On Monday, 6 May 2013 at 10:12:53 UTC, deadalnix wrote:
On Monday, 6 May 2013 at 10:06:50 UTC, Mehrdad wrote:
On Monday, 6 May 2013 at 09:35:59 UTC, Dmitry Olshansky wrote:
You have to read a field to know what to do next, and the
other processor may as well write to it.
That never happens, though. _static is only written to inside
a lock, and the check is inside a lock, hence the other
processor can't be writing to it when it's being read...
Maybe I misunderstood what you're saying?
ON x86 you rarely see this kind of thing as the memory model is
strong. You can see some weird thing in rare cases, but as soon
as you leave x86 world, it isn't even worth trying.
Ah yeah, this entire thing was geared toward x86.
On a second thought, maybe it probably doesn't improve anything
compared to the double-checked lock, since the branch prediction
for 'if' is most likely faster than the branch prediction for a
virtual call anyway. It was worth trying I guess...
