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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,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 6DEE9CA9EC0 for ; Tue, 29 Oct 2019 01:50:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3962221721 for ; Tue, 29 Oct 2019 01:50:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="VqKUACb3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728889AbfJ2Bu2 (ORCPT ); Mon, 28 Oct 2019 21:50:28 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:43303 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727364AbfJ2Bu2 (ORCPT ); Mon, 28 Oct 2019 21:50:28 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1572313827; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=UVHONl7yjJBla4/AnLrbww4CmGj4mlbMPxZ9EJNJ4Qw=; b=VqKUACb3COQZgmJhPtZJ/GRa419TY3iiD7M3AyVy2iX7Q2aWjwLw8GyRqzprH8IPzUSoZV J6IYxRJjM6xES+wPZ0qX+A0ez6oR69roy3Qfza2sclZNZPNB+JN+pdorM1HaLUFxlwW8B+ valeA3O+Euubxk5FlA0nZCh4Yoc6wI8= 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-190-PoOJTGUzN1ey9Pdm_IlwYw-1; Mon, 28 Oct 2019 21:50:23 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id EC6831005509; Tue, 29 Oct 2019 01:50:21 +0000 (UTC) Received: from ming.t460p (ovpn-8-18.pek2.redhat.com [10.72.8.18]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3BAEB600C1; Tue, 29 Oct 2019 01:50:14 +0000 (UTC) Date: Tue, 29 Oct 2019 09:50:09 +0800 From: Ming Lei To: John Garry Cc: Jens Axboe , "linux-block@vger.kernel.org" , Bart Van Assche , Hannes Reinecke , Christoph Hellwig , Thomas Gleixner , Keith Busch Subject: Re: [PATCH V4 0/5] blk-mq: improvement on handling IO during CPU hotplug Message-ID: <20191029015009.GD22088@ming.t460p> References: <20191014015043.25029-1-ming.lei@redhat.com> <20191016120729.GB5515@ming.t460p> <9dbc14ab-65cd-f7ac-384c-2dbe03575ee7@huawei.com> <55a84ea3-647d-0a76-596c-c6c6b2fc1b75@huawei.com> <20191020101404.GA5103@ming.t460p> <10aac76a-26bb-bcda-c6ea-b39ca66d6740@huawei.com> <20191028104238.GA14008@ming.t460p> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-MC-Unique: PoOJTGUzN1ey9Pdm_IlwYw-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Mon, Oct 28, 2019 at 11:55:42AM +0000, John Garry wrote: > > >=20 > > > For the SCSI commands which timeout, I notice that > > > scsi_set_blocked(reason=3DSCSI_MLQUEUE_EH_RETRY) was called 30 second= s > > > earlier. > > >=20 > > > scsi_set_blocked+0x20/0xb8 > > > __scsi_queue_insert+0x40/0x90 > > > scsi_softirq_done+0x164/0x1c8 > > > __blk_mq_complete_request_remote+0x18/0x20 > > > flush_smp_call_function_queue+0xa8/0x150 > > > generic_smp_call_function_single_interrupt+0x10/0x18 > > > handle_IPI+0xec/0x1a8 > > > arch_cpu_idle+0x10/0x18 > > > do_idle+0x1d0/0x2b0 > > > cpu_startup_entry+0x24/0x40 > > > secondary_start_kernel+0x1b4/0x208 > >=20 > > Could you investigate a bit the reason why timeout is triggered? >=20 > Yeah, it does seem a strange coincidence that the SCSI command even faile= d > and we have to retry, since these should be uncommon events. I'll check o= n > this LLDD error. >=20 > >=20 > > Especially we suppose to drain all in-flight requests before the > > last CPU of this hctx becomes offline, and it shouldn't be caused by > > the hctx becoming dead, so still need you to confirm that all > > in-flight requests are really drained in your test. >=20 > ok >=20 > Or is it still > > possible to dispatch to LDD after BLK_MQ_S_INTERNAL_STOPPED is set? >=20 > It shouldn't be. However it would seem that this IO had been dispatched t= o > the LLDD, the hctx dies, and then we attempt to requeue on that hctx. But this patch does wait for completion of in-flight request before shutdown the last CPU of this hctx. Thanks, Ming