Re: [PATCH 8/8] sched: prefer cpufreq_scale_freq_capacity

[Peter Zijlstra]

On Wed, Mar 16, 2016 at 07:44:33PM +0000, Dietmar Eggemann wrote:
> intel_pstate (setpolicy()) is an exception but my humble guess is that
> systems with intel_pstate driver have X86_FEATURE_APERFMPERF support.

A quick browse of the Intel SDM says you're right. It looks like
everything after Pentium-M; so Core-Solo/Core-Duo and onwards have
APERF/MPERF.

And it looks like P6 class systems didn't have DVFS support at all,
which basically leaves P4 and Pentium-M as the only chips to have DVFS
support lacking APERF/MPERF.

And while I haven't got any P4 based space heaters left, I might still
have a Pentium-M class laptop somewhere (if it still boots).