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From: Kemeng Shi <shikemeng@huawei.com>
To: <tj@kernel.org>, <josef@toxicpanda.com>, <axboe@kernel.dk>
Cc: <cgroups@vger.kernel.org>, <linux-block@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>, <shikemeng@huawei.com>
Subject: [PATCH 03/11] blk-throttle: ignore cgroup without io queued in blk_throtl_cancel_bios
Date: Wed, 23 Nov 2022 14:03:53 +0800	[thread overview]
Message-ID: <20221123060401.20392-4-shikemeng@huawei.com> (raw)
In-Reply-To: <20221123060401.20392-1-shikemeng@huawei.com>

Ignore cgroup without io queued in blk_throtl_cancel_bios for two
reasons:
1. Save cpu cycle for trying to dispatch cgroup which is no io queued.
2. Avoid non-consistent state that cgroup is inserted to service queue
without THROTL_TG_PENDING set as tg_update_disptime will unconditional
re-insert cgroup to service queue. If we are on the default hierarchy,
IO dispatched from child in tg_dispatch_one_bio will trigger inserting
cgroup to service queue without erase first and ruin the tree.

Signed-off-by: Kemeng Shi <shikemeng@huawei.com>
---
 block/blk-throttle.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index b33bcf53b36e..acfac916ed99 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -1728,7 +1728,12 @@ void blk_throtl_cancel_bios(struct gendisk *disk)
 		 * Set the flag to make sure throtl_pending_timer_fn() won't
 		 * stop until all throttled bios are dispatched.
 		 */
-		blkg_to_tg(blkg)->flags |= THROTL_TG_CANCELING;
+		tg->flags |= THROTL_TG_CANCELING;
+
+		/* No need to dispatch cgroup without io queued */
+		if (!(tg->flags & THROTL_TG_PENDING))
+			continue;
+
 		/*
 		 * Update disptime after setting the above flag to make sure
 		 * throtl_select_dispatch() won't exit without dispatching.
-- 
2.30.0


WARNING: multiple messages have this Message-ID (diff)
From: Kemeng Shi <shikemeng-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
To: tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org,
	josef-DigfWCa+lFGyeJad7bwFQA@public.gmane.org,
	axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org
Cc: cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-block-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	shikemeng-hv44wF8Li93QT0dZR+AlfA@public.gmane.org
Subject: [PATCH 03/11] blk-throttle: ignore cgroup without io queued in blk_throtl_cancel_bios
Date: Wed, 23 Nov 2022 14:03:53 +0800	[thread overview]
Message-ID: <20221123060401.20392-4-shikemeng@huawei.com> (raw)
In-Reply-To: <20221123060401.20392-1-shikemeng-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>

Ignore cgroup without io queued in blk_throtl_cancel_bios for two
reasons:
1. Save cpu cycle for trying to dispatch cgroup which is no io queued.
2. Avoid non-consistent state that cgroup is inserted to service queue
without THROTL_TG_PENDING set as tg_update_disptime will unconditional
re-insert cgroup to service queue. If we are on the default hierarchy,
IO dispatched from child in tg_dispatch_one_bio will trigger inserting
cgroup to service queue without erase first and ruin the tree.

Signed-off-by: Kemeng Shi <shikemeng-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
---
 block/blk-throttle.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index b33bcf53b36e..acfac916ed99 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -1728,7 +1728,12 @@ void blk_throtl_cancel_bios(struct gendisk *disk)
 		 * Set the flag to make sure throtl_pending_timer_fn() won't
 		 * stop until all throttled bios are dispatched.
 		 */
-		blkg_to_tg(blkg)->flags |= THROTL_TG_CANCELING;
+		tg->flags |= THROTL_TG_CANCELING;
+
+		/* No need to dispatch cgroup without io queued */
+		if (!(tg->flags & THROTL_TG_PENDING))
+			continue;
+
 		/*
 		 * Update disptime after setting the above flag to make sure
 		 * throtl_select_dispatch() won't exit without dispatching.
-- 
2.30.0


  parent reply	other threads:[~2022-11-23  6:04 UTC|newest]

Thread overview: 61+ 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 ` 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  6:03   ` Kemeng Shi
2022-11-23 17:11   ` Tejun Heo
2022-11-24 11:47     ` Kemeng Shi
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  6:03   ` Kemeng Shi
2022-11-23 18:09   ` Tejun Heo
2022-11-23 18:09     ` Tejun Heo
2022-11-24 11:49     ` Kemeng Shi
2022-11-24 11:49       ` Kemeng Shi
2022-11-23  6:03 ` Kemeng Shi [this message]
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 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  6:03   ` Kemeng Shi
2022-11-23 18:18   ` Tejun Heo
2022-11-24 12:10     ` Kemeng Shi
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  6:03   ` Kemeng Shi
2022-11-23 18:26   ` Tejun Heo
2022-11-24 12:52     ` Kemeng Shi
2022-11-24 12:52       ` Kemeng Shi
2022-11-26  5:03   ` kernel test robot
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  6:03   ` Kemeng Shi
2022-11-23 18:26   ` Tejun Heo
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  6:03   ` Kemeng Shi
2022-11-23 18:27   ` Tejun Heo
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  6:03   ` Kemeng Shi
2022-11-23 18:28   ` Tejun Heo
2022-11-23 18:28     ` Tejun Heo
2022-11-24 12:58     ` Kemeng Shi
2022-11-24 12:58       ` Kemeng Shi
2022-11-26  8:15   ` kernel test robot
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  6:03   ` Kemeng Shi
2022-11-23 18:31   ` Tejun Heo
2022-11-23 18:31     ` Tejun Heo
2022-11-24 12:58     ` Kemeng Shi
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  6:04   ` Kemeng Shi
2022-11-23 18:30   ` Tejun Heo
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  6:04   ` Kemeng Shi
2022-11-23 18:29   ` Tejun Heo
2022-11-23 18:29     ` Tejun Heo
2022-11-24 13:02     ` Kemeng Shi
2022-11-24 13:02       ` Kemeng Shi

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