Re: [RFC PATCH v2 1/6] sched/fair: Create util_fits_capacity()

[Viresh Kumar]

On 06-04-18, 16:36, Dietmar Eggemann wrote:
> The functionality that a given utilization fits into a given capacity
> is factored out into a separate function.
> 
> Currently it is only used in wake_cap() but will be re-used to figure
> out if a cpu or a scheduler group is over-utilized.
> 
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Signed-off-by: Dietmar Eggemann <dietmar.eggemann@xxxxxxx>
> ---
>  kernel/sched/fair.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 0951d1c58d2f..0a76ad2ef022 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -6574,6 +6574,11 @@ static unsigned long cpu_util_wake(int cpu, struct task_struct *p)
>  	return min_t(unsigned long, util, capacity_orig_of(cpu));
>  }
>  
> +static inline int util_fits_capacity(unsigned long util, unsigned long capacity)
> +{
> +	return capacity * 1024 > util * capacity_margin;

This changes the behavior slightly compared to existing code. If that
wasn't intentional, perhaps you should use >= here.

> +}
> +
>  /*
>   * Disable WAKE_AFFINE in the case where task @p doesn't fit in the
>   * capacity of either the waking CPU @cpu or the previous CPU @prev_cpu.
> @@ -6595,7 +6600,7 @@ static int wake_cap(struct task_struct *p, int cpu, int prev_cpu)
>  	/* Bring task utilization in sync with prev_cpu */
>  	sync_entity_load_avg(&p->se);
>  
> -	return min_cap * 1024 < task_util(p) * capacity_margin;
> +	return !util_fits_capacity(task_util(p), min_cap);
>  }
>  
>  /*
> -- 
> 2.11.0

-- 
viresh