Messages in this thread | | | Date | Fri, 1 Apr 2016 10:16:39 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH] x86: Calculate MHz using APERF/MPERF for cpuinfo and scaling_cur_freq |
| |
On Fri, Apr 01, 2016 at 12:37:00AM -0400, Len Brown wrote: > From: Len Brown <len.brown@intel.com> > > For x86 processors with APERF/MPERF and TSC, > return meaningful and consistent MHz in > /proc/cpuinfo and > /sys/devices/system/cpu/cpu*/cpufreq/scaling_cur_freq > > MHz is computed like so: > > MHz = base_MHz * delta_APERF / delta_MPERF > > MHz is the average frequency of the busy processor > over a measurement interval. The interval is > defined to be the time between successive reads > of the frequency on that processor, whether from > /proc/cpuinfo or from sysfs cpufreq/scaling_cur_freq. > As with previous methods of calculating MHz, > idle time is excluded.
Is this really a semantic you want to pin down?
Since we're looking at doing something like:
lkml.kernel.org/r/20160303162829.GB6375@twins.programming.kicks-ass.net
We could also just return cpu_khz * whatever fraction we store there, knowing it is something recent.
| |