On Mon, Jan 13, 2020 at 12:18:46PM +0100, Rafael J. Wysocki wrote: > On Monday, January 13, 2020 11:43:14 AM CET Peter Zijlstra wrote: > > Anyone, what will it take to get MPERF/TSC 'working' ? > > The same thing that intel_pstate does. But intel_pstate cheats, it has a FMS listing and possible 'interesting' chips are excluded. For instance, Core2 has APERF/MPERF, but intel_pstate does not support Core2. Simlarly, intel_pstate does (obviously) not support AMD chips, even tho those have APERF/MPERF. Although I suppose Core2 doesn't have VMX and is therefore less interesting, but then we'd need to gate the logic with something like: static_cpu_has(X86_FEATURE_APERFMPERF) && (static_cpu_has(X86_FEATURE_VMX) || static_cpu_has(X86_FEATURE_SVM) > Generally speaking, it shifts the mperf values by a number of positions > depending on the CPU model, but that is 1 except for KNL. > > See get_target_pstate(). I'm going to go out on a limb and guess that's the same KNL hack as TurboStat has. Is that really the only known case?
