Author: Robert Hyatt
Date: 07:58:35 11/18/02
Go up one level in this thread
On November 18, 2002 at 10:15:53, Vincent Diepeveen wrote: >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 It isn't only the xeon MT. The MTs are certified for 4-way and 8-way, but the other xeons are also doing hyperthreading. The 2.8's in particular. This is from experience, not from guessing, btw...
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