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=-4.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 C1F99C433E2 for ; Tue, 14 Jul 2020 12:05:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A2A7522203 for ; Tue, 14 Jul 2020 12:05:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Db1ynEQ4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726770AbgGNMFH (ORCPT ); Tue, 14 Jul 2020 08:05:07 -0400 Received: from us-smtp-2.mimecast.com ([205.139.110.61]:24339 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726332AbgGNMFH (ORCPT ); Tue, 14 Jul 2020 08:05:07 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1594728306; 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: in-reply-to:in-reply-to:references:references; bh=wLFpwPALQaMw7V+5hH97aK5GuabLV1b+VtMlx9TuSek=; b=Db1ynEQ4t2fKV6R8PrF+RF3b14HWtHo2OuLmsdeDN4DcljIWI8wtdlesCxZRr5ptijCFY/ pEFl+vAdRIY4zSBNQlpHes39p4k+gonH6XSd36vB3xTQ8dim8YA+rxU3mMXRBUymPVNho0 52izddgLVwp2wQvI8EwVJUlczHUAAOc= 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-224-FQb8WSDJMsuxqlvVoUkw_w-1; Tue, 14 Jul 2020 08:05:02 -0400 X-MC-Unique: FQb8WSDJMsuxqlvVoUkw_w-1 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 62EE4100A8EB; Tue, 14 Jul 2020 12:04:59 +0000 (UTC) Received: from T590 (ovpn-13-177.pek2.redhat.com [10.72.13.177]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4775872E62; Tue, 14 Jul 2020 12:04:47 +0000 (UTC) Date: Tue, 14 Jul 2020 20:04:43 +0800 From: Ming Lei To: John Garry Cc: Hannes Reinecke , don.brace@microsemi.com, axboe@kernel.dk, jejb@linux.ibm.com, martin.petersen@oracle.com, kashyap.desai@broadcom.com, sumit.saxena@broadcom.com, bvanassche@acm.org, hare@suse.com, hch@lst.de, shivasharan.srikanteshwara@broadcom.com, linux-block@vger.kernel.org, linux-scsi@vger.kernel.org, esc.storagedev@microsemi.com, chenxiang66@hisilicon.com, megaraidlinux.pdl@broadcom.com Subject: Re: [PATCH RFC v7 12/12] hpsa: enable host_tagset and switch to MQ Message-ID: <20200714120443.GC602708@T590> References: <1591810159-240929-1-git-send-email-john.garry@huawei.com> <1591810159-240929-13-git-send-email-john.garry@huawei.com> <939891db-a584-1ff7-d6a0-3857e4257d3e@huawei.com> <3b3ead84-5d2f-dcf2-33d5-6aa12d5d9f7e@suse.de> <4319615a-220b-3629-3bf4-1e7fd2d27b92@huawei.com> <20200714080631.GA600766@T590> <3584bcc3-830a-d50d-bb55-8ac0b686cdc0@huawei.com> <799af415-cb02-278e-1af2-c6179a94a8a8@suse.de> <20200714104437.GB602708@T590> <2da0e06c-f6b5-ee5a-1806-e5356ccf8841@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2da0e06c-f6b5-ee5a-1806-e5356ccf8841@huawei.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Tue, Jul 14, 2020 at 11:52:52AM +0100, John Garry wrote: > > > > In my machine, there are 32 queues(32 cpu cores), each queue has 1013 > > tags, so there can be 32*1013 requests coming from block layer, meantime > > smartpqi can only handles 1013 requests. I guess it isn't hard to > > trigger softlock by running heavy/concurrent smartpqi IO. > > Since pqi_alloc_io_request() does not use spinlock, disable preemption, rcu read lock is held when calling .queue_rq(), and preempt_disable() is implied in case that CONFIG_PREEMPT_RCU is off. A CPU looping in an RCU read-side critical section may cause some related issues, cause RCU's CPU Stall Detector will warn on that. > etc., so I guess that there is more of a chance of simply IO timeout. > > But I see in pqi_get_physical_disk_info() that there is some intelligence to > set the queue depth, which may reduce chance of timeout (by reducing disk > queue depth). Not sure. It may not work, see: [root@hp-dl380g10-01 mingl]# cat /sys/block/sd[a-f]/device/queue_depth 1013 1013 1013 1013 1013 1013 All sd[a-f] are smartpqi LUNs. Thanks, Ming