Re: [RFC 4/6] mm, thp: move collapsing from khugepaged to task_work context

[Peter Zijlstra]

On Mon, Feb 23, 2015 at 01:58:40PM +0100, Vlastimil Babka wrote:
> @@ -7713,8 +7820,15 @@ static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued)
>  		entity_tick(cfs_rq, se, queued);
>  	}
>  
> -	if (numabalancing_enabled)
> -		task_tick_numa(rq, curr);
> +	/*
> +	 * For latency considerations, don't schedule the THP work together
> +	 * with NUMA work. NUMA has higher priority, assuming remote accesses
> +	 * have worse penalty than TLB misses.
> +	 */
> +	if (!(numabalancing_enabled && task_tick_numa(rq, curr))
> +						&& khugepaged_enabled())
> +		task_tick_thp(rq, curr);
> +
>  
>  	update_rq_runnable_avg(rq, 1);
>  }

That's a bit yucky; and I think there's no problem moving that
update_rq_runnable_avg() thing up a bit; which would get you:

static void task_tick_fair(..)
{

	...

	update_rq_runnable_avg();

	if (numabalancing_enabled && task_tick_numa(rq, curr))
		return;

	if (khugepaged_enabled() && task_tick_thp(rq, curr))
		return;
}

Clearly the return on that second conditional is a tad pointless, but
OCD :-)
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