Re: [RFC PATCH v3 3/6] sched: pack small tasks

From: Peter Zijlstra
Date: Tue Mar 26 2013 - 08:26:37 EST


On Fri, 2013-03-22 at 13:25 +0100, Vincent Guittot wrote:
> +static bool is_buddy_busy(int cpu)
> +{
> + struct rq *rq = cpu_rq(cpu);
> +
> + /*
> + * A busy buddy is a CPU with a high load or a small load with
> a lot of
> + * running tasks.
> + */
> + return (rq->avg.runnable_avg_sum >
> + (rq->avg.runnable_avg_period / (rq->nr_running
> + 2)));
> +}

Why does the comment talk about load but we don't see it in the
equation. Also, why does nr_running matter at all? I thought we'd
simply bother with utilization, if fully utilized we're done etc..

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