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 841A2C17441 for ; Mon, 11 Nov 2019 14:02:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5AE5B21783 for ; Mon, 11 Nov 2019 14:02:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726903AbfKKOCa (ORCPT ); Mon, 11 Nov 2019 09:02:30 -0500 Received: from lhrrgout.huawei.com ([185.176.76.210]:2082 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726811AbfKKOCa (ORCPT ); Mon, 11 Nov 2019 09:02:30 -0500 Received: from lhreml703-cah.china.huawei.com (unknown [172.18.7.107]) by Forcepoint Email with ESMTP id C723AA11B5AAFA1A164C; Mon, 11 Nov 2019 14:02:28 +0000 (GMT) Received: from lhreml724-chm.china.huawei.com (10.201.108.75) by lhreml703-cah.china.huawei.com (10.201.108.44) with Microsoft SMTP Server (TLS) id 14.3.408.0; Mon, 11 Nov 2019 14:02:27 +0000 Received: from [127.0.0.1] (10.202.226.46) 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 15.1.1713.5; Mon, 11 Nov 2019 14:02:28 +0000 Subject: Re: [PATCH 6/6] scsi: hisi_sas: Expose multiple hw queues for v3 as experimental To: Ming Lei CC: , , , , , References: <1571926881-75524-1-git-send-email-john.garry@huawei.com> <1571926881-75524-7-git-send-email-john.garry@huawei.com> <20191027081910.GB16704@ming.t460p> From: John Garry Message-ID: Date: Mon, 11 Nov 2019 14:02:27 +0000 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: <20191027081910.GB16704@ming.t460p> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.202.226.46] X-ClientProxiedBy: lhreml713-chm.china.huawei.com (10.201.108.64) 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 27/10/2019 08:19, Ming Lei wrote: >> .this_id = -1, >> @@ -3265,8 +3300,14 @@ hisi_sas_v3_probe(struct pci_dev *pdev, const struct pci_device_id *id) >> shost->max_lun = ~0; >> shost->max_channel = 1; >> shost->max_cmd_len = 16; >> - shost->can_queue = HISI_SAS_UNRESERVED_IPTT; >> - shost->cmd_per_lun = HISI_SAS_UNRESERVED_IPTT; >> + Hi Ming, I mentioned in the thread "blk-mq: improvement on handling IO during CPU hotplug" that I was using this series to test that patchset. So just with this patchset (and without yours), I get what looks like some IO errors in the LLDD. The error is an underflow error. I can't figure out what is the cause. I'm wondering if the SCSI command is getting corrupted someway. >> + if (expose_mq_experimental) { >> + shost->can_queue = HISI_SAS_MAX_COMMANDS; >> + shost->cmd_per_lun = HISI_SAS_MAX_COMMANDS; > The above is contradictory with current 'nr_hw_queues''s meaning, > see commit on Scsi_Host.nr_hw_queues. > Right, so I am generating the hostwide tag in the LLDD. And the Scsi host-wide host_busy counter should ensure that we don't pump too much IO to the HBA. What other problem will this cause? Thanks, John > > /* > * In scsi-mq mode, the number of hardware queues supported by the LLD. > * > * Note: it is assumed that each hardware queue has a queue depth of > * can_queue. In other words, the total queue depth per host > * is nr_hw_queues * can_queue. > */ > > Also this implementation wastes memory too much. > > > thanks, > Ming