Request for reviews (S): 7071709: JSR 292: switchpoint invalidation should be pushed not pulled

John Rose john.r.rose at
Thu Aug 25 16:47:13 PDT 2011

On Aug 25, 2011, at 11:32 AM, Tom Rodriguez wrote:

> The docs for VolatileCallSite suggest setTarget can be called whenever you feel like it, so it seems like it can be set many times.  MutableCallSite can be as well but the implication is that it's not updated very often.  I'm actually unclear what distinction is trying to be made with VolatileCallSite.

The MCS and VCS have the same semantics, except for the extra memory barriers on VCS.  These barriers do not affect the validity or applicability of push notification.  Also, either an MCS or VCS might end up being "megamutable", so there has to be some sort of cutoff that will prevent target-prediction for a CS which has been mispredicted too many times.  We need to squeeze a bit of state into the CS, somewhere, which displays how many times the thing has been mispredicted.

-- Joh
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