This is the mail archive of the gcc@gcc.gnu.org mailing list for the GCC project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

RE: spec2k comparison of gcc 4.1 and 4.2 on AMD K8


Honza, 

> Well, rather than unstable, they seems to be more memory layout
> sensitive I would say. (the differences are more or less reproducible,
> not completely random, but independent on the binary itself. I can't
> think of much else than memory layout to cause it).  I always wondered
> if things like page coloring have chance to reduce this noise, but I
> never actually got around trying it.

You didn't mention the processors in your systems, but I wonder if they are dual-core.  If so, perhaps it's got to do with the fact that each K8 core has its own L2, whereas C2 chips have a shared L2.  Then, try preceding "runspec" with "taskset 0x02" to avoid the process from hopping between cores and finding cold caches (though the kernel strives to stick a process to a single core, it's not perfect).

HTH

-- 
_______________________________________________________
Evandro Menezes               AMD            Austin, TX




Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]