From patchwork Sat Nov 27 10:11:28 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu Kuai X-Patchwork-Id: 12642195 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 DCCA2C433EF for ; Sat, 27 Nov 2021 10:01:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1354101AbhK0KEt (ORCPT ); Sat, 27 Nov 2021 05:04:49 -0500 Received: from szxga03-in.huawei.com ([45.249.212.189]:28183 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1354061AbhK0KCl (ORCPT ); Sat, 27 Nov 2021 05:02:41 -0500 Received: from dggemv704-chm.china.huawei.com (unknown [172.30.72.55]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4J1Rqb1NrDz8vfs; Sat, 27 Nov 2021 17:57:31 +0800 (CST) Received: from kwepemm600009.china.huawei.com (7.193.23.164) by dggemv704-chm.china.huawei.com (10.3.19.47) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.20; Sat, 27 Nov 2021 17:59:25 +0800 Received: from huawei.com (10.175.127.227) 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 15.1.2308.20; Sat, 27 Nov 2021 17:59:24 +0800 From: Yu Kuai To: , , CC: , , , , Subject: [PATCH RFC 5/9] block, bfq: do not idle if only one cgroup is activated Date: Sat, 27 Nov 2021 18:11:28 +0800 Message-ID: <20211127101132.486806-6-yukuai3@huawei.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20211127101132.486806-1-yukuai3@huawei.com> References: <20211127101132.486806-1-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 kwepemm600009.china.huawei.com (7.193.23.164) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Now that root group is counted into 'num_groups_with_pending_reqs', 'num_groups_with_pending_reqs > 0' is always true in bfq_asymmetric_scenario(). If only one group is activated, there is no need to guarantee the same share of the throughput of queues in the same group. Thus change the condition to 'num_groups_with_pending_reqs > 1'. Signed-off-by: Yu Kuai --- block/bfq-iosched.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 47722f931ee3..63e4e13db92f 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -709,7 +709,7 @@ 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 groups at most. * 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. @@ -741,7 +741,7 @@ static bool bfq_asymmetric_scenario(struct bfq_data *bfqd, return varied_queue_weights || multiple_classes_busy #ifdef CONFIG_BFQ_GROUP_IOSCHED - || bfqd->num_groups_with_pending_reqs > 0 + || bfqd->num_groups_with_pending_reqs > 1 #endif ; }