RE: Cache coherency... and locking

[Linda Walsh]

> To answer Linda's original question, whether it's necessary to use a lock
> is very much dependent on the operation you're performing. It's safe to
> assume there's an arbitrarily long delay before your write appears to
> another processor, but we're also currently assuming that all writes show
> up in the order they were performed.
---
	Arbitrarily long...no upward bound?  A second, minute, hour, day?  Something
doesn't seem right about that.

	You say we are 'assuming' writes show up in the order performed, that
implies it may not be true?  It seems the speculative read cache would only
stay around for some fixed, finite, and small time -- unless the processor
is halted.  I can see getting the wrong value for the variable on 1 read, but
after performing a system call another read shouldn't still fetch a stale value.
Could it?
-l