Re: issues with hwpmc and athlon XP

From: Adrian Chadd <adrian_at_freebsd.org>
Date: Mon, 17 Mar 2008 13:23:20 +0900
On 17/03/2008, Joseph Koshy <jkoshy_at_freebsd.org> 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
process.





Adrian

-- 
Adrian Chadd - adrian_at_freebsd.org
Received on Mon Mar 17 2008 - 03:23:22 UTC

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