Mathieu Desnoyers wrote:
I tried it with and without the LOCK prefix on my Pentium 4.
Locked cmpxchg8b : 90 cycles
Non locked cmpxchg8b: 30 cycles
sti: 166 cycles
cli: 159 cycles
So, hrm, even if we use the locked version, it is still much faster than
the sti/cli. I am thoughtful about the comment in asm-i386/system.h:
Curious: what does it look like if the memory is not in cache? I
found that cmpxchg is relatively slower than other rmw instructions
in that case.
--
SUSE Labs, Novell Inc.
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