From patchwork Tue May 17 13:49:09 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu Kuai X-Patchwork-Id: 12852512 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D803AC433FE for ; Tue, 17 May 2022 13:35:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347956AbiEQNfo (ORCPT ); Tue, 17 May 2022 09:35:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55844 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347907AbiEQNf2 (ORCPT ); Tue, 17 May 2022 09:35:28 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DE9AA4CD5F; Tue, 17 May 2022 06:35:26 -0700 (PDT) Received: from kwepemi100006.china.huawei.com (unknown [172.30.72.54]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4L2cY844NkzgYsy; Tue, 17 May 2022 21:34:36 +0800 (CST) Received: from kwepemm600009.china.huawei.com (7.193.23.164) by kwepemi100006.china.huawei.com (7.221.188.165) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Tue, 17 May 2022 21:35:24 +0800 Received: from huawei.com (10.175.127.227) by kwepemm600009.china.huawei.com (7.193.23.164) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Tue, 17 May 2022 21:35:23 +0800 From: Yu Kuai To: , , CC: , , , , Subject: [PATCH -next] blk-throttle: delay the setting of 'BIO_THROTTLED' to when throttle is done Date: Tue, 17 May 2022 21:49:09 +0800 Message-ID: <20220517134909.2910251-1-yukuai3@huawei.com> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 X-Originating-IP: [10.175.127.227] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To kwepemm600009.china.huawei.com (7.193.23.164) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org commit 9f5ede3c01f9 ("block: throttle split bio in case of iops limit") introduce a new problem, for example: [root@localhost ~]# echo "8:0 1024" > /sys/fs/cgroup/blkio/blkio.throttle.write_bps_device [root@localhost ~]# echo $$ > /sys/fs/cgroup/blkio/cgroup.procs [root@localhost ~]# dd if=/dev/zero of=/dev/sda bs=10k count=1 oflag=direct & [1] 620 [root@localhost ~]# dd if=/dev/zero of=/dev/sda bs=10k count=1 oflag=direct & [2] 626 [root@localhost ~]# 1+0 records in 1+0 records out 10240 bytes (10 kB, 10 KiB) copied, 10.0038 s, 1.0 kB/s1+0 records in 1+0 records out 10240 bytes (10 kB, 10 KiB) copied, 9.23076 s, 1.1 kB/s -> the second bio is issued after 10s instead of 20s. This is because if some bios are already queued, current bio is queued directly and the flag 'BIO_THROTTLED' is set. And later, when former bios are dispatched, this bio will be dispatched without waiting at all, this is due to tg_with_in_bps_limit() will return 0 if the flag is set. Instead of setting the flag when bio starts throttle, delay to when throttle is done to fix the problem. Fixes: 9f5ede3c01f9 ("block: throttle split bio in case of iops limit") Signed-off-by: Yu Kuai --- block/blk-throttle.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 447e1b8722f7..f952f2d942ff 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -811,7 +811,7 @@ static bool tg_with_in_bps_limit(struct throtl_grp *tg, struct bio *bio, unsigned int bio_size = throtl_bio_data_size(bio); /* no need to throttle if this bio's bytes have been accounted */ - if (bps_limit == U64_MAX || bio_flagged(bio, BIO_THROTTLED)) { + if (bps_limit == U64_MAX) { if (wait) *wait = 0; return true; @@ -1226,8 +1226,10 @@ static void blk_throtl_dispatch_work_fn(struct work_struct *work) spin_lock_irq(&q->queue_lock); for (rw = READ; rw <= WRITE; rw++) - while ((bio = throtl_pop_queued(&td_sq->queued[rw], NULL))) + while ((bio = throtl_pop_queued(&td_sq->queued[rw], NULL))) { + bio_set_flag(bio, BIO_THROTTLED); bio_list_add(&bio_list_on_stack, bio); + } spin_unlock_irq(&q->queue_lock); if (!bio_list_empty(&bio_list_on_stack)) { @@ -2134,7 +2136,8 @@ bool __blk_throtl_bio(struct bio *bio) } break; } - + /* this bio will be issued directly */ + bio_set_flag(bio, BIO_THROTTLED); /* within limits, let's charge and dispatch directly */ throtl_charge_bio(tg, bio); @@ -2190,7 +2193,6 @@ bool __blk_throtl_bio(struct bio *bio) out_unlock: spin_unlock_irq(&q->queue_lock); - bio_set_flag(bio, BIO_THROTTLED); #ifdef CONFIG_BLK_DEV_THROTTLING_LOW if (throttled || !td->track_bio_latency)