A benchmark for a variety of spin-lock implementation using x86 primitives. These variations are as follows: * lock_none.h To provide baseline perfor mance compared to other implementation. * lock_tas.h Naive spin-lock implementaiont with test-and-set('xchg'). * lock_tas_nopause.h Based on lock_tas.h, 'pause' is removed. * lock_tas_mov.h Based on lock_tas.h, lock_release() is improved with 'mov' t