Re: light weight counters: race free through local_t?

Christoph Lameter
2006-06-15T16:06:55Z

Hmm... What about side effects such as pipeline stalls? fetchadd is
semaphore operation. Typically we use acquire semantics for volatiles.
Here the fetchadd has release semantics.

If we would use release semantics then the fetchadd would require all
prior accesses to be complete.

Acquire semantics may be easier. But the best would be a fetchadd without
any serialization that would be like the inc/dec memory on i386, which
does not exist in the IA64 instruction set.