Tom wrote:
> > [ compare_and_swap man page ]
>
> Looks kinda baroque. What about the referenced fetch_and_or routine?
> If that's atomic it might be closer to TAS semantics.
Thanks for the hint!
Tatsuo, can you try the performance of fetch_and_or on your machine ?
Replace the cs() line in s_lock.h with the following:
<-- #define TAS(lock) cs((int *) (lock), 0, 1)
--> #define TAS(lock) fetch_and_or(lock, 1)
On my machine the various implemtations have the following runtimes:
(with a modified s_lock test that does not sleep, and SPINS_PER_DELAY 100000)
with LinuxPPC asm: 1m5.16s (Which may not work relyably on SMP)
with cs: 1m12.25s
with fetch_and_or: 1m26.71s
I don't know if that is enough difference to worry about.
Andreas