Re: CPU not running full speed

On Wed, 24 Oct 2007 07:58:29 -0700, Robert Ma wrote:

I have a Dell Precision 360 advertised as P4 2.8 Ghz. On Windows XP and
Debian Linux it is running at 1.6 Ghz. There isn't any setting in the
BIOS to change. I'm wondering what seems to be the problem. Here is the
cpuinfo.

processor : 0
vendor_id : GenuineIntel
cpu family : 15
model : 2
model name : Genuine Intel(R) CPU 2.80GHz stepping : 9
cpu MHz : 1596.126
cache size : 512 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 2
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge
mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe up
cid xtpr bogomips : 3195.37

Thanks.

Modern processors have variable speed clocks which reduce power
consumption, I don't know if your P4 has that feature but I expect that
it does.

Gnome has a widget called the CPU Frequency Scaling Monitor which will
allow you to see what your current clock speed is and to change it if you
want. The default speed governor is On Demand which changes the speed
dynamically depending on the load. There is also a User Mode which allows
you to explicitly set the speed. You can also control the clock speed
from the command line. To see which speed governors you have installed do,

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

The available frequencies are

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

The current governor is

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

The current clock is
cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq

You can change the governor by writing into the scaling_governor and
scaling_cur_freq files. For example

echo userspace > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
echo # > /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed

Where # is the speed you want. The Gnome widget is more convenient but
the CLI approach works too. I suspect that KDE has a similar widget, I
don't know what it's called.


Windows has no equivalent tool, it has various power management options
but none of those allow you to directly control the clock speed.
.