Re: [patch v6 10/21] sched: get rq potential maximum utilization

[Alex Shi <alex.shi@intel.com>]

On 04/02/2013 10:38 PM, Vincent Guittot wrote:
>> +static unsigned int max_rq_util(int cpu)
>> > +{
>> > +       struct rq *rq = cpu_rq(cpu);
>> > +       unsigned int rt_util = scale_rt_util(cpu);
>> > +       unsigned int cfs_util;
>> > +       unsigned int nr_running;
>> > +
>> > +       cfs_util = (FULL_UTIL - rt_util) > rq->util ? rq->util
>> > +                       : (FULL_UTIL - rt_util);
> rt_util and rq->util don't use the same computation algorithm so the
> results are hardly comparable or addable. In addition, some RT tasks
> can have impacted the rq->util, so they will be accounted in both
> side.

Thanks Vincent!

Yes, rt_util calculated with different way, but it has very similar
meaning with rq->util. So compare them make sense.

Yes, the rq->util and rt_util have some overlap, so we need to remove
the overlap part, otherwise the total utlization of this cpu will beyond
100%. that's not make sense. And since RT task always has higher
priority than cfs task, here I keep the RT utilization and yield the cfs
utilization.
> 
> Vincent
> 


-- 
Thanks Alex