On Tue, 05 Oct 2004 20:19:30 GMT, Leythos wrote:

In article ,
says...
Yes, it's called Windoes XP.

Actually W2000 works fine with HT, and it's completely stable.


MS says the W2000 Server will work, kind of:
http://www.microsoft.com/windows2000...rthreading.doc

Windows 2000 Server Family and Hyper-Threading Technology
Windows 2000 Server does not distinguish between physical and logical
processors on systems enabled with Hyper-Threading Technology; Windows
2000 simply fills out the license limit using the first processors
counted by the BIOS. For example, when you launch Windows 2000 Server
(4-CPU limit) on a four-way system enabled with Hyper-Threading
Technology, Windows will use the first logical processor on each of
the four physical processors, as shown in Figure 2; the second logical
processor on each physical processor will be unused, because of the
4-CPU license limit. (This assumes the BIOS was written according to
Intel specifications. Windows uses the processor count and sequence
indicated by the BIOS.)




http://www.theinquirer.net/?article=18428

Windows 2000 and the hyperthreading nightmare


Having worked at Intel (until just recently) on the Pentium 4, I can
tell you exactly why they recommend disabling HT on older MS OSes.

Windows XP is the first OS (from Billy the Hut) that actually
understands HT. Win2K "should" work, seeing the processor as two CPUs,
but not very efficiently. Win 95/98/ME won't as they are single
processor only, same as the Linux kernel compiled for a UP system - it
just can't see beyond processor 0. Even earlier Linux kernels won't
work properly with HT.

Windows NT 4.0 and Windows 2000 were both released before
hyperthreading was implemented on Intel CPUs. They will identify
“multiple processors” with hyperthreading but they don’t properly
support it. In Windows NT/2000 a hyperthreaded P4 will be recognized
as two processors. In Windows XP a hyperthreaded P4 will be recognized
as a single processor containing two logical processors. So say you
have a Dual Xeon hyperthreaded system. This would be four logical
processors.

Windows 2000 Professional is limited to two processors and doesn’t
recognize the difference between a dual processor hyperthreaded system
and a quad processor non-hyperthreaded system. The 2nd logical
processor on each physical processor would never be used.

Windows XP Professional, on the other hand, would recognise the
difference between the two and would use all four logical processors.
So to answer one of your questions, there actually is more to Windows
XP than "just a fancy eye candy version of Windows 2000".





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