From patchwork Wed Aug 16 01:27:06 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu Kuai X-Patchwork-Id: 13354475 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 0E700C001B0 for ; Wed, 16 Aug 2023 01:31:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241058AbjHPBa5 (ORCPT ); Tue, 15 Aug 2023 21:30:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46752 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241115AbjHPBay (ORCPT ); Tue, 15 Aug 2023 21:30:54 -0400 Received: from dggsgout11.his.huawei.com (unknown [45.249.212.51]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 286C42121; Tue, 15 Aug 2023 18:30:53 -0700 (PDT) Received: from mail02.huawei.com (unknown [172.30.67.169]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4RQVvY6Zh1z4f3q3b; Wed, 16 Aug 2023 09:30:49 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.104.67]) by APP4 (Coremail) with SMTP id gCh0CgAH5KbHJtxkQuVAAw--.55976S6; Wed, 16 Aug 2023 09:30:50 +0800 (CST) From: Yu Kuai To: tj@kernel.org, josef@toxicpanda.com, axboe@kernel.dk, yukuai3@huawei.com, mkoutny@suse.com Cc: cgroups@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, yukuai1@huaweicloud.com, yi.zhang@huawei.com, yangerkun@huawei.com Subject: [PATCH -next v2 2/4] blk-throttle: fix wrong comparation while 'carryover_ios/bytes' is negative Date: Wed, 16 Aug 2023 09:27:06 +0800 Message-Id: <20230816012708.1193747-3-yukuai1@huaweicloud.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230816012708.1193747-1-yukuai1@huaweicloud.com> References: <20230816012708.1193747-1-yukuai1@huaweicloud.com> MIME-Version: 1.0 X-CM-TRANSID: gCh0CgAH5KbHJtxkQuVAAw--.55976S6 X-Coremail-Antispam: 1UD129KBjvJXoWxAFWkAF4xAry8WF17KF17ZFb_yoW5ArWrpr WfGF1IgF4rX3Z3tFnxJan8AFyrt39rAr98GrW3WayrCFn8GFyktrn5uFWFyayUZFs3uF4S kw1FqFn7AF4qyaDanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUBK14x267AKxVWrJVCq3wAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_Jryl82xGYIkIc2 x26xkF7I0E14v26ryj6s0DM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2z4x0 Y4vE2Ix0cI8IcVAFwI0_Xr0_Ar1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Cr0_Gr1UM2 8EF7xvwVC2z280aVAFwI0_GcCE3s1l84ACjcxK6I8E87Iv6xkF7I0E14v26rxl6s0DM2AI xVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40Ex7xfMcIj6xIIjxv20x vE14v26r1j6r18McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x0Yz7v_Jr0_Gr1lF7xv r2IYc2Ij64vIr41lF7I21c0EjII2zVCS5cI20VAGYxC7M4IIrI8v6xkF7I0E8cxan2IY04 v7MxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_ Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVWUtVW8ZwCIc40Y0x 0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AKxVW8 JVWxJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Jr0_Gr1lIx AIcVC2z280aVCY1x0267AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZEXa7VUbdOz7UUUUU= = X-CM-SenderInfo: 51xn3trlr6x35dzhxuhorxvhhfrp/ X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org From: Yu Kuai carryover_ios/bytes[] can be negative in the case that ios are dispatched in the slice in advance, and then configuration is updated. For example: 1) set iops limit to 1000, and slice start is 0, slice end is 100ms; 2) current time is 0, and 100 ios are dispatched, those ios will not be throttled, hence io_disp is 100; 3) still at current time 0, update iops limit to 100, then carryover_ios is (0 - 100) = -100; 4) then, dispatch a new io at time 0, the expected result is that this io will wait for 1s. The calculation in tg_within_iops_limit: io_disp = 0; io_allowed = calculate_io_allowed + carryover_ios = 10 + (-100) = -90; io won't be throttled if (io_disp + 1 < io_allowed) passed. Before this patch, in step 4) (io_disp + 1 < io_allowed) is passed, because -90 for unsigned value is very huge, and such io won't be throttled. Fix this problem by checking if 'io/bytes_allowed' is negative first. Signed-off-by: Yu Kuai Acked-by: Tejun Heo --- block/blk-throttle.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 5184f17f5129..7c93144d03da 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -825,7 +825,7 @@ static unsigned long tg_within_iops_limit(struct throtl_grp *tg, struct bio *bio u32 iops_limit) { bool rw = bio_data_dir(bio); - unsigned int io_allowed; + int io_allowed; unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd; if (iops_limit == UINT_MAX) { @@ -838,9 +838,8 @@ static unsigned long tg_within_iops_limit(struct throtl_grp *tg, struct bio *bio jiffy_elapsed_rnd = roundup(jiffy_elapsed + 1, tg->td->throtl_slice); io_allowed = calculate_io_allowed(iops_limit, jiffy_elapsed_rnd) + tg->carryover_ios[rw]; - if (tg->io_disp[rw] + 1 <= io_allowed) { + if (io_allowed > 0 && tg->io_disp[rw] + 1 <= io_allowed) return 0; - } /* Calc approx time to dispatch */ jiffy_wait = jiffy_elapsed_rnd - jiffy_elapsed; @@ -851,7 +850,8 @@ static unsigned long tg_within_bps_limit(struct throtl_grp *tg, struct bio *bio, u64 bps_limit) { bool rw = bio_data_dir(bio); - u64 bytes_allowed, extra_bytes; + long long bytes_allowed; + u64 extra_bytes; unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd; unsigned int bio_size = throtl_bio_data_size(bio); @@ -869,9 +869,8 @@ static unsigned long tg_within_bps_limit(struct throtl_grp *tg, struct bio *bio, jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, tg->td->throtl_slice); bytes_allowed = calculate_bytes_allowed(bps_limit, jiffy_elapsed_rnd) + tg->carryover_bytes[rw]; - if (tg->bytes_disp[rw] + bio_size <= bytes_allowed) { + if (bytes_allowed > 0 && tg->bytes_disp[rw] + bio_size <= bytes_allowed) return 0; - } /* Calc approx time to dispatch */ extra_bytes = tg->bytes_disp[rw] + bio_size - bytes_allowed;