Author: Vincent Diepeveen
Date: 07:15:53 11/18/02
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On November 18, 2002 at 01:28:17, Terry McCracken wrote: >On November 17, 2002 at 13:58:43, Vincent Diepeveen wrote: > >>Hello, >> >>If i read the below section of the intel programming guide very well, >>then i interpret that as: >> >> a) only the Xeon MP has hyperthreading and not the normal P4s, >> not even P4s sold as Northwoods. >> >> b) even the Xeon MP you should not assume that it supports hyper >> threading. In fact something that gets sold as Xeon MP you should >> still not assume that it supports hyper threading, but instead >> one must assume that only after specifically questionning the cpu >> whether it can do it. >> >>Intel IA-32 programming manual. Page 247 (of 780): >>" >>7.6.1 Implementation of Hyper-Threading Technology in IA-32 Processors >> >>Intel's Hyper-threading Technology was introduced into the IA-32 architecture >>in the Intel Xeon processor MP and in the later steppings of the Intel Xeon >>processor. Both of these processors implement Hyper-Threading Technology with 2 >>logical processors per physical processor. When reading the following sections >>(and other sections in this book that refer to this technology), assume that all >>references to the implementation of Hyper-Threading Technology in the Intel Xeon >>processor MP also apply to those later steppings of the Intel Xeon processor >>that implement Hyper-Threading Technology. >> >>Intel recommends that software not rely on IA-32 processor names to determine >>whether a processor supports Hyper-Threading Technology; but instead, it should >>use the CPUID instruction as described in Section 7.6.5, "Detecting >>Hyper-Threading Technology". >>" >> >>Vincent > >Careful, Intel sues! Not at all. They now claim only the > 3Ghz P4s will have hyperthreading enabled, but that's an easy claim, because i cannot check it as the fastest P4 i can test now is 2.53Ghz. With some luck soon also 2.8Ghz P4. At the time the > 3 Ghz P4s are there within say a 6 months or so, of course those statements will have been forgotten. The only official statement is that the group of processors which *might* support SMT is the Xeon MPs and only after you ask the cpu a CPUID and when that response is positive *then* it supports it. So they give ZERO garantuee simply yet. Best regards, Vincent
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