Author: Robert Hyatt
Date: 10:25:41 11/18/02
Go up one level in this thread
On November 18, 2002 at 11:01:05, Vincent Diepeveen wrote: >On November 18, 2002 at 10:58:35, Robert Hyatt wrote: > >>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... > >Not a single P4 i tested so far with the 'smt' turned on is doing it Bob, >of course i do not do a CPUID in DIEP to check whether the chip is supporting >it. > >The statement from intel is very clear. *nowhere* they garantuee it works >and at the Xeon MP it might work after you do a CPUID. > >The results posted by Nalimov here are all from dual Xeon MPs. > >Best regards, >Vincent There are three kinds of intel processors. PIV PIV xeon xeon MP the last two definitely have hyper-threading. I have two here (not MPs as I don't have any quads at the faster clock rates yet). I'm talking about the xeon, not the xeon MP. And they definitely have hyper-threading support... And I don't think Eugene's machines were xeon MPs... the MPs are pricier and really intended for 4-way and 8-way machines... The duals I have here are _not_ MP processors.
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