atomic-up.h speedup : compared with irq disable/enable

Some more information about the non LOCKed atomic ops that I now use on SMP :

A test ran on a 3GHz Pentium 4 shows that (20000 loops) :

irq save/restore pair      210.60 ns

cmpxchg                     49.46 ns
    (76 % speedup)
cmpxchg-up (no lock prefix)  9.00 ns
    (95 % speedup)

Does anyone still believe that cli()/sti() is faster ? :)

Mathieu

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