RE: JavaMemoryModel: The range of memory models now in play

From: Sarita Adve (
Date: Thu Aug 08 2002 - 17:26:04 EDT


> -----Original Message-----
> From:
> [] On Behalf Of Bill Pugh
> Sent: Thursday, August 08, 2002 3:11 PM
> To:; Sarita Adve
> Cc:
> Subject: JavaMemoryModel: The range of memory models now in play

> Jason and Sarita: do you agree that your models fit between A and B?

This is correct for my model except for one technicality below, which
may or may not matter depending on the direction you want to take this

> Consider two programming models, A and B.
> In both models, you check the validity of a totally ordered
> execution trace E.

Saying only that an execution trace is totally ordered is somewhat
"content-free" unless some properties are assigned to the total
ordering. I believe for model B, you are implicitly assuming that the
above total order is consistent with program order. For my model, I can
also construct a total order where a read returns the value from a
previous write. But this order isn't consistent with program order, and
for hardware with caches and write buffers, this order would be on write
suboperations rather than write operations, but I don't think you were
considering such orders.

Also, there is more similarity between your and my model, but I assume
you will get to that in a subsequent message.


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