Eljay Love-Jensen wrote:
Adding volatile to the g_counter tells the compiler not to optimize away access to the variable, as the variable can change "at any time". That may sound like just the thing for multi-threaded access to the same variable -- but it's not sufficient. Even though the compiler is no longer going to optimize away access to the variable, the hardware can still effectively isolate the two threads from one another, such that neither thread is aware that the g_counter variable has changed. Why? Because each thread could run with the variable stored in separate caches.
Huh? I thought SMP hardware is required to be responsible for cache syncing in such an instance...
-- Matthew Thus sang the fat lady...
