> Jan Hubicka wrote: > > >I am running SPEC on both AMD and Intel machines quite commonly and I > >must say that there seems to be difference in between those two. For P4 > >and Core I get results within something like 1-2 SPEC point (0.1%) of > >overall > >SPEC score, for Athlon I was never able to get so close, the > >difference tends to be up to one percent that is often more than > >expected speedup I am looking for. > > > >Of course it might be property of the boxes I have, but there is no > >difference in setup of those machines, just it seems to be happening > >this way. Running the tests more times in sequence tends to stabilize > >Athlon results, so what I often do is to simply configure peak runs to > >do something interesting and use same base runs, since peak scores tends > >to be slightly better than base scores even for identical binaries. > >(that makes development easier, but not GCC better :) > > > > > Interesting, Jan. I did not know that AMD machines are so unstable.
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. Honza
