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=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 355BAC433E8 for ; Tue, 14 Jul 2020 10:54:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1DCEF22200 for ; Tue, 14 Jul 2020 10:54:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727029AbgGNKym (ORCPT ); Tue, 14 Jul 2020 06:54:42 -0400 Received: from lhrrgout.huawei.com ([185.176.76.210]:2475 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726766AbgGNKym (ORCPT ); Tue, 14 Jul 2020 06:54:42 -0400 Received: from lhreml724-chm.china.huawei.com (unknown [172.18.7.108]) by Forcepoint Email with ESMTP id 1DDF1E633BEEA8E59113; Tue, 14 Jul 2020 11:54:40 +0100 (IST) Received: from [127.0.0.1] (10.47.10.169) 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; Tue, 14 Jul 2020 11:54:38 +0100 Subject: Re: [PATCH RFC v7 12/12] hpsa: enable host_tagset and switch to MQ To: Ming Lei , Hannes Reinecke CC: , , , , , , , , , , , , , , 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> From: John Garry Message-ID: <2da0e06c-f6b5-ee5a-1806-e5356ccf8841@huawei.com> Date: Tue, 14 Jul 2020 11:52:52 +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: <20200714104437.GB602708@T590> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.47.10.169] 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-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org > > 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, 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. > >> >> And the point of this patchset is exactly that the block layer will only >> send up to 'can_queue' requests, irrespective on how many hardware >> queues are present. > > That is only true for shared tags. > Thanks, John