[Bug 41373] Re: High basal cpu load on 686 but not 386 kernel

[Harm van Bakel]

Just tested this by using the 'ati' driver instead of 'fglrx' and
rebooting with the 686 kernel, but this doesn't make any difference. Cpu
usage with the 686 kernel remains high. Even if I shut down X
completely, the high cpu usage still remains. A post by
'no1wantdthisname' (extract pasted below) suggests that this problem is
somehow related to the fact that SMP processing is enabled in the 686
kernel by default. Turning of SMP in a custom compiled kernel solved the
high cpu load problem in his case. Haven't tried yet if this also works
in my case...

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"Just a note: Check your CPU load on the 686 kernel. If it's unusually
high when you're not doing anything, then you should switch back to 386.

I have a sony vaio laptop with a pentium-m processor. Using the 686
kernel causes my cpu to stay steady at ~50%. Using the 386 kernel: my
cpu stays steady at ~1%.

I went ahead and tried building my own kernel. I changed the processor to pentium-m, thinking that the 686 kernel was slow because it was compiling for pentium4. So I went ahead and changed it to pentium m. Even then, the cpu load was still around 50%.
After multiple tries of compiling my own kernel, I noticed that I forgot to turn off SMP. Just by turning off SMP, the load went down to 1%.

Back on breezy, I used the 686 kernel without any problems. However, the
dapper 686 kernel includes SMP by default since it theoretically
shouldn't be causing any problems even on single processor computers. It
seems to be causing the really high cpu load on my laptop though. "

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High basal cpu load on 686 but not 386 kernel
https://launchpad.net/bugs/41373