From patchwork Wed Oct 13 11:25:34 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu Kuai X-Patchwork-Id: 12555651 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7C9EDC4332F for ; Wed, 13 Oct 2021 11:13:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 647B1601FC for ; Wed, 13 Oct 2021 11:13:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229571AbhJMLPJ (ORCPT ); Wed, 13 Oct 2021 07:15:09 -0400 Received: from szxga03-in.huawei.com ([45.249.212.189]:25181 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229653AbhJMLPI (ORCPT ); Wed, 13 Oct 2021 07:15:08 -0400 Received: from dggemv711-chm.china.huawei.com (unknown [172.30.72.53]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4HTqcC60wFz8tbx; Wed, 13 Oct 2021 19:11:55 +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 15.1.2308.8; Wed, 13 Oct 2021 19:13:01 +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 15.1.2308.8; Wed, 13 Oct 2021 19:13:01 +0800 From: Yu Kuai To: , CC: , , , Subject: [PATCH v3 2/2] block, bfq: do not idle if only one cgroup is activated Date: Wed, 13 Oct 2021 19:25:34 +0800 Message-ID: <20211013112534.3073296-3-yukuai3@huawei.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20211013112534.3073296-1-yukuai3@huawei.com> References: <20211013112534.3073296-1-yukuai3@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.175.127.227] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) 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. Test procedure: run "fio -numjobs=1 -ioengine=psync -bs=4k -direct=1 -rw=randread..." multiple times in the same cgroup. 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. This is because bfq_queue can be merged in this situation. 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 d251735383f7..8d94f511bee8 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 group 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 ; }