From patchwork Tue Nov 29 03:01:39 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kemeng Shi X-Patchwork-Id: 13058145 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 96F50C4332F for ; Tue, 29 Nov 2022 03:01:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235295AbiK2DBz (ORCPT ); Mon, 28 Nov 2022 22:01:55 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55928 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235290AbiK2DBy (ORCPT ); Mon, 28 Nov 2022 22:01:54 -0500 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7C77445084; Mon, 28 Nov 2022 19:01:53 -0800 (PST) Received: from kwepemi500016.china.huawei.com (unknown [172.30.72.53]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4NLnCs3z0Jz15Mxb; Tue, 29 Nov 2022 11:01:13 +0800 (CST) Received: from huawei.com (10.174.178.129) by kwepemi500016.china.huawei.com (7.221.188.220) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Tue, 29 Nov 2022 11:01:51 +0800 From: Kemeng Shi To: , , CC: , , , Subject: [PATCH v2 02/10] blk-throttle: Fix that bps of child could exceed bps limited in parent Date: Tue, 29 Nov 2022 11:01:39 +0800 Message-ID: <20221129030147.27400-3-shikemeng@huawei.com> X-Mailer: git-send-email 2.14.1.windows.1 In-Reply-To: <20221129030147.27400-1-shikemeng@huawei.com> References: <20221129030147.27400-1-shikemeng@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.174.178.129] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To kwepemi500016.china.huawei.com (7.221.188.220) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Consider situation as following (on the default hierarchy): HDD | root (bps limit: 4k) | child (bps limit :8k) | fio bs=8k Rate of fio is supposed to be 4k, but result is 8k. Reason is as following: Size of single IO from fio is larger than bytes allowed in one throtl_slice in child, so IOs are always queued in child group first. When queued IOs in child are dispatched to parent group, BIO_BPS_THROTTLED is set and these IOs will not be limited by tg_within_bps_limit anymore. Fix this by only set BIO_BPS_THROTTLED when the bio traversed the entire tree. There patch has no influence on situation which is not on the default hierarchy as each group is a single root group without parent. Signed-off-by: Kemeng Shi Acked-by: Tejun Heo --- block/blk-throttle.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 59acfac87764..d516a37e82fb 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -1067,7 +1067,6 @@ static void tg_dispatch_one_bio(struct throtl_grp *tg, bool rw) sq->nr_queued[rw]--; throtl_charge_bio(tg, bio); - bio_set_flag(bio, BIO_BPS_THROTTLED); /* * If our parent is another tg, we just need to transfer @bio to @@ -1080,6 +1079,7 @@ static void tg_dispatch_one_bio(struct throtl_grp *tg, bool rw) throtl_add_bio_tg(bio, &tg->qnode_on_parent[rw], parent_tg); start_parent_slice_with_credit(tg, parent_tg, rw); } else { + bio_set_flag(bio, BIO_BPS_THROTTLED); throtl_qnode_add_bio(bio, &tg->qnode_on_parent[rw], &parent_sq->queued[rw]); BUG_ON(tg->td->nr_queued[rw] <= 0);