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=-6.9 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,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 81CB2C433F5 for ; Wed, 15 Sep 2021 07:49:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 61DA060F92 for ; Wed, 15 Sep 2021 07:49:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236634AbhIOHuT (ORCPT ); Wed, 15 Sep 2021 03:50:19 -0400 Received: from szxga02-in.huawei.com ([45.249.212.188]:15418 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236647AbhIOHtP (ORCPT ); Wed, 15 Sep 2021 03:49:15 -0400 Received: from dggemv703-chm.china.huawei.com (unknown [172.30.72.53]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4H8XK06ch5zRBs0; Wed, 15 Sep 2021 15:43:48 +0800 (CST) Received: from dggema762-chm.china.huawei.com (10.1.198.204) by dggemv703-chm.china.huawei.com (10.3.19.46) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2308.8; Wed, 15 Sep 2021 15:47:55 +0800 Received: from [10.174.176.73] (10.174.176.73) by dggema762-chm.china.huawei.com (10.1.198.204) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2308.8; Wed, 15 Sep 2021 15:47:54 +0800 Subject: Re: [PATCH v2 4/4] block, bfq: consider request size in bfq_asymmetric_scenario() To: Paolo Valente CC: Jens Axboe , linux-block , , References: <20210806020826.1407257-1-yukuai3@huawei.com> <20210806020826.1407257-5-yukuai3@huawei.com> <8601F280-2F16-446A-95BA-37A07D1A1055@linaro.org> <143fa1a2-de5f-b18a-73d9-8e105844709c@huawei.com> <68A2B4C8-48A5-45F3-8782-2440C0028161@linaro.org> From: "yukuai (C)" Message-ID: Date: Wed, 15 Sep 2021 15:47:54 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <68A2B4C8-48A5-45F3-8782-2440C0028161@linaro.org> Content-Type: text/plain; charset="gbk"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.176.73] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggema762-chm.china.huawei.com (10.1.198.204) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 2021/09/15 15:36, Paolo Valente wrote: > > >> Il giorno 7 set 2021, alle ore 13:29, yukuai (C) ha scritto: >> >> On 2021/08/27 1:00, Paolo Valente wrote: >>>> Il giorno 6 ago 2021, alle ore 04:08, Yu Kuai ha scritto: >>>> >>>> There is a special case when bfq do not need to idle when more than >>>> one groups is active: >>>> >>> Unfortunately, there is a misunderstanding here. If more than one >>> group is active, then idling is not needed only if a lot of symmetry >>> conditions also hold: >>> - all active groups have the same weight >>> - all active groups contain the same number of active queues >> >> Hi, Paolo >> >> I didn't think of this contition. >> >> It's seems that if we want to idle when more than one group is active, >> there are two additional conditions: >> >> - all dispatched requests have the same size >> - all active groups contain the same number of active queues >> > > Also the weights and the I/O priorities of the queues inside the > groups needs to be controlled, unfortunately. > >> Thus we still need to track how many queues are active in each group. >> The conditions seems to be too much, do you think is it worth it to >> add support to idle when more than one group is active? >> > > I think I see your point. The problem is that these states are > dynamic. So, if we suspend tracking all the above information while > more than one group is active, then we are with no state in case only > one group remains active. Hi, Paolo In this case, I'll drop the last two patches in the next iteration. Thanks, Kuai