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Subject: Re: Intel doesn't garantuee P4 has hyperthreading in the CPU

Author: Terry McCracken

Date: 23:40:09 11/17/02

Go up one level in this thread


On November 18, 2002 at 02:10:50, Anthony Cozzie 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
>
>
>All P4s have hyperthreading.  You don't maintain "multiple build targets" for a
>CPU, or any other ASIC for that matter :)  However, most of them have it
>disabled.
>
>anthony


http://www.intel.com/homepage/land/hyperthreading_more.htm

http://www.intel.com/support/platform/ht/os.htm

http://www.intel.com/labs/htt/emerqa.htm

http://www.intel.com/home/desktop/pentium4/index.htm

http://www.intel.com/homepage/land/hyperthreading.htm?iid=ipp_dlc_procp4p+body_intro_ht&

http://www.intel.com/eBusiness/products/server/processor/xeon/wp020901_sum.htm?iid=Homepage+htland_ebizxeon&


I think there's a lot more going on then Vincent is willing to tell us;-)

Oh and AMD needs to catch up!:o)



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