linux-kernel - [PATCH v3 8/9] blk-throttle: remove repeat check of elapsed time from last upgrade in throtl_hierarchy_can

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Message-Id: <20221205115709.251489-9-shikemeng@huaweicloud.com>
Date:   Mon,  5 Dec 2022 19:57:08 +0800
From:   Kemeng Shi <shikemeng@...weicloud.com>
To:     tj@...nel.org, josef@...icpanda.com, axboe@...nel.dk
Cc:     cgroups@...r.kernel.org, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org, shikemeng@...wei.com,
        linfeilong@...wei.com, liuzhiqiang26@...wei.com
Subject: [PATCH v3 8/9] blk-throttle: remove repeat check of elapsed time from last upgrade in throtl_hierarchy_can_downgrade

From: Kemeng Shi <shikemeng@...wei.com>

There is no need to check elapsed time from last upgrade for each node in
hierarchy. Move this check before traversing as throtl_can_upgrade do
to remove repeat check.

Signed-off-by: Kemeng Shi <shikemeng@...wei.com>
Reported-by: kernel test robot <lkp@...el.com>
Acked-by: Tejun Heo <tj@...nel.org>
Signed-off-by: Kemeng Shi <shikemeng@...weicloud.com>
---
 block/blk-throttle.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index e6a087de414d..413e668249cf 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -1955,8 +1955,7 @@ static bool throtl_tg_can_downgrade(struct throtl_grp *tg)
 	 * If cgroup is below low limit, consider downgrade and throttle other
 	 * cgroups
 	 */
-	if (time_after_eq(now, td->low_upgrade_time + td->throtl_slice) &&
-	    time_after_eq(now, tg_last_low_overflow_time(tg) +
+	if (time_after_eq(now, tg_last_low_overflow_time(tg) +
 					td->throtl_slice) &&
 	    (!throtl_tg_is_idle(tg) ||
 	     !list_empty(&tg_to_blkg(tg)->blkcg->css.children)))
@@ -1966,6 +1965,11 @@ static bool throtl_tg_can_downgrade(struct throtl_grp *tg)
 
 static bool throtl_hierarchy_can_downgrade(struct throtl_grp *tg)
 {
+	struct throtl_data *td = tg->td;
+
+	if (time_before(jiffies, td->low_upgrade_time + td->throtl_slice))
+		return false;
+
 	while (true) {
 		if (!throtl_tg_can_downgrade(tg))
 			return false;
-- 
2.30.0