Re: [RFC PATCH v3 00/16] Core scheduling v3

[Tim Chen]

On 7/18/19 3:07 AM, Aaron Lu wrote:
> On Wed, Jun 19, 2019 at 02:33:02PM -0400, Julien Desfossez wrote:

> 
> With the below patch on top of v3 that makes use of util_avg to decide
> which task win, I can do all 8 steps and the final scores of the 2
> workloads are: 1796191 and 2199586. The score number are not close,
> suggesting some unfairness, but I can finish the test now...

Aaron,

Do you still see high variance in terms of workload throughput that
was a problem with the previous version?

>
>  
>  }
> +
> +bool cfs_prio_less(struct task_struct *a, struct task_struct *b)
> +{
> +	struct sched_entity *sea = &a->se;
> +	struct sched_entity *seb = &b->se;
> +	bool samecore = task_cpu(a) == task_cpu(b);


Probably "samecpu" instead of "samecore" will be more accurate.
I think task_cpu(a) and task_cpu(b)
can be different, but still belong to the same cpu core.

> +	struct task_struct *p;
> +	s64 delta;
> +
> +	if (samecore) {
> +		/* vruntime is per cfs_rq */
> +		while (!is_same_group(sea, seb)) {
> +			int sea_depth = sea->depth;
> +			int seb_depth = seb->depth;
> +
> +			if (sea_depth >= seb_depth)

Should this be strictly ">" instead of ">=" ?

> +				sea = parent_entity(sea);
> +			if (sea_depth <= seb_depth)

Should use "<" ?

> +				seb = parent_entity(seb);
> +		}
> +
> +		delta = (s64)(sea->vruntime - seb->vruntime);
> +	}
> +

Thanks.

Tim