Re: [PATCH]sched: convert wall-time to vruntime forcheck_preempt_tick

[Mike Galbraith]

On Thu, 2011-04-07 at 20:43 +0800, Shaohua Li wrote:
> In check_preempt_tick(), delta is vruntime and ideal_runtime is wall runtime.
> Comparing vruntime and ideal_runtime looks buggy.

Why is that buggy?  It's a distance in units ns, ala wakeup_granularity,
a number.  This number just happens to be variable.

> Signed-off-by: Shaohua Li <shaohua.li@xxxxxxxxx>
> 
> diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
> index 3f7ec9e..0b76e3a 100644
> --- a/kernel/sched_fair.c
> +++ b/kernel/sched_fair.c
> @@ -1121,7 +1121,7 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
>  		if (delta < 0)
>  			return;
>  
> -		if (delta > ideal_runtime)
> +		if (delta > calc_delta_fair(ideal_runtime, curr))
>  			resched_task(rq_of(cfs_rq)->curr);
>  	}
>  }
> --
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