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 51C38C433E0 for ; Tue, 5 Jan 2021 11:40:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0CBC0229C7 for ; Tue, 5 Jan 2021 11:40:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728509AbhAELkc (ORCPT ); Tue, 5 Jan 2021 06:40:32 -0500 Received: from frasgout.his.huawei.com ([185.176.79.56]:2292 "EHLO frasgout.his.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728452AbhAELkc (ORCPT ); Tue, 5 Jan 2021 06:40:32 -0500 Received: from fraeml741-chm.china.huawei.com (unknown [172.18.147.206]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4D99Qf4h1Dz67VyY; Tue, 5 Jan 2021 19:35:06 +0800 (CST) Received: from lhreml724-chm.china.huawei.com (10.201.108.75) by fraeml741-chm.china.huawei.com (10.206.15.222) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2106.2; Tue, 5 Jan 2021 12:39:49 +0100 Received: from [10.47.9.197] (10.47.9.197) 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 15.1.2106.2; Tue, 5 Jan 2021 11:39:49 +0000 Subject: Re: [PATCH] blk-mq: test QUEUE_FLAG_HCTX_ACTIVE for sbitmap_shared in hctx_may_queue To: Ming Lei CC: Jens Axboe , , Kashyap Desai References: <20201227113458.3289082-1-ming.lei@redhat.com> <20210105022017.GA3594357@T590> <20210105111850.GB3619109@T590> From: John Garry Message-ID: Date: Tue, 5 Jan 2021 11:38:48 +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: <20210105111850.GB3619109@T590> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.47.9.197] X-ClientProxiedBy: lhreml727-chm.china.huawei.com (10.201.108.78) To lhreml724-chm.china.huawei.com (10.201.108.75) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 05/01/2021 11:18, Ming Lei wrote: >>>> ot set normally.. >>> It always return true, and might just take a bit more CPU especially the tag queue >>> depth of magsas_raid and hisi_sas_v3 is quite high. >> Hi Ming, >> >> Right, but we actually tested by hacking the host tag queue depth to be >> lower such that we should have tag contention, here is an extract from the >> original series cover letter for my results: >> >> Tag depth 4000 (default) 260** >> >> Baseline (v5.9-rc1): >> none sched: 2094K IOPS 513K >> mq-deadline sched: 2145K IOPS 1336K >> >> Final, host_tagset=0 in LLDD *, ***: >> none sched: 2120K IOPS 550K >> mq-deadline sched: 2121K IOPS 1309K >> >> Final ***: >> none sched: 2132K IOPS 1185 >> mq-deadline sched: 2145K IOPS 2097 >> >> Maybe my test did not expose the issue. Kashyap also tested this and >> reported the original issue such that we needed this feature, so I'm >> confused. Hi Ming, > How many LUNs are involved in above test with 260 depth? For me, there was 12 SAS SSDs; for convenience here is the cover letter with details: https://lore.kernel.org/linux-block/1597850436-116171-1-git-send-email-john.garry@huawei.com/ IIRC, for megaraid sas, Kashyap used many more LUNs for testing (64) and high fio depth (128) but did not reduce .can_queue, topic originally raised here: https://lore.kernel.org/linux-block/29f8062c1fccace73c45252073232917@mail.gmail.com/ Thanks, John