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Re: Optimization of conditional access to globals: thread-unsafe?
On Mon, Oct 29, 2007 at 12:04:14 +0300, Tomash Brechko wrote:
> Rather, "...before it released the mutex, and we acuired the same
> mutex". But it may be the same thread actually, so "final value" is
> the value that is seen by the thread at the beginning of excusive
> access to the object. It is "final" wrt previous exclusive access to
> this object.
Note that this doesn't require the value to actually _be_ in the
memory, only to be observed as if it is there. That's the power of
POSIX Threads, and that's why memory barriers, not cache flushes, are
behind pthread_mutex_lock() and friends.