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Subject[PATCH] sched/core: add unlikely in group_has_capacity()
Date
1. The group_has_capacity() function is only called in
group_classify().
2. Before calling the group_has_capacity() function,
group_is_overloaded() will first judge the following
formula, if it holds, the group_classify() will directly
return the group_overloaded.

(sgs->group_capacity * imbalance_pct) <
(sgs->group_runnable * 100)

Therefore, when the group_has_capacity() is called, the
probability that the above formalu holds is very small. Hint
compilers about that.

Signed-off-by: Qi Zheng <arch0.zheng@gmail.com>
---
kernel/sched/fair.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 2ba8f230feb9..9074fd5e23b2 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -8234,8 +8234,8 @@ group_has_capacity(unsigned int imbalance_pct, struct sg_lb_stats *sgs)
if (sgs->sum_nr_running < sgs->group_weight)
return true;

- if ((sgs->group_capacity * imbalance_pct) <
- (sgs->group_runnable * 100))
+ if (unlikely((sgs->group_capacity * imbalance_pct) <
+ (sgs->group_runnable * 100)))
return false;

if ((sgs->group_capacity * 100) >
--
2.25.1
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