Re: [RFC] sched: fair: Don't update CPU frequency too frequently

[Peter Zijlstra]

On Thu, Jun 01, 2017 at 05:04:27PM +0530, Viresh Kumar wrote:
> This patch relocates the call to utilization hook from
> update_cfs_rq_load_avg() to task_tick_fair().

That's not right. Consider hardware where 'setting' the DVFS is a
'cheap' MSR write, doing that once every 10ms (HZ=100) is absurd.

We spoke about this problem in Pisa, the proposed solution was having
each driver provide a cost metric and the generic code doing a max
filter over the window constructed from that cost metric.