RE: JavaMemoryModel: Volatiles - where does SC work and PO doesn' t

From: Hudson, Rick (rick.hudson@intel.com)
Date: Tue Nov 21 2000 - 17:59:20 EST


The property we are looking at is what you have illustrated, it is weaker
than what has been proposed for Java.

- Rick
PS.
The use of the term PO was a mistake and should not be construed to refer to
any actual implementation.

-----Original Message-----
From: Jeremy Manson [mailto:jmanson@cs.umd.edu]
Sent: Tuesday, November 21, 2000 10:35 AM
To: javamemorymodel@cs.umd.edu
Subject: RE: JavaMemoryModel: Volatiles - where does SC work and PO
doesn't

> All processors will see writes made by a particular processor in the order
> written, aka processor order.

Let me make sure I understand this. To illustrate the difference,
initially, A = B = 0.

P1
A = 1

P2
u = A
v = B

P3
B = 1

P4
w = B
x = A

The result u = 1, v = 0, w = 1, x = 0 is possible under PO but not SC.
Is that right?

Obviously, this in and of itself isn't terribly useful. Is it difficult
to contrive an example where this pattern is used?

                                        Jeremy
-------------------------------
JavaMemoryModel mailing list - http://www.cs.umd.edu/~pugh/java/memoryModel

-------------------------------
JavaMemoryModel mailing list - http://www.cs.umd.edu/~pugh/java/memoryModel



This archive was generated by hypermail 2b29 : Thu Oct 13 2005 - 07:00:28 EDT