From patchwork Sun Jan 15 03:42:35 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Shaohua Li X-Patchwork-Id: 9517227 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 8DECF60762 for ; Sun, 15 Jan 2017 03:43:10 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 82DFE20246 for ; Sun, 15 Jan 2017 03:43:10 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 775D025D99; Sun, 15 Jan 2017 03:43:10 +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=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 1B1C020246 for ; Sun, 15 Jan 2017 03:43:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750947AbdAODnI (ORCPT ); Sat, 14 Jan 2017 22:43:08 -0500 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:33969 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750937AbdAODmj (ORCPT ); Sat, 14 Jan 2017 22:42:39 -0500 Received: from pps.filterd (m0001255.ppops.net [127.0.0.1]) by mx0b-00082601.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v0F3gPY1005112 for ; Sat, 14 Jan 2017 19:42:38 -0800 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=QXo8PmDmDCrwYaTzlqCsk2JLbVDHmmXKC8UNp/bybVM=; b=rPwQdTfxGwPPJ1pUbFcklsOqMoIVyRg+KEGm9z7Dys/9FcYAQT6qztc/hrNrBfy7Qqeb JzloHt6qRg3l2YFcC2S0lBuRvgX9Ab9bmv5JIU++KItJCJKj4N/EDM0JRDDR0fKHZv3A UFKKbMgkwLldY/UhZMPdoRH8R1uaOElyVds= Received: from mail.thefacebook.com ([199.201.64.23]) by mx0b-00082601.pphosted.com with ESMTP id 27ygp5hj20-8 (version=TLSv1 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NOT) for ; Sat, 14 Jan 2017 19:42:38 -0800 Received: from mx-out.facebook.com (192.168.52.123) by PRN-CHUB04.TheFacebook.com (192.168.16.14) with Microsoft SMTP Server (TLS) id 14.3.294.0; Sat, 14 Jan 2017 19:42:36 -0800 Received: from facebook.com (2401:db00:21:603d:face:0:19:0) by mx-out.facebook.com (10.102.107.97) with ESMTP id a7ded174dad411e6ab8e0002c99331b0-dadf6a50 for ; Sat, 14 Jan 2017 19:42:36 -0800 Received: by devbig638.prn2.facebook.com (Postfix, from userid 11222) id 79F504363473; Sat, 14 Jan 2017 19:42:36 -0800 (PST) Smtp-Origin-Hostprefix: devbig From: Shaohua Li Smtp-Origin-Hostname: devbig638.prn2.facebook.com To: , CC: , , , Smtp-Origin-Cluster: prn2c22 Subject: [PATCH V6 18/18] blk-throttle: add latency target support Date: Sat, 14 Jan 2017 19:42:35 -0800 Message-ID: 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=2017-01-15_03:, , 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 One hard problem adding .low limit is to detect idle cgroup. If one cgroup doesn't dispatch enough IO against its low limit, we must have a mechanism to determine if other cgroups dispatch more IO. We added the think time detection mechanism before, but it doesn't work for all workloads. Here we add a latency based approach. We already have mechanism to calculate latency threshold for each IO size. For every IO dispatched from a cgorup, we compare its latency against its threshold and record the info. If most IO latency is below threshold (in the code I use 75%), the cgroup could be treated idle and other cgroups can dispatch more IO. Currently this latency target check is only for SSD as we can't calcualte the latency target for hard disk. And this is only for cgroup leaf node so far. Signed-off-by: Shaohua Li --- block/blk-throttle.c | 39 +++++++++++++++++++++++++++++++++++---- 1 file changed, 35 insertions(+), 4 deletions(-) diff --git a/block/blk-throttle.c b/block/blk-throttle.c index c0eb100..901af99 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -165,6 +165,10 @@ struct throtl_grp { unsigned long checked_last_finish_time; /* ns / 1024 */ unsigned long avg_idletime; /* ns / 1024 */ unsigned long idletime_threshold; /* us */ + + unsigned int bio_cnt; /* total bios */ + unsigned int bad_bio_cnt; /* bios exceeding latency threshold */ + unsigned long bio_cnt_reset_time; }; /* We measure latency for request size from <= 4k to >= 1M */ @@ -1720,12 +1724,15 @@ static bool throtl_tg_is_idle(struct throtl_grp *tg) * - single idle is too long, longer than a fixed value (in case user * configure a too big threshold) or 4 times of slice * - average think time is more than threshold + * - IO latency is largely below threshold */ unsigned long time = jiffies_to_usecs(4 * tg->td->throtl_slice); time = min_t(unsigned long, MAX_IDLE_TIME, time); return (ktime_get_ns() >> 10) - tg->last_finish_time > time || - tg->avg_idletime > tg->idletime_threshold; + tg->avg_idletime > tg->idletime_threshold || + (tg->latency_target && tg->bio_cnt && + tg->bad_bio_cnt * 5 < tg->bio_cnt); } static bool throtl_tg_can_upgrade(struct throtl_grp *tg) @@ -2185,11 +2192,35 @@ void blk_throtl_bio_endio(struct bio *bio) start_time = blk_stat_time(&bio->bi_issue_stat) >> 10; finish_time = __blk_stat_time(finish_time_ns) >> 10; - if (start_time && finish_time > start_time && - !(bio->bi_issue_stat.stat & SKIP_LATENCY)) { - lat = finish_time - start_time; + if (!start_time || finish_time <= start_time) + return; + + lat = finish_time - start_time; + if (!(bio->bi_issue_stat.stat & SKIP_LATENCY)) throtl_track_latency(tg->td, blk_stat_size(&bio->bi_issue_stat), bio_op(bio), lat); + + if (tg->latency_target) { + int bucket; + unsigned int threshold; + + bucket = request_bucket_index( + blk_stat_size(&bio->bi_issue_stat)); + threshold = tg->td->avg_buckets[bucket].latency + + tg->latency_target; + if (lat > threshold) + tg->bad_bio_cnt++; + /* + * Not race free, could get wrong count, which means cgroups + * will be throttled + */ + tg->bio_cnt++; + } + + if (time_after(jiffies, tg->bio_cnt_reset_time) || tg->bio_cnt > 1024) { + tg->bio_cnt_reset_time = tg->td->throtl_slice + jiffies; + tg->bio_cnt /= 2; + tg->bad_bio_cnt /= 2; } }