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=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 01685ECE58C for ; Mon, 7 Oct 2019 15:01:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CFF962070B for ; Mon, 7 Oct 2019 15:01:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727753AbfJGPBS (ORCPT ); Mon, 7 Oct 2019 11:01:18 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48712 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727490AbfJGPBS (ORCPT ); Mon, 7 Oct 2019 11:01:18 -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 7564488D316; Mon, 7 Oct 2019 15:01:17 +0000 (UTC) Received: from ming.t460p (ovpn-8-21.pek2.redhat.com [10.72.8.21]) by smtp.corp.redhat.com (Postfix) with ESMTPS id EA4A95D9CD; Mon, 7 Oct 2019 15:01:07 +0000 (UTC) Date: Mon, 7 Oct 2019 23:01:02 +0800 From: Ming Lei To: Hannes Reinecke Cc: Jens Axboe , linux-block@vger.kernel.org, John Garry , Bart Van Assche , Hannes Reinecke , Christoph Hellwig , Thomas Gleixner , Keith Busch Subject: Re: [PATCH V2 RESEND 3/5] blk-mq: stop to handle IO before hctx's all CPUs become offline Message-ID: <20191007150101.GA1668@ming.t460p> References: <20191006024516.19996-1-ming.lei@redhat.com> <20191006024516.19996-4-ming.lei@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.11.3 (2019-02-01) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.69]); Mon, 07 Oct 2019 15:01:17 +0000 (UTC) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Mon, Oct 07, 2019 at 08:23:29AM +0200, Hannes Reinecke wrote: > On 10/6/19 4:45 AM, Ming Lei wrote: > > Most of blk-mq drivers depend on managed IRQ's auto-affinity to setup > > up queue mapping. Thomas mentioned the following point[1]: > > > > " > > 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. > > " > > > > However, current blk-mq implementation doesn't quiesce hw queue before > > the last CPU in the hctx is shutdown. Even worse, CPUHP_BLK_MQ_DEAD is > > one cpuhp state handled after the CPU is down, so there isn't any chance > > to quiesce hctx for blk-mq wrt. CPU hotplug. > > > > Add new cpuhp state of CPUHP_AP_BLK_MQ_ONLINE for blk-mq to stop queues > > and wait for completion of in-flight requests. > > > > [1] https://lore.kernel.org/linux-block/alpine.DEB.2.21.1904051331270.1802@nanos.tec.linutronix.de/ > > > > Cc: Bart Van Assche > > Cc: Hannes Reinecke > > Cc: Christoph Hellwig > > Cc: Thomas Gleixner > > Cc: Keith Busch > > Signed-off-by: Ming Lei > > --- > > block/blk-mq-tag.c | 2 +- > > block/blk-mq-tag.h | 2 ++ > > block/blk-mq.c | 65 ++++++++++++++++++++++++++++++++++++++ > > include/linux/blk-mq.h | 1 + > > include/linux/cpuhotplug.h | 1 + > > 5 files changed, 70 insertions(+), 1 deletion(-) > > > I really don't like the zillions of 'XXX_in_flight()' helper in blk-mq; > blk_mq_queue_inflight(), blk_mq_in_flight(), blk_mq_in_flight_rw() et al. > Can't you implement your one on top of the already existing? This one returns in-flight rqs on specific tags(hctx), so far no such kind of interface, that is why blk_mq_all_tag_busy_iter is exported out in this patch. Thanks, Ming