whitehole_spin: always 0?

[Patrick Palka]

Looks like whitehole_spin is _not_ always 0. Contention just seems to be
really rare.


On Thu, Jul 25, 2013 at 1:32 PM, Patrick Palka <patrick at parcs.ath.cx> wrote:

> It seems that the value of the whitehole_spin counter (as viewable by +RTS
> -s) is always zero, which oddly suggests that there is never any contention
> on the particular atomic operation whitehole_spin is tracking (located in
> copyPart in Evac.c). This may be a symptom of a bug, or it may be the case
> that the atomic operation is not necessary. (Or perhaps contention is just
> very rare. But if contention is rare, why is this operation being counted
> in particular?) Either way, I think this is a bit strange and probably
> worth investigating.
>
> Patrick
>
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