RE: Uses for memory barriers

[David Schwartz]

> Am I correct?  Or are there some easily-explained situations where mb()
> really should be used for inter-CPU synchronization?

	Consider when one CPU does the following:

while(!spinlock_acquire()) relax();
x=shared_value_protected_by_spinlock;

	We need to make sure we do not *read* the protected values (say due to
prefetching) before other CPUs see our write that locks the spinlock.

	DS


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