From patchwork Mon Oct 3 21:20:27 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Shaohua Li X-Patchwork-Id: 9360977 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 69D54608A6 for ; Mon, 3 Oct 2016 21:23:24 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5F55E28A69 for ; Mon, 3 Oct 2016 21:23:24 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 53C2428A74; Mon, 3 Oct 2016 21:23:24 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,T_DKIM_INVALID autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C4A9E28A6E for ; Mon, 3 Oct 2016 21:23:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752378AbcJCVXR (ORCPT ); Mon, 3 Oct 2016 17:23:17 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:55965 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752134AbcJCVUg (ORCPT ); Mon, 3 Oct 2016 17:20:36 -0400 Received: from pps.filterd (m0044008.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.17/8.16.0.17) with SMTP id u93LIOkG001970 for ; Mon, 3 Oct 2016 14:20:35 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=fb.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-type; s=facebook; bh=PIlwwqDYgFYzuH7KFcnKtmME18oD5W7+alkLooNhX5w=; b=oV/8S/25Pf6ILx2xEwd/WXOYcvYqZe2s3lpjNGcMw46trU5p8ZU3P0qibtkx9T8rDQe+ eRTFeJg7M0Qb5JgylTBMX6nF5mmmY4XS/EyNuTHVDVfDLHwuhZybO8hlHrcVu1B4ERig E6yx5vpQZj34zFm8UE08cBTKtNNCrMd1hTI= Received: from mail.thefacebook.com ([199.201.64.23]) by mx0a-00082601.pphosted.com with ESMTP id 25uvb51hw3-7 (version=TLSv1 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NOT) for ; Mon, 03 Oct 2016 14:20:35 -0700 Received: from mx-out.facebook.com (192.168.52.123) by PRN-CHUB09.TheFacebook.com (192.168.16.19) with Microsoft SMTP Server (TLS) id 14.3.294.0; Mon, 3 Oct 2016 14:20:34 -0700 Received: from facebook.com (2401:db00:21:603d:face:0:19:0) by mx-out.facebook.com (10.223.100.97) with ESMTP id 37fc744a89af11e69e6224be0593f280-6eae7a50 for ; Mon, 03 Oct 2016 14:20:33 -0700 Received: by devbig638.prn2.facebook.com (Postfix, from userid 11222) id 7FA4D42C11AA; Mon, 3 Oct 2016 14:20:31 -0700 (PDT) From: Shaohua Li To: , CC: , , , , Subject: [PATCH v3 08/11] blk-throttle: detect completed idle cgroup Date: Mon, 3 Oct 2016 14:20:27 -0700 Message-ID: <12dcc0dec825f25b5c8198d03b3c5d4e646724c8.1475529372.git.shli@fb.com> X-Mailer: git-send-email 2.9.3 In-Reply-To: References: X-FB-Internal: Safe MIME-Version: 1.0 X-Proofpoint-Spam-Reason: safe X-FB-Internal: Safe X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2016-10-03_12:, , signatures=0 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP cgroup could be assigned a limit, but doesn't dispatch enough IO, eg the cgroup is idle. When this happens, the cgroup doesn't hit its limit, so we can't move the state machine to higher level and all cgroups will be throttled to thier lower limit, so we waste bandwidth. Detecting idle cgroup is hard. This patch handles a simple case, a cgroup doesn't dispatch any IO. We ignore such cgroup's limit, so other cgroups can use the bandwidth. Signed-off-by: Shaohua Li --- block/blk-throttle.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 4263f0c..759bce1 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -144,6 +144,8 @@ struct throtl_grp { unsigned long last_check_time; + unsigned long last_dispatch_time[2]; + /* When did we start a new slice */ unsigned long slice_start[2]; unsigned long slice_end[2]; @@ -438,11 +440,14 @@ static void tg_update_has_rules(struct throtl_grp *tg) static void throtl_pd_online(struct blkg_policy_data *pd) { + struct throtl_grp *tg = pd_to_tg(pd); /* * We don't want new groups to escape the limits of its ancestors. * Update has_rules[] after a new group is brought online. */ - tg_update_has_rules(pd_to_tg(pd)); + tg_update_has_rules(tg); + tg->last_dispatch_time[READ] = jiffies; + tg->last_dispatch_time[WRITE] = jiffies; } static void blk_throtl_update_valid_limit(struct throtl_data *td) @@ -1606,6 +1611,12 @@ static bool throtl_upgrade_check_one(struct throtl_grp *tg) if (write_limit && sq->nr_queued[WRITE] && (!read_limit || sq->nr_queued[READ])) return true; + + if (time_after_eq(jiffies, + tg->last_dispatch_time[READ] + tg->td->throtl_slice) && + time_after_eq(jiffies, + tg->last_dispatch_time[WRITE] + tg->td->throtl_slice)) + return true; return false; } @@ -1686,6 +1697,9 @@ static bool throtl_downgrade_check_one(struct throtl_grp *tg) struct throtl_data *td = tg->td; unsigned long now = jiffies; + if (time_after_eq(now, tg->last_dispatch_time[READ] + td->throtl_slice) && + time_after_eq(now, tg->last_dispatch_time[WRITE] + td->throtl_slice)) + return false; /* * If cgroup is below high limit, consider downgrade and throttle other * cgroups @@ -1804,6 +1818,7 @@ bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg, again: while (true) { + tg->last_dispatch_time[rw] = jiffies; if (tg->last_high_overflow_time[rw] == 0) tg->last_high_overflow_time[rw] = jiffies; throtl_downgrade_check(tg);