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=-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=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 392F7C432BE for ; Fri, 6 Aug 2021 01:57:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1D0C861186 for ; Fri, 6 Aug 2021 01:57:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243318AbhHFB6C (ORCPT ); Thu, 5 Aug 2021 21:58:02 -0400 Received: from szxga02-in.huawei.com ([45.249.212.188]:12459 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232728AbhHFB54 (ORCPT ); Thu, 5 Aug 2021 21:57:56 -0400 Received: from dggemv703-chm.china.huawei.com (unknown [172.30.72.53]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4GgpRx1bfBzckl9; Fri, 6 Aug 2021 09:54:05 +0800 (CST) Received: from dggema762-chm.china.huawei.com (10.1.198.204) by dggemv703-chm.china.huawei.com (10.3.19.46) 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 09:57:40 +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 09:57:39 +0800 From: Yu Kuai To: , CC: , , , Subject: [PATCH v2 4/4] block, bfq: consider request size in bfq_asymmetric_scenario() Date: Fri, 6 Aug 2021 10:08:26 +0800 Message-ID: <20210806020826.1407257-5-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 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII 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-kernel@vger.kernel.org There is a special case when bfq do not need to idle when more than one groups is active: 1) all active queues have the same weight, 2) all active queues have the same request size. 3) all active queues belong to the same I/O-priority class, Each time a request is dispatched, bfq can switch in service queue safely, since the throughput of each active queue is guaranteed to be equivalent. Test procedure: run "fio -numjobs=1 -ioengine=psync -bs=4k -direct=1 -rw=randread..." in different 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) | Signed-off-by: Yu Kuai --- block/bfq-iosched.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 7df3fc0ef4ef..e5a07bd1fd84 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -268,6 +268,16 @@ static struct kmem_cache *bfq_pool; */ #define BFQ_RATE_SHIFT 16 +/* + * 1) bfq keep dispatching requests with same size for at least one second. + * 2) bfq dispatch at lease 1024 requests + * + * We think bfq are dispatching request with same size if the above two + * conditions hold true. + */ +#define VARIED_REQUEST_SIZE(bfqd) ((bfqd)->dispatch_count < 1024 ||\ + time_before(jiffies, (bfqd)->dispatch_time + HZ)) + /* * When configured for computing the duration of the weight-raising * for interactive queues automatically (see the comments at the @@ -724,7 +734,8 @@ static bool bfq_asymmetric_scenario(struct bfq_data *bfqd, bool multiple_classes_busy; #ifdef CONFIG_BFQ_GROUP_IOSCHED - if (bfqd->num_groups_with_pending_reqs > 1) + if (bfqd->num_groups_with_pending_reqs > 1 && + VARIED_REQUEST_SIZE(bfqd)) return true; if (bfqd->num_groups_with_pending_reqs && -- 2.31.1