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SubjectRe: frlock and barrier discussion

> Attached is a test app - could someone try it? I don't have access to a SMP
> system right now.

Try to put [g_val1, g_seq1] and [g_val2, g_seq2] on two different cache
lines and run it on a SMP system using CPUs with a partitioned cache
architecture. Even if you do an WMB on writer side, you might see a
different order w/out an RMB on the reader side. This because the two
cache lines might be committed to different partitions with different
loads, and the latest ( in time order ) commit might see a fastest path
due a lower traffic. An RMB on the reader side ( that is usually expensive )
wait for all CPUs's memory controllers to flush their stuff before
resuming execution.

- Davide

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