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 0F286C433F5 for ; Mon, 25 Apr 2022 13:56:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242292AbiDYN7D (ORCPT ); Mon, 25 Apr 2022 09:59:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60110 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242294AbiDYN67 (ORCPT ); Mon, 25 Apr 2022 09:58:59 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E1FA114023; Mon, 25 Apr 2022 06:55:50 -0700 (PDT) Received: from kwepemi500020.china.huawei.com (unknown [172.30.72.56]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4Kn62m4CwNzfbCv; Mon, 25 Apr 2022 21:54:56 +0800 (CST) Received: from kwepemm600009.china.huawei.com (7.193.23.164) by kwepemi500020.china.huawei.com (7.221.188.8) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Mon, 25 Apr 2022 21:55:48 +0800 Received: from [10.174.176.73] (10.174.176.73) by kwepemm600009.china.huawei.com (7.193.23.164) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Mon, 25 Apr 2022 21:55:47 +0800 Subject: Re: [PATCH -next v2 2/5] block, bfq: add fake weight_counter for weight-raised queue From: "yukuai (C)" To: Jan Kara CC: , , , , , , References: <20220416093753.3054696-1-yukuai3@huawei.com> <20220416093753.3054696-3-yukuai3@huawei.com> <20220425094856.qgkhba2klguduxot@quack3.lan> Message-ID: <4048cc0c-adc8-8097-4a40-762137c4c282@huawei.com> Date: Mon, 25 Apr 2022 21:55:46 +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: Content-Type: text/plain; charset="gbk"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.176.73] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To kwepemm600009.china.huawei.com (7.193.23.164) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ÔÚ 2022/04/25 21:34, yukuai (C) дµÀ: > ÔÚ 2022/04/25 17:48, Jan Kara дµÀ: >> On Sat 16-04-22 17:37:50, Yu Kuai wrote: >>> Weight-raised queue is not inserted to weights_tree, which makes it >>> impossible to track how many queues have pending requests through >>> weights_tree insertion and removel. This patch add fake weight_counter >>> for weight-raised queue to do that. >>> >>> Signed-off-by: Yu Kuai >> >> This is a bit hacky. I was looking into a better place where to hook to >> count entities in a bfq_group with requests and I think >> bfq_add_bfqq_busy() >> and bfq_del_bfqq_busy() are ideal for this. It also makes better sense >> conceptually than hooking into weights tree handling. >> > Hi, > > bfq_del_bfqq_busy() will be called when all the reqs in the bfqq are > dispatched, however there might still some reqs are't completed yet. > > Here what we want to track is how many bfqqs have pending reqs, > specifically if the bfqq have reqs are't complted. > > Thus I think bfq_del_bfqq_busy() is not the right place to do that. BTW, there is a counter 'dispatched' in bfqq, how about we rename it to 'inflight', and inc when adding req to bfqq, dec the same as 'dispatched' ? This way we can count bfqq when adding 'inflight' from 0 to 1, and stop when decreasing 'inflight' from 1 to 0.