From acaf523a7bf226b28504306c1cfee194520123b3 Mon Sep 17 00:00:00 2001
From: Yu Kuai <yukuai3@huawei.com>
Date: Thu, 26 Nov 2020 11:18:34 +0800
Subject: [PATCH] blk-throttle: don't check whether or not lower limit is valid
if CONFIG_BLK_DEV_THROTTLING_LOW is off
blk_throtl_update_limit_valid() will search for descendants to see if
'LIMIT_LOW' of bps/iops and READ/WRITE is nonzero. However, they're always
zero if CONFIG_BLK_DEV_THROTTLING_LOW is not set, furthermore, a lot of
time will be wasted to iterate descendants.
Thus do nothing in blk_throtl_update_limit_valid() in such situation.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
block/blk-throttle.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index b771c42999827..d52cac9f3a7c2 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -587,6 +587,7 @@ static void throtl_pd_online(struct blkg_policy_data *pd)
tg_update_has_rules(tg);
}
+#ifdef CONFIG_BLK_DEV_THROTTLING_LOW
static void blk_throtl_update_limit_valid(struct throtl_data *td)
{
struct cgroup_subsys_state *pos_css;
@@ -607,6 +608,11 @@ static void blk_throtl_update_limit_valid(struct throtl_data *td)
td->limit_valid[LIMIT_LOW] = low_valid;
}
+#else
+static inline void blk_throtl_update_limit_valid(struct throtl_data *td)
+{
+}
+#endif
static void throtl_upgrade_state(struct throtl_data *td);
static void throtl_pd_offline(struct blkg_policy_data *pd)
--
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