Author: Aaron Gordon
Date: 18:37:01 08/13/04
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On August 13, 2004 at 14:09:35, Anthony Cozzie wrote: >On August 13, 2004 at 12:44:21, Aaron Gordon wrote: > >>On August 13, 2004 at 11:55:12, Anthony Cozzie wrote: >> >>>On August 13, 2004 at 02:12:04, Aaron Gordon wrote: >>> >>>>All the bad press finally got him redo the review. I told'em a few cflags he >>>>could use to make performance better.. unfortunately he didn't do the PGO >>>>optimization. I think he thought because I said I used GCC 3.4.1 that it was >>>>only available in 3.4.1, who knows.. >>>> >>>>Anyway, looks like the 64bit stuff on the Nacona offers no performance benefit >>>>(only addressing). Would fit with the rumors I heard a few months back. We'll >>>>see I guess. Supposedly they just "got it working" for now and will fix the >>>>performance issue later. >>>> >>>>Anyone know any hard facts about the 64bit Xeon stuff? Broken? >>> >>>I thought Nocona was an implementation of of AMD64 ? >>> >>>anthony >> >>From what I hear it is, however supposedly it only has the addressing of a 64bit >>chip (ie. can use that much ram, can use 64bit integers/fp/etc), but cannot do >>them as fast as it is suppose to be. The way I heard it described was like it >>was using the 32bit registers to do all of the stuff.. similar to a regular P4 >>trying to do a __int64, long long, or double. >> >>I can't verify this, but from the results that Anandtech did it sure looks like >>the rumor may be true. The other part of the rumor was that Intel was going to >>fix it soon. I think this was a quick add-on after they saw x86-64 was the next >>big thing and didn't have time to rework the core to get it functioning 100%. >> >>I guess we'll see in the months ahead... > >Hmm, that would definitely be possible. And _something_ is wrong with the >Crafty benchmark because in 32 bit mode the opteron is not _that_ much faster >than the P4 for Crafty. > >anthony The test was compiled in 64bit mode, which is why the Opteron is getting over 2 million nodes/second. The reason I say the Xeons 64bit stuff could be broken is it was compiled the same way and gains nothing apparently.
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