When CPU is in standard Turbo mode /proc/cpuinfo and turbostat -v do not display the same value. If CPU is overclocked /proc/cpuinfo is not correct on any speedstep, idle or at max. turbostat is correct when overclocked. A bit of info here: https://bugzilla.redhat.com/show_bug.cgi?id=746372 I don't understand the underlying principles but /proc/cpuinfo should be fixed by using the methods used in turbostat or some other method like the one listed at the bottom of this link: http://code.google.com/p/i7z/ My testing was done on a Fedora 17 64bit box with mainline kernels, Asus MB and an Intel(R) Core(TM) i5-2500K CPU @ 3.30GHz overclocked to 4.4Ghz. Happy and willing to test any and all patches.
We don't support overclocked processors. CPUinfo reports what the processor reports.
It doesn't display the correct frequency when in Turbo mode either, which is a normal supported Intel feature. Intel K processors are factory unlocked and meant to be run at the desired frequency, slower or faster. Underclocked, for embedded high temperature applications should be supported as well. Adapting /proc/cpuinfo to "read" like turbostat or i7z would fix all the individual situations.
/proc/cpuinfo is simply not intended to report the average running frequency. It is not a bug that it doesn't -- it is a feature request. (which would be a bad idea to do in the kernel, btw.)