|Summary:||CPU frequency in /proc/cpuspeed incorrect on Intel Turbo CPUs or if overclocked|
|Severity:||normal||CC:||alan, dr.diesel, lenb|
Description Andy 2012-08-19 12:56:53 UTC
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.
Comment 1 Alan 2012-08-20 14:48:05 UTC
We don't support overclocked processors. CPUinfo reports what the processor reports.
Comment 2 Andy 2012-08-20 15:37:43 UTC
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.
Comment 3 Len Brown 2012-08-23 02:31:10 UTC
/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.)