[PATCH V2] sched: Introduce util_est boost

[王擎]

This patch is the simple implementation part of
"Improving responsiveness of interactive CFS tasks using util_est" by
Vincent. 

I would like to ask for your comments.

Thanks,
Qing


>From: Wang Qing <wangqing@xxxxxxxx>
>
>Util_avg is greater than util_est means there is a sudden increase in
>tasks at this time, we should give it an increment to make load balancing
>faster.
>
>Signed-off-by: Wang Qing <wangqing@xxxxxxxx>
>---
>v2:
>- modify the return value if UTIL_EST_BOOST is false
>---
> kernel/sched/fair.c     | 8 +++++++-
> kernel/sched/features.h | 1 +
> 2 files changed, 8 insertions(+), 1 deletion(-)
>
>diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
>index 265bf7a75a37..2fcda7972057 100644
>--- a/kernel/sched/fair.c
>+++ b/kernel/sched/fair.c
>@@ -4036,7 +4036,13 @@ static inline unsigned long _task_util_est(struct task_struct *p)
> 
> static inline unsigned long task_util_est(struct task_struct *p)
> {
>-       return max(task_util(p), _task_util_est(p));
>+       unsigned long util_avg = task_util(p);
>+       unsigned long util_est = _task_util_est(p);
>+
>+       if (sched_feat(UTIL_EST_BOOST) && util_est && util_avg > util_est)
>+               return util_avg + (util_avg - util_est)/2;
>+       else
>+               return max(util_avg, util_est);
> }
> 
> #ifdef CONFIG_UCLAMP_TASK
>diff --git a/kernel/sched/features.h b/kernel/sched/features.h
>index 1cf435bbcd9c..c73a898e7e38 100644
>--- a/kernel/sched/features.h
>+++ b/kernel/sched/features.h
>@@ -95,6 +95,7 @@ SCHED_FEAT(WA_BIAS, true)
>  */
> SCHED_FEAT(UTIL_EST, true)
> SCHED_FEAT(UTIL_EST_FASTUP, true)
>+SCHED_FEAT(UTIL_EST_BOOST, false)
> 
> SCHED_FEAT(LATENCY_WARN, false)
> 
>-- 
>2.7.4