* Christoph Lameter ([EMAIL PROTECTED]) wrote: > On Tue, 21 Aug 2007, Mathieu Desnoyers wrote: > > > Using cmpxchg_local vs cmpxchg has a clear impact on the fast paths, as > > shown below: it saves about 60 to 70 cycles for kmalloc and 200 cycles > > for the kmalloc/kfree pair (test 2). > > Hmmmm.. I wonder if the AMD processors simply do the same in either > version.
No supposed to. I remember having posted numbers that show a difference. Are you running a UP or SMP kernel ? If you run a UP kernel, the cmpxchg_local and cmpxchg are identical. Oh, and if you run your tests at boot time, the alternatives code may have removed the lock prefix, therefore making cmpxchg and cmpxchg_local exactly the same. Mathieu -- Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
