issues with hwpmc and athlon XP

Adrian Chadd adrian at
Sun Mar 16 21:23:22 PDT 2008

On 17/03/2008, Joseph Koshy <jkoshy at> wrote:

>  It so happens that the Athlon XP machine I purchased had one of those
>  BIOSes that do not enable the local APIC.  So I couldn't get those
>  PMCs to deliver an interrupt and wasn't able to test sampling on this
>  processor.  That was frustrating, especially since Linux 2.4 and later
>  can override the BIOS and use the LAPIC; we can't.

Hm, why can they but we can't?

>  Onto debugging this bug: my first question is: does system sampling
>  (i.e.. pmcstat -S) work OK on this CPU?

It returned results. I don't know how valid the results were. In fact,
I'm still not getting user-space info from pmcstat -P but that
partially may be user error. I'm seeing NMI's which are logged against
a user trapframe but nothing shows up in my profiling output.. it
could be attributing it to the library/libraries instead of the


Adrian Chadd - adrian at

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