The registers aren't shared here, but the main memory is. The example has each thread write '1' into a [shared, main] memory location and then read the other thread's memory location into a register. If both CPUs' registers are 0, that means that both reads occurred before both writes.
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I hope this isn't too dumb, but I always imagined each processor having its own set of registers.
Am I incorrect? I can't see how multiple processors can share registers without chaos?
The registers aren't shared here, but the main memory is. The example has each thread write '1' into a [shared, main] memory location and then read the other thread's memory location into a register. If both CPUs' registers are 0, that means that both reads occurred before both writes.
Of course they have different registers, but they sure don't have different memory.