Linux CPU mismatch issue

investmentbnker75 · 10-18-2010, 04:34 PM

I have an issue where the CPU isnt running at full capacity.

I there some way to enable all the CPU, is it a power setting in the BIOS?

Thanks

neonsignal · 10-18-2010, 04:55 PM

The cpuinfo file shows you the CPU model, but the speed (MHz) is just the speed at the time the file was recorded.

If you want to see the current CPU frequency, use acpitool -c, or look at /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq or similar.

A modern CPU does not run full speed all the time. For most tasks, there are other things that slow down the system (such as access to memory or to the hard disk), so the CPU doesn't have to run full speed to keep up. It is a way of saving power. The operating system will change the speed according to the tasks that are being performed; if you run a program that requires lots of calculations, then you will find that the CPU is pushed up to full speed.

investmentbnker75 · 10-18-2010, 10:30 PM

Is there a way to verify that?

neonsignal · 10-18-2010, 11:53 PM

You might be able to force the higher speed by using the /sys/devices/system/cpu/cpu0/cpufreq/ interface.

The following gives a list of the available governor modes:

Code:

cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors

Typically one of these is "performance"; this can be set by:

Code:

sudo echo performance >/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor

And you can then examine scaling_cur_freq.

Another possible cause of throttling is overheating, for example when a fan has failed.

investmentbnker75 · 10-19-2010, 11:31 AM

The fans are running without failures and the temps seem normal, are there any documents on this issue you can refer me to for this happening on *nix OS's?

Many thanks

TobiSGD · 10-19-2010, 11:50 AM

You can disable this feature by issuing:

Code:

sudo echo performance >/sys/devices/system/cpu/cpu0/cpufreq/performance

But why do you want to do this? Your system will consume more power, will produce more heat, and there is no loss in performance if you keep it enabled.