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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 469A4C433EF for ; Thu, 25 Nov 2021 14:11:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1355703AbhKYOOt (ORCPT ); Thu, 25 Nov 2021 09:14:49 -0500 Received: from frasgout.his.huawei.com ([185.176.79.56]:4167 "EHLO frasgout.his.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1353108AbhKYOMs (ORCPT ); Thu, 25 Nov 2021 09:12:48 -0500 Received: from fraeml711-chm.china.huawei.com (unknown [172.18.147.206]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4J0KV43KQVz689Kb; Thu, 25 Nov 2021 22:08:28 +0800 (CST) Received: from lhreml724-chm.china.huawei.com (10.201.108.75) by fraeml711-chm.china.huawei.com (10.206.15.60) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.20; Thu, 25 Nov 2021 15:09:34 +0100 Received: from [10.202.227.179] (10.202.227.179) 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 15.1.2308.20; Thu, 25 Nov 2021 14:09:34 +0000 Subject: Re: [PATCH RFT 0/3] blk-mq: Optimise blk_mq_queue_tag_busy_iter() for shared tags To: Kashyap Desai , CC: , , , References: <1635852455-39935-1-git-send-email-john.garry@huawei.com> <7fba1b1e-63a6-6315-e5ca-6d5ae9de6dbb@huawei.com> From: John Garry Message-ID: <9859e133-e3b8-4e53-dfad-cbf75ed3102f@huawei.com> Date: Thu, 25 Nov 2021 14:09:33 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.12.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.202.227.179] X-ClientProxiedBy: lhreml723-chm.china.huawei.com (10.201.108.74) To lhreml724-chm.china.huawei.com (10.201.108.75) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 25/11/2021 13:46, Kashyap Desai wrote: >> John - >> >> I will try something this week and let you know. > John - I tested patchset and looks good. Issue reported at below thread is > fixed. > https://lore.kernel.org/linux-block/e4e92abbe9d52bcba6b8cc6c91c442cc@mail.gmail.com/ > > Here is perf top data. > > 5.70% [megaraid_sas] [k] complete_cmd_fusion > 3.80% [megaraid_sas] [k] > megasas_build_and_issue_cmd_fusion > 2.75% [kernel] [k] syscall_return_via_sysret > 2.68% [kernel] [k] entry_SYSCALL_64 > 2.22% [kernel] [k] io_submit_one > 2.19% [megaraid_sas] [k] megasas_build_ldio_fusion > 1.95% [kernel] [k] llist_add_batch > 1.80% [kernel] [k] llist_reverse_order > 1.79% [kernel] [k] scsi_complete > 1.73% [kernel] [k] scsi_queue_rq > 1.66% [kernel] [k] check_preemption_disabled > 1.37% [megaraid_sas] [k] megasas_queue_command > 1.16% [kernel] [k] native_irq_return_iret > 1.11% [kernel] [k] aio_complete_rw > 1.07% [kernel] [k] read_tsc > 1.06% fio [.] __fio_gettime > 1.05% [kernel] [k] flush_smp_call_function_queue > 1.03% [kernel] [k] blk_complete_reqs > 1.00% [kernel] [k] blk_mq_free_request > 0.98% [kernel] [k] sbitmap_get > > > I will continue testing and let you know how it goes. ok, good to know, thanks. But I would still like to know what is triggering blk_mq_queue_tag_busy_iter() so often. Indeed, as mentioned in this cover letter, this function was hardly optimised before for shared sbitmap. And any opinion whether we would want this as a fix? Information requested above would help explain why we would need it as a fix. Cheers, John