The patch adds cpu_relax() in the body of some spin loops for 2.6.9.  The
patch also removes redundant barrier() code after cpu_relax() on ia32.

In the PAUSE instruction section, IA32 SDM claims "it is recommended that a
PASUE instruction be placed in all spin-wait loops".  And x86_64 SDM says
that PAUSE instruction is same as legacy mode in IA-32e mode operation.

This patch is against 2.6.9 (kernel.org).  It was tested on ia32 and
x86_64.
Acked-by: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>