-ming.lei@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Content-Transfer-Encoding: quoted-printable 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 beginnin= g: =20 The driver/subsystem has to quiesce the interrupt line and the asso= ciated queue _before_ it gets shutdown in CPU unplug and not fiddle with i= t 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 inactive(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! https://github.com/ming1/linux/commits/v5.6-blk-mq-improve-cpu-hotplug V6: - simplify getting driver tag, so that we can drain in-flight requests correctly without using synchronize_rcu() - handle re-submission of flush & passthrough request correctly V5: - rename BLK_MQ_S_INTERNAL_STOPPED as BLK_MQ_S_INACTIVE - re-factor code for re-submit requests in cpu dead hotplug handler - address requeue corner case V4: - resubmit IOs in dispatch list in case that this hctx is dead=20 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 (8): blk-mq: assign rq->tag in blk_mq_get_driver_tag blk-mq: add new state of BLK_MQ_S_INACTIVE 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 inactive block: add blk_end_flush_machinery blk-mq: re-submit IO in case that hctx is inactive blk-mq: handle requests dispatched from IO scheduler in case of inactive hctx block: deactivate hctx when the hctx is actually inactive block/blk-flush.c | 143 +++++++++++++--- block/blk-mq-debugfs.c | 2 + block/blk-mq-tag.c | 2 +- block/blk-mq-tag.h | 2 + block/blk-mq.c | 331 ++++++++++++++++++++++++++++++------- block/blk-mq.h | 24 +-- block/blk.h | 9 +- drivers/block/loop.c | 2 +- drivers/md/dm-rq.c | 2 +- include/linux/blk-mq.h | 6 + include/linux/cpuhotplug.h | 1 + 11 files changed, 420 insertions(+), 104 deletions(-) Cc: John Garry Cc: Bart Van Assche Cc: Hannes Reinecke Cc: Christoph Hellwig Cc: Thomas Gleixner --=20 2.25.2