Re: [2.6.28-rc6] oprofile: "opcontrol --start" output two warnings

From: Andi Kleen
Date: Tue Nov 25 2008 - 05:59:36 EST


> if so, I think get_stagger() is a bit strange.
> it depend on caller cpu. then if PREEMPT=Y, it return radom result.

Even without PREEMPT it is random because there is no guarantee the
init code is executing on CPU 0

>
> I'm not sure about oprofile design.
> but if you are right, I think p4_fill_in_addresses shoudn't use smp_processor_id().

Correct.

>
> Am I missing any point?

No you're right. Always returning 0 in get_stagger() should be ok
I think, at least it wouldn't make anything worse.

Or perhaps figure out if the per cpu addresses are really needed,
if yes then this would need much more changes. But I hope
that would not be needed.

But someone should better test it, the P4 perfmon handling is certainly
hairy and I don't claim to understand all its intricate details.

-Andi

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