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 BEDC0C433E1 for ; Tue, 14 Jul 2020 10:37:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A7D692220E for ; Tue, 14 Jul 2020 10:37:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726936AbgGNKhD (ORCPT ); Tue, 14 Jul 2020 06:37:03 -0400 Received: from lhrrgout.huawei.com ([185.176.76.210]:2474 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725841AbgGNKhD (ORCPT ); Tue, 14 Jul 2020 06:37:03 -0400 Received: from lhreml724-chm.china.huawei.com (unknown [172.18.7.106]) by Forcepoint Email with ESMTP id D9682A742BCD71BD03E6; Tue, 14 Jul 2020 11:37:01 +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 11:37:00 +0100 Subject: Re: [PATCH RFC v7 12/12] hpsa: enable host_tagset and switch to MQ To: Hannes Reinecke , Ming Lei 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> From: John Garry Message-ID: <6b19a455-56a2-c278-5443-ccb3e3cb0379@huawei.com> Date: Tue, 14 Jul 2020 11:35:14 +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: <799af415-cb02-278e-1af2-c6179a94a8a8@suse.de> 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 On 14/07/2020 11:19, Hannes Reinecke wrote: > Correct. There is only one tagset per host, even if the host supports > several queues (guess why it's called smart PQI:-). > And mainline code isn't really wrong, it just allocates the next free > tag from the host tagset; it's not using the block-layer tags at all. > Precisely because the block layer currently cannot guarantee that tags > are unique per host. ok, but it's not exemplary in what it does. And I suppose that's why it needs to spin indefinitely for a free tag in pqi_alloc_io_request(), instead of failing immediately when none are free. > > 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. > > But anyway, I'll test it on smartpqi, too. > Great, thanks.