[TriLUG] CPU speed and custom kernel

Sean Alexandre sean at alexan.org
Thu Nov 21 12:44:37 EST 2013


I've built my own kernel, but the CPU runs faster (hotter, more fan noise, etc.)

I can't figure out why it's faster. Everything I've checked is the same between
the two kernels. If I boot to the Debian provided kernel the CPU runs at 800
MHz, but if I boot to my custom kernel it runs at 1.8 GHz. (These are baseline
speeds, after boot without running anything else.)

Here's what I've checked so far:

* Kernel versions are the same. The Debian version is 3.2.0-4-amd64 and the
  version I got from kernel.org is 3.2.52.
* The boot command line has the same paremeters for both: 
  linux /vmlinuz-3.2.0-4-amd64 root=/dev/mapper/tuzo-root ro quiet
* Both boot to the same root file system, and use the same configuration files.
* The .config file used to build the custom kernel is the same as the one used
  to build the Debian kernel. (I'm going to pare it down to just what I need
  once I figure out this problem.)
* Both use the ondemand cpufreq governor.

Is there anything else I should check?

My next step would be to try and build the kernel source from the Debian
package instead of from kernel.org. Maybe this is a code difference?



More information about the TriLUG mailing list