From patchwork Mon Mar 27 17:51:36 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Shaohua Li X-Patchwork-Id: 9647291 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 7990C6034B for ; Mon, 27 Mar 2017 17:54:06 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 698E028403 for ; Mon, 27 Mar 2017 17:54:06 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 57FA5283FB; Mon, 27 Mar 2017 17:54:06 +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=-7.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, RCVD_IN_DNSWL_HI autolearn=ham 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 DAE5228403 for ; Mon, 27 Mar 2017 17:54:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751564AbdC0Rx5 (ORCPT ); Mon, 27 Mar 2017 13:53:57 -0400 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:53646 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751294AbdC0RxV (ORCPT ); Mon, 27 Mar 2017 13:53:21 -0400 Received: from pps.filterd (m0089730.ppops.net [127.0.0.1]) by m0089730.ppops.net (8.16.0.20/8.16.0.20) with SMTP id v2RHhaL9023048 for ; Mon, 27 Mar 2017 10:51:48 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-type; s=facebook; bh=Y5x2PD+2XihwJ71INIFvec+TnsnriS3zXtVxrjzc/eI=; b=i6I9Ml3+2fHoqUTEGP5TtalrzYuRfn2Hfm69s5EHiM34JVC+waqUUQ8Z3/WOyHY5/Ip6 v+xNvUf/3oTSdxZKvK0043ZGKJZsbT4IgpHUgt/KxbN60gpt+aePRX2R8nEaOOYlJSnc Uff0qyL+KsqjvPlmzh08FdlfqAYJEemnv3M= Received: from mail.thefacebook.com ([199.201.64.23]) by m0089730.ppops.net with ESMTP id 29f66w0ar6-3 (version=TLSv1 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NOT) for ; Mon, 27 Mar 2017 10:51:48 -0700 Received: from mx-out.facebook.com (192.168.52.123) by PRN-CHUB02.TheFacebook.com (192.168.16.12) with Microsoft SMTP Server (TLS) id 14.3.319.2; Mon, 27 Mar 2017 10:51:47 -0700 Received: from facebook.com (2401:db00:21:603d:face:0:19:0) by mx-out.facebook.com (10.102.107.99) with ESMTP id 0be7d926131611e7a29c0002c99293a0-bc9fd9a0 for ; Mon, 27 Mar 2017 10:51:46 -0700 Received: by devbig638.prn2.facebook.com (Postfix, from userid 11222) id B1A7043A3BA3; Mon, 27 Mar 2017 10:51:46 -0700 (PDT) Smtp-Origin-Hostprefix: devbig From: Shaohua Li Smtp-Origin-Hostname: devbig638.prn2.facebook.com To: , CC: , , Vivek Goyal , , Smtp-Origin-Cluster: prn2c22 Subject: [PATCH V7 08/18] blk-throttle: make sure expire time isn't too big Date: Mon, 27 Mar 2017 10:51:36 -0700 Message-ID: <6bab8d46094d0076e9adda080d80c7ca0b9947f6.1490634565.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=2017-03-27_16:, , 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 throttled to a limit but when all cgroups cross high limit, queue enters a higher state and so the group should be throttled to a higher limit. It's possible the cgroup is sleeping because of throttle and other cgroups don't dispatch IO any more. In this case, nobody can trigger current downgrade/upgrade logic. To fix this issue, we could either set up a timer to wakeup the cgroup if other cgroups are idle or make sure this cgroup doesn't sleep too long. Setting up a timer means we must change the timer very frequently. This patch chooses the latter. Making cgroup sleep time not too big wouldn't change cgroup bps/iops, but could make it wakeup more frequently, which isn't a big issue because throtl_slice * 8 is already quite big. Signed-off-by: Shaohua Li --- block/blk-throttle.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 7878ec1..2073b48 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -590,6 +590,17 @@ static void throtl_dequeue_tg(struct throtl_grp *tg) static void throtl_schedule_pending_timer(struct throtl_service_queue *sq, unsigned long expires) { + unsigned long max_expire = jiffies + 8 * throtl_slice; + + /* + * Since we are adjusting the throttle limit dynamically, the sleep + * time calculated according to previous limit might be invalid. It's + * possible the cgroup sleep time is very long and no other cgroups + * have IO running so notify the limit changes. Make sure the cgroup + * doesn't sleep too long to avoid the missed notification. + */ + if (time_after(expires, max_expire)) + expires = max_expire; mod_timer(&sq->pending_timer, expires); throtl_log(sq, "schedule timer. delay=%lu jiffies=%lu", expires - jiffies, jiffies);