Re: [RFC 0/3] Experimental patchset for CPPC
Len Brown <[email protected]> Fri, 15 Aug 2014 18:22:10 -0400
| Newsgroups | org.kernel.vger.cpufreq,org.kernel.vger.linux-acpi,org.kernel.vger.linux-kernel |
|---|---|
| Message-ID | <CAJvTdK=hYS87BKZ0NcX7U3RJRmUHWGhC6krSTTmN8O2MO9BK=A@mail.gmail.com> |
> I verified that CPU freq requests were taken by reading out the PERF_STATUS register. Don't use the x86 PERF_STATUS register -- it will not tell you what you want to know. If you want to see the actual frequency, you need to watch how many cycles elapse per a known time interval, which is how intel_pstate and the turbostat utility do it. cheers, Len Brown Intel Open Source Technology Center