Linux v2.5.53 pause et al

[Margit Schubert-While]

 > [PATCH] reorder 'rep;nop;' in the spinlock macro
 > According to Intel's recommendation, 'rep;nop; should be called before 
testing
 > if the lock variable was modified (i.e. rep nop;cmp;jcc).
 > The current implementation does it the wrong way around: first test, 
then wait, then branch.
 > I've asked Asit Mallik from Intel, and he recommended to change it.
 > It should be at least consistent: Right now, spinlock uses 'cmp;rep 
nop;jcc',
 > rwlock uses 'rep nop;cmp;jcc'

Hmm. Unless I'm reading it wrong, this doesn't agree with the
example 7-1c on page 7-14 of the P4 Optimization manual,  or ?

This is also interesting  - quote
"The inc and dec instructions should always be avoided. Using add and sub
instructions instead of inc and dec instructions avoid data dependence and
improve performance."

Margit