From: Tejun Heo <tj@kernel.org>
To: Kemeng Shi <shikemeng@huawei.com>
Cc: josef@toxicpanda.com, axboe@kernel.dk, cgroups@vger.kernel.org,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 04/11] blk-throttle: correct calculation of wait time in tg_may_dispatch
Date: Wed, 23 Nov 2022 08:18:56 -1000 [thread overview]
Message-ID: <Y35kELlFkI/BtkqC@slm.duckdns.org> (raw)
In-Reply-To: <20221123060401.20392-5-shikemeng@huawei.com>
On Wed, Nov 23, 2022 at 02:03:54PM +0800, Kemeng Shi wrote:
> If bps and iops both reach limit, we always return bps wait time as
> tg_within_iops_limit is after "tg_within_bps_limit(tg, bio, bps_limit) &&"
> and will not be called if tg_within_bps_limit return true.
Maybe it's obvious but it'd be better to explain "why" this change is being
made.
> @@ -939,8 +926,9 @@ static bool tg_may_dispatch(struct throtl_grp *tg, struct bio *bio,
> jiffies + tg->td->throtl_slice);
> }
>
> - if (tg_within_bps_limit(tg, bio, bps_limit, &bps_wait) &&
> - tg_within_iops_limit(tg, bio, iops_limit, &iops_wait)) {
> + bps_wait = tg_within_bps_limit(tg, bio, bps_limit);
> + iops_wait = tg_within_iops_limit(tg, bio, iops_limit);
> + if (bps_wait + iops_wait == 0) {
> if (wait)
> *wait = 0;
> return true;
So, max_wait is supposed to be maximum in the whole traversal path in the
tree, not just the max value in this tg, so after this, the code should be
changed to sth like the following, right?
max_wait = max(max, max(bps_wait, iops_wait));
Thanks.
--
tejun
next prev parent reply other threads:[~2022-11-23 18:19 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-23 6:03 [PATCH 00/11] A few bugfix and cleanup patches for blk-throttle Kemeng Shi
2022-11-23 6:03 ` [PATCH 01/11] blk-throttle: Limit whole system if root group is configured when on the default hierarchy Kemeng Shi
2022-11-23 17:11 ` Tejun Heo
2022-11-24 11:47 ` Kemeng Shi
2022-11-23 6:03 ` [PATCH 02/11] blk-throttle: Fix that bps of child could exceed bps limited in parent Kemeng Shi
2022-11-23 18:09 ` Tejun Heo
2022-11-24 11:49 ` Kemeng Shi
2022-11-23 6:03 ` [PATCH 03/11] blk-throttle: ignore cgroup without io queued in blk_throtl_cancel_bios Kemeng Shi
2022-11-23 18:13 ` Tejun Heo
2022-11-23 6:03 ` [PATCH 04/11] blk-throttle: correct calculation of wait time in tg_may_dispatch Kemeng Shi
2022-11-23 18:18 ` Tejun Heo [this message]
2022-11-24 12:10 ` Kemeng Shi
2022-11-23 6:03 ` [PATCH 05/11] blk-throttle: simpfy low limit reached check in throtl_tg_can_upgrade Kemeng Shi
2022-11-23 18:26 ` Tejun Heo
2022-11-24 12:52 ` Kemeng Shi
2022-11-26 5:03 ` kernel test robot
2022-11-23 6:03 ` [PATCH 06/11] blk-throttle: fix typo in comment of throtl_adjusted_limit Kemeng Shi
2022-11-23 18:26 ` Tejun Heo
2022-11-23 6:03 ` [PATCH 07/11] blk-throttle: remove incorrect comment for tg_last_low_overflow_time Kemeng Shi
2022-11-23 18:27 ` Tejun Heo
2022-11-23 6:03 ` [PATCH 08/11] blk-throttle: remove repeat check of elapsed time from last upgrade in throtl_hierarchy_can_downgrade Kemeng Shi
2022-11-23 18:28 ` Tejun Heo
2022-11-24 12:58 ` Kemeng Shi
2022-11-26 8:15 ` kernel test robot
2022-11-23 6:03 ` [PATCH 09/11] blk-throttle: remove unnecessary check for validation of limit index Kemeng Shi
2022-11-23 18:31 ` Tejun Heo
2022-11-24 12:58 ` Kemeng Shi
2022-11-23 6:04 ` [PATCH 10/11] blk-throttle: remove unused variable td in tg_update_has_rules Kemeng Shi
2022-11-23 18:30 ` Tejun Heo
2022-11-23 6:04 ` [PATCH 11/11] blk-throttle: Use more siutable time_after check for update slice_start Kemeng Shi
2022-11-23 18:29 ` Tejun Heo
2022-11-24 13:02 ` Kemeng Shi
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