[ltp] Frustrating powertop results for a22m

Connor Behan linux-thinkpad@linux-thinkpad.org
Thu, 14 Feb 2008 15:09:08 -0500


If I run Powertop when X is running, about 50% of my wakeups say "extra 
timer interrupt" and if X is not running, about 80% of them say that. 
All of the suggestions online of how to fix this say to enable CPU 
frequency scaling and to set HPET as the timer.

My a22m has a 900Mhz Mobile Pentium III with Speedstep according to 
Thinkwiki. However, I tried to load cpufreq modules and the only one 
that will load is speedstep-lib and I need one like speedstep-smi or 
speedstep-ich to actually enable frequency scaling. The cpufreq 
documentation says SOME PIII Coppermine processors will work but not 
all. Is this one of the ones that has the primitive Speeedstep, in that 
you can choose normal operating mode or power saving mode in the BIOS 
and that's it? Because I tried the one that's optimized for battery life 
and it does little to help. My battery life is about 4 hours but there 
are still plenty of extra timer interrupts. If this is one of the 
Coppermines that can use cpufreq, there must be some trick to setting it 
up, because I can't figure it out.

Also, I don't think the system board has an HPET timer. I tried setting 
the clock=hpet kernel parameter but there were just as many extra timer 
interrupts as before, so I think it ignored the parameter and used 
clock=pit again.

I'm willing to accept that my laptop is just too old to be efficient, 
but if there is some way to make it more efficient that I haven't 
thought of, could you tell me?  Thanks.