From patchwork Fri Aug 6 02:08:24 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu Kuai X-Patchwork-Id: 12422539 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 DF2BCC4320E for ; Fri, 6 Aug 2021 01:57:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B501460C51 for ; Fri, 6 Aug 2021 01:57:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231893AbhHFB56 (ORCPT ); Thu, 5 Aug 2021 21:57:58 -0400 Received: from szxga01-in.huawei.com ([45.249.212.187]:7795 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231993AbhHFB54 (ORCPT ); Thu, 5 Aug 2021 21:57:56 -0400 Received: from dggemv711-chm.china.huawei.com (unknown [172.30.72.55]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4GgpWv6c3LzYlXr; Fri, 6 Aug 2021 09:57:31 +0800 (CST) Received: from dggema762-chm.china.huawei.com (10.1.198.204) by dggemv711-chm.china.huawei.com (10.1.198.66) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2176.2; Fri, 6 Aug 2021 09:57:39 +0800 Received: from huawei.com (10.175.127.227) 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 15.1.2176.2; Fri, 6 Aug 2021 09:57:38 +0800 From: Yu Kuai To: , CC: , , , Subject: [PATCH v2 2/4] block, bfq: do not idle if only one cgroup is activated Date: Fri, 6 Aug 2021 10:08:24 +0800 Message-ID: <20210806020826.1407257-3-yukuai3@huawei.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210806020826.1407257-1-yukuai3@huawei.com> References: <20210806020826.1407257-1-yukuai3@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.175.127.227] 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-block@vger.kernel.org If only one group is activated, there is no need to guarantee the same share of the throughput of queues in the same group. If CONFIG_BFQ_GROUP_IOSCHED is enabled, there is no need to check 'varied_queue_weights' and 'multiple_classes_busy': 1) num_groups_with_pending_reqs = 0, idle is not needed 2) num_groups_with_pending_reqs = 1 - if root group have any pending requests, idle is needed - if root group is idle, idle is not needed 3) num_groups_with_pending_reqs > 1, idle is needed Test procedure: run "fio -numjobs=1 -ioengine=psync -bs=4k -direct=1 -rw=randread..." multiple times in the same cgroup(not root). Test result: total bandwidth(Mib/s) | total jobs | before this patch | after this patch | | ---------- | ----------------- | --------------------- | | 1 | 33.8 | 33.8 | | 2 | 33.8 | 65.4 (32.7 each job) | | 4 | 33.8 | 106.8 (26.7 each job) | | 8 | 33.8 | 126.4 (15.8 each job) | By the way, if I test with "fio -numjobs=1/2/4/8 ...", test result is the same with or without this patch. Signed-off-by: Yu Kuai --- block/bfq-iosched.c | 35 ++++++++++++++++++++++++++--------- 1 file changed, 26 insertions(+), 9 deletions(-) diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 7c6b412f9a9c..a780205a1be4 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -709,7 +709,9 @@ bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq) * much easier to maintain the needed state: * 1) all active queues have the same weight, * 2) all active queues belong to the same I/O-priority class, - * 3) there are no active groups. + * 3) there are one active group at most(incluing root_group). + * If the last condition is false, there is no need to guarantee the, + * same share of the throughput of queues in the same group. * In particular, the last condition is always true if hierarchical * support or the cgroups interface are not enabled, thus no state * needs to be maintained in this case. @@ -717,7 +719,26 @@ bfq_pos_tree_add_move(struct bfq_data *bfqd, struct bfq_queue *bfqq) static bool bfq_asymmetric_scenario(struct bfq_data *bfqd, struct bfq_queue *bfqq) { - bool smallest_weight = bfqq && + bool smallest_weight; + bool varied_queue_weights; + bool multiple_classes_busy; + +#ifdef CONFIG_BFQ_GROUP_IOSCHED + if (bfqd->num_groups_with_pending_reqs > 1) + return true; + + if (bfqd->num_groups_with_pending_reqs && + bfqd->num_queues_with_pending_reqs_in_root) + return true; + + /* + * Reach here means only one group(incluing root group) has pending + * requests, thus it's safe to return. + */ + return false; +#endif + + smallest_weight = bfqq && bfqq->weight_counter && bfqq->weight_counter == container_of( @@ -729,21 +750,17 @@ static bool bfq_asymmetric_scenario(struct bfq_data *bfqd, * For queue weights to differ, queue_weights_tree must contain * at least two nodes. */ - bool varied_queue_weights = !smallest_weight && + varied_queue_weights = !smallest_weight && !RB_EMPTY_ROOT(&bfqd->queue_weights_tree.rb_root) && (bfqd->queue_weights_tree.rb_root.rb_node->rb_left || bfqd->queue_weights_tree.rb_root.rb_node->rb_right); - bool multiple_classes_busy = + multiple_classes_busy = (bfqd->busy_queues[0] && bfqd->busy_queues[1]) || (bfqd->busy_queues[0] && bfqd->busy_queues[2]) || (bfqd->busy_queues[1] && bfqd->busy_queues[2]); - return varied_queue_weights || multiple_classes_busy -#ifdef CONFIG_BFQ_GROUP_IOSCHED - || bfqd->num_groups_with_pending_reqs > 0 -#endif - ; + return varied_queue_weights || multiple_classes_busy; } /*