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=-17.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 BBF5BC432BE for ; Thu, 2 Sep 2021 13:23:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 99C5D60F42 for ; Thu, 2 Sep 2021 13:23:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345094AbhIBNYO (ORCPT ); Thu, 2 Sep 2021 09:24:14 -0400 Received: from szxga01-in.huawei.com ([45.249.212.187]:19004 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345038AbhIBNYK (ORCPT ); Thu, 2 Sep 2021 09:24:10 -0400 Received: from dggemv704-chm.china.huawei.com (unknown [172.30.72.55]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4H0hN02rV2zbl2R; Thu, 2 Sep 2021 21:19:12 +0800 (CST) Received: from dggema762-chm.china.huawei.com (10.1.198.204) by dggemv704-chm.china.huawei.com (10.3.19.47) 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 21:23:08 +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 21:23:08 +0800 Subject: Re: [PATCH v2 1/4] block, bfq: add support to track if root_group have any pending requests To: Paolo Valente CC: , , , References: <20210806020826.1407257-1-yukuai3@huawei.com> <20210806020826.1407257-2-yukuai3@huawei.com> <2968B663-F855-4C41-AE9B-E33787DA6AF9@linaro.org> From: "yukuai (C)" Message-ID: <7ee856f6-ca13-67dc-d2db-d73ef31ffdd9@huawei.com> Date: Thu, 2 Sep 2021 21:23:07 +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: <2968B663-F855-4C41-AE9B-E33787DA6AF9@linaro.org> Content-Type: text/plain; charset="gbk"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.176.73] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To dggema762-chm.china.huawei.com (10.1.198.204) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/08/27 1:00, Paolo Valente wrote: > > >> Il giorno 6 ago 2021, alle ore 04:08, Yu Kuai ha scritto: >> >> Add a new member in bfq_data to track number of queues that are in >> root_group with any pending requests. > > maybe modify the last part of the sentence as: ... and that have some pending request > >> This will be used in next patch >> to optmize queue idle judgment when root_group doesn't have any >> pending requests. >> >> Signed-off-by: Yu Kuai >> --- >> block/bfq-iosched.c | 8 +++++++- >> block/bfq-iosched.h | 13 +++++++++++-- >> block/bfq-wf2q.c | 37 ++++++++++++++++++++++++------------- >> 3 files changed, 42 insertions(+), 16 deletions(-) >> >> diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c >> index 727955918563..7c6b412f9a9c 100644 >> --- a/block/bfq-iosched.c >> +++ b/block/bfq-iosched.c >> @@ -859,8 +859,14 @@ void __bfq_weights_tree_remove(struct bfq_data *bfqd, >> void bfq_weights_tree_remove(struct bfq_data *bfqd, >> struct bfq_queue *bfqq) >> { >> - struct bfq_entity *entity = bfqq->entity.parent; >> + struct bfq_entity *entity = &bfqq->entity; >> + >> + if (entity->in_groups_with_pending_reqs) { >> + entity->in_groups_with_pending_reqs = false; >> + bfqd->num_queues_with_pending_reqs_in_root--; > > Here you cross the comment "The decrement of > num_groups_with_pending_reqs is not performed immediately upon ...". > > Find a way to > - move that comment up, and to make it correct for this slightly > different decrement > - leave a correct comment (probably shorter) in the original position > >> + } >> >> + entity = entity->parent; >> for_each_entity(entity) { >> struct bfq_sched_data *sd = entity->my_sched_data; >> >> diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h >> index 99c2a3cb081e..610769214f72 100644 >> --- a/block/bfq-iosched.h >> +++ b/block/bfq-iosched.h >> @@ -195,7 +195,12 @@ struct bfq_entity { >> /* flag, set to request a weight, ioprio or ioprio_class change */ >> int prio_changed; >> >> - /* flag, set if the entity is counted in groups_with_pending_reqs */ >> + /* >> + * If entity represents bfq_group, this flag will set > > will be set? > >> if the group is >> + * not root_group and have > > has > >> any pending requests; If entity represents > > one more nit: use lowercase after semicolon > >> + * bfq_queue, this flag will set > > will be set > >> if the queue is in root_group and have >> + * any pending requests. >> + */ >> bool in_groups_with_pending_reqs; >> > > The name of the above field follows from the fact that entity is > counted in groups_with_pending_reqs. You change this fact, because, > in your patch, a queue is not counted in groups_with_pending_reqs. > But you leave the same name. This creates confusion. > > >> /* last child queue of entity created (for non-leaf entities) */ >> @@ -539,7 +544,11 @@ struct bfq_data { >> * with no request waiting for completion. >> */ >> unsigned int num_groups_with_pending_reqs; >> - >> + /* >> + * number of queues that are in root_group with at least one request >> + * waiting for completion. > > please link somehow this comment to the long comment that comes before it > >> + */ >> + unsigned int num_queues_with_pending_reqs_in_root; > > Why using two counters? I mean, couldn't you simply count also the > root group in num_groups_with_pending_reqs? Hi, Paolo Thanks for taking time reviewing these patches I was doing this too complicated, while counting root group into num_groups_with_pending_reqs is much easier. I'll do this in next iteration. Thanks Yu Kuai > >> /* >> * Per-class (RT, BE, IDLE) number of bfq_queues containing >> * requests (including the queue in service, even if it is >> diff --git a/block/bfq-wf2q.c b/block/bfq-wf2q.c >> index 7a462df71f68..188c8f907219 100644 >> --- a/block/bfq-wf2q.c >> +++ b/block/bfq-wf2q.c >> @@ -946,6 +946,29 @@ static void bfq_update_fin_time_enqueue(struct bfq_entity *entity, >> bfq_active_insert(st, entity); >> } >> >> +static void bfq_update_groups_with_pending_reqs(struct bfq_entity *entity) >> +{ >> +#ifdef CONFIG_BFQ_GROUP_IOSCHED >> + struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); >> + > > why do you introduce an extra variable bfqq, instead of doing as in > the original version of the code? In addition, you remove the comment > /* bfq_group */ > > Thanks, > Paolo > >> + if (bfqq) { >> + if (!entity->parent && !entity->in_groups_with_pending_reqs) { >> + entity->in_groups_with_pending_reqs = true; >> + bfqq->bfqd->num_queues_with_pending_reqs_in_root++; >> + } >> + } else { >> + if (!entity->in_groups_with_pending_reqs) { >> + struct bfq_group *bfqg = >> + container_of(entity, struct bfq_group, entity); >> + struct bfq_data *bfqd = bfqg->bfqd; >> + >> + entity->in_groups_with_pending_reqs = true; >> + bfqd->num_groups_with_pending_reqs++; >> + } >> + } >> +#endif >> +} >> + >> /** >> * __bfq_activate_entity - handle activation of entity. >> * @entity: the entity being activated. >> @@ -999,19 +1022,7 @@ static void __bfq_activate_entity(struct bfq_entity *entity, >> entity->on_st_or_in_serv = true; >> } >> >> -#ifdef CONFIG_BFQ_GROUP_IOSCHED >> - if (!bfq_entity_to_bfqq(entity)) { /* bfq_group */ >> - struct bfq_group *bfqg = >> - container_of(entity, struct bfq_group, entity); >> - struct bfq_data *bfqd = bfqg->bfqd; >> - >> - if (!entity->in_groups_with_pending_reqs) { >> - entity->in_groups_with_pending_reqs = true; >> - bfqd->num_groups_with_pending_reqs++; >> - } >> - } >> -#endif >> - >> + bfq_update_groups_with_pending_reqs(entity); >> bfq_update_fin_time_enqueue(entity, st, backshifted); >> } >> >> -- >> 2.31.1 >> > > . >