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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 82D22C2D0EA for ; Wed, 8 Apr 2020 13:01:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4E71B206F7 for ; Wed, 8 Apr 2020 13:01:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728113AbgDHNBh (ORCPT ); Wed, 8 Apr 2020 09:01:37 -0400 Received: from lhrrgout.huawei.com ([185.176.76.210]:2642 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727896AbgDHNBh (ORCPT ); Wed, 8 Apr 2020 09:01:37 -0400 Received: from lhreml724-chm.china.huawei.com (unknown [172.18.7.107]) by Forcepoint Email with ESMTP id 976F3C556FD4BE171BCF; Wed, 8 Apr 2020 14:01:35 +0100 (IST) Received: from [127.0.0.1] (10.210.166.224) by lhreml724-chm.china.huawei.com (10.201.108.75) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1913.5; Wed, 8 Apr 2020 14:01:34 +0100 Subject: Re: [PATCH V6 0/8] blk-mq: improvement CPU hotplug To: Daniel Wagner , Ming Lei CC: Jens Axboe , , Bart Van Assche , Hannes Reinecke , Christoph Hellwig , Thomas Gleixner References: <20200407092901.314228-1-ming.lei@redhat.com> <20200408124017.g6wizq5bljzwb2gq@beryllium.lan> From: John Garry Message-ID: Date: Wed, 8 Apr 2020 14:01:11 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.1.2 MIME-Version: 1.0 In-Reply-To: <20200408124017.g6wizq5bljzwb2gq@beryllium.lan> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.210.166.224] X-ClientProxiedBy: lhreml738-chm.china.huawei.com (10.201.108.188) To lhreml724-chm.china.huawei.com (10.201.108.75) X-CFilter-Loop: Reflected Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 08/04/2020 13:40, Daniel Wagner wrote: > Hi Ming, > > On Tue, Apr 07, 2020 at 05:28:53PM +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 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! > > FWIW, I've stress test this series by running the stress-cpu-hotplug > with a fio workload in the background. Nothing exploded, all just > worked fine. Hi Daniel, Is stress-cpu-hotplug an ltp test? or from Steven Rostedt - I saw some threads where he mentioned some script? Will the fio processes migrate back onto cpus which have been onlined again? What is the block driver NVMe? Thanks, john