Re: [RFC/RFT] [PATCH 02/10] cpufreq: intel_pstate: Conditional frequency invariant accounting

Peter Zijlstra
2018-05-17T16:17:15Z

On Thu, May 17, 2018 at 08:41:32AM -0700, Srinivas Pandruvada wrote:
> One more point to note. Even if we calculate some utilization based on
> the freq-invariant and arrive at a P-state, we will not be able to
> control any P-state in turbo region (not even as a cap) on several
> Intel processors using PERF_CTL MSRs.

Right, but don't we need to set the PERF_CTL to max P in order to access
the turbo bins? So we still need to compute a P state, but as soon as we
reach max P, we're done.

And its not as if setting anything below max P is a firm setting either
anyway, its hints all the way down.