Re: [patch v5 09/15] sched: add power aware scheduling in fork/exec/wake

Alex Shi
2013-02-20T12:09:28Z

On 02/20/2013 05:42 PM, Peter Zijlstra wrote:
> On Mon, 2013-02-18 at 13:07 +0800, Alex Shi wrote:
>> +/*
>> + * Try to collect the task running number and capacity of the group.
>> + */
>> +static void get_sg_power_stats(struct sched_group *group,
>> + struct sched_domain *sd, struct sg_lb_stats *sgs)
>> +{
>> + int i;
>> +
>> + for_each_cpu(i, sched_group_cpus(group)) {
>> + struct rq *rq = cpu_rq(i);
>> +
>> + sgs->group_utils += rq->nr_running;
>> + }
>> +
>> + sgs->group_capacity = DIV_ROUND_CLOSEST(group->sgp->power,
>> + SCHED_POWER_SCALE);
>> + if (!sgs->group_capacity)
>> + sgs->group_capacity = fix_small_capacity(sd, group);
>> + sgs->group_weight = group->group_weight;
>> +}
>
> So you're trying to compute the group utilization, but what does that
> have to do with nr_running? In an earlier patch you introduced the
> per-cpu utilization, so why not avg that to compute the group
> utilization?

I had tried to use rq utilisation in this balancing, but since the
utilisation need much time to accumulate itself(345ms). It's bad for
any burst balancing. So I use instant utilisation -- nr_running.

>

--
Thanks
Alex