Thread: mwait/monitor example

The answer to this stackoverflow question is quite extensive. I suggest you read it, it contains everything you'd want to know.

Code:

struct MonitoredType
{
  int (*event)(struct MonitoredType const* m);              /*Return 0 to keep monitoring*/
  struct AnyType data;                                /*Less, in size, than MIN_MONITOR_RANGE*/
  char padding[MAX_MONITOR_RANGE - sizeof(AnyType)];
};

void wait_for_write(struct MonitoredType const* m)
{
   /* This may miss a write if it happens before MONITOR, beware of race conditions if necessary */
   do
   {
     _mm_monitor(&m->data, 0, 0);
     _mm_mwait(0, 0);
   } while ( ! m->event(m));
}

Any use of concurrency and parallelism can lead to buggy code if you don't use it the way it was meant to be used.