[PATCH] sched/fair: fix contribution calculation

From: Ganesh Mahendran
Date: Wed Jul 05 2017 - 04:46:49 EST


Function __compute_runnable_contrib() is to calculate:
\Sum 1024*y^n {for (1..n_period)}
But LOAD_AVG_MAX returns sum of 1024*y^n (0..n_period).
So we need to subtract 1024*y^0.

Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Ganesh Mahendran <opensource.ganesh@xxxxxxxxx>
---
kernel/sched/fair.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 90e26b1..777ad49 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2508,7 +2508,7 @@ static u32 __compute_runnable_contrib(u64 n)
if (likely(n <= LOAD_AVG_PERIOD))
return runnable_avg_yN_sum[n];
else if (unlikely(n >= LOAD_AVG_MAX_N))
- return LOAD_AVG_MAX;
+ return LOAD_AVG_MAX - 1024;

/* Compute \Sum k^n combining precomputed values for k^i, \Sum k^j */
do {
--
1.9.1