[PATCH] kernel/futex: Change pi_state_update_owner() to an inline function

[Xiangyang Yu]

In our performance tests, we find that the performance of
sysbench is descend. Function call consumes too many instructions,
change pi_state_update_owner() to an inline function.

Test environment:
CPU: Intel(R) Xeon(R) Gold 6154 CPU @ 3.00GHz * 2
MEM: 312G

Test case: https://github.com/akopytov/sysbench
Test cmd: ./sysbench --test=threads --num-threads=$thr
              --thread-yields=100 --thread-locks=2 run

$thr    stock   non-inline   inline
256    0.8511     0.9254     0.8588
512    0.8489     0.9232     0.8503
1024   0.8347     0.9248     0.8495
2048   0.8338     0.9575     0.8402

Signed-off-by: Xiangyang Yu <yuxiangyang4@xxxxxxxxxx>
---
 kernel/futex.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/futex.c b/kernel/futex.c
index e68db7745039..570dee4e9e6f 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -763,7 +763,7 @@ static struct futex_pi_state *alloc_pi_state(void)
 	return pi_state;
 }
 
-static void pi_state_update_owner(struct futex_pi_state *pi_state,
+static inline void pi_state_update_owner(struct futex_pi_state *pi_state,
 				  struct task_struct *new_owner)
 {
 	struct task_struct *old_owner = pi_state->owner;
-- 
2.23.0