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=-7.5 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 E5746C432BE for ; Thu, 2 Sep 2021 13:31:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CDE2D60525 for ; Thu, 2 Sep 2021 13:31:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345256AbhIBNc2 (ORCPT ); Thu, 2 Sep 2021 09:32:28 -0400 Received: from szxga01-in.huawei.com ([45.249.212.187]:9000 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345255AbhIBNc1 (ORCPT ); Thu, 2 Sep 2021 09:32:27 -0400 Received: from dggemv703-chm.china.huawei.com (unknown [172.30.72.55]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4H0hdH4vQ9zYx1r; Thu, 2 Sep 2021 21:30:43 +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 15.1.2176.2; Thu, 2 Sep 2021 21:31:27 +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; Thu, 2 Sep 2021 21:31:27 +0800 Subject: Re: [PATCH v2 2/4] block, bfq: do not idle if only one cgroup is activated To: Paolo Valente CC: Jens Axboe , , , References: <20210806020826.1407257-1-yukuai3@huawei.com> <20210806020826.1407257-3-yukuai3@huawei.com> <21FA636D-2C21-4ACD-B7DE-180ABB1F3562@linaro.org> From: "yukuai (C)" Message-ID: Date: Thu, 2 Sep 2021 21:31:26 +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: <21FA636D-2C21-4ACD-B7DE-180ABB1F3562@linaro.org> Content-Type: text/plain; charset="gbk"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.176.73] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) 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 2021/08/27 1:00, Paolo Valente wrote: > > Why do you make these extensive changes, while you can leave all the > function unchanged and just modify the above condition to something > like > > || bfqd->num_groups_with_pending_reqs > 1 > || (bfqd->num_groups_with_pending_reqs && bfqd->num_queues_with_pending_reqs_in_root) Hi, Paolo I was thinking that if CONFIG_BFQ_GROUP_IOSCHED is enabled, there is no need to caculate smallest_weight, varied_queue_weights, and multiple_classes_busy: If we count root group into num_groups_with_pending_reqs - If num_groups_with_pending_reqs <= 1, idle is not needed - If num_groups_with_pending_reqs > 1, idle is needed Thus such changes can save some additional overhead. Thanks Yu Kuai > > In addition, I still wonder whether you can simply add also the root > group to bfqd->num_groups_with_pending_reqs (when the root group is > active). This would make the design much cleaner. > > Thanks, > Paolo > >> -#endif >> - ; >> + return varied_queue_weights || multiple_classes_busy; >> } >> >> /* >> -- >> 2.31.1 >> > > . >