Author: Robert Hyatt
Date: 09:40:19 01/15/03
I had reported on a few xeon things a while back, and finally cleared up a few things. 1. The 2.2-2.8 xeons _are_ pentium IV core. I had reported that when I used ICC (intel's compiler) to compile for the PIV that the resulting code would not run on my xeon. That was a screw-up on my part. I didn't have ICC working on my linux box at the time, and was compiling on another box instead, using a remote X window. I cleverly forgot about this since Unix makes it pretty well transparent, but the box I compiled on was _not_ a PIV, it was a PIII, and naturally the PIV instructions would wreck the executable on that machine. So a bit of stupidity on my part led to a wrong conclusion. The PIV-instructions compile and run just fine _if_ you run them on a PIV. Which includes my xeon box. 2. The SMT stuff in the xeons is _exactly_ the same as the SMT core in the PIV 3.06ghz. This has been confirmed by an intel engineer although it was pretty certain this was true before I asked. To date there has only been _one_ flavor of SMT that has "gone public" so SMT, if it works on a processor, works the same on that processor as it does on _any_ processor. This only includes the newer xeons and the 3.06 PIV and beyond, but they are all that have SMT so that is enough. Vincent claims different results for different cpus. I (and Intel) suspect that either he is not testing carefully, or he is ignoring bus speeds. The 2.2+ xeons and PIV have varying bus speeds. IE my dual 2.8 has a 400mhz bus speed, while the newer versions of those processors, with the newer 7505 chipset run at 533. It would be expected that comparing two different bus speeds would produce different results. Hope that clears up any mysteries and/or disinformation either I (or others) might have produced. Xeons are definitely PIV's. So far, _all_ SMT implementations are one in the same. Chipsets do vary in bus speed. Etc... BTW I think dell has already moved to the dual 2.8/533mhz version, less than a month after I bought mine at 400. :)
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