CPU speed and cat /proc/cpuinfo

Question

I use centos 6.4 64. I have old proc - CPU AMD Phenom II X4 810 (HDX810W) 2.6 GHz. However, when I execute the command cat /proc/cpuinfo I get the following:

processor   : 0
vendor_id   : AuthenticAMD
cpu family  : 16
model       : 4
model name  : AMD Phenom(tm) II X4 810 Processor
stepping    : 2
cpu MHz     : 800.000
cache size  : 512 KB
physical id : 0
...

All four cores have the same speed 800 MHz. How to explain it?

Answer 1

That's the current CPU frequency; it can be scaled up and down.

Have a look in /sys/devices/system/cpu/cpu0 (or 1, 2, 3), then the cpufreq directory.

Check cat scaling_governor. It is probably ondemand (I believe that's the default kernel configuration). Now check scaling_available_frequencies; you'll see a list that for you should start with 2600000.

The kernel will boost the frequency when required. Try a busy loop, with bash:

while (( 1 )); do echo busy; done

Let that go and check your frequencies. They should go up. If you have a CPU monitor and one of them hits close to 100%, that core will probably be at the max frequency now.