Hyperthreading in P4 Xeon

[Mikhail Kuzminsky]

According to William Park
> From beowulf-admin at beowulf.org Wed Apr  3 11:52:00 2002
> From: William Park <opengeometry at yahoo.ca>
> To: beowulf at beowulf.org
> Subject: Hyperthreading in P4 Xeon (question)
> 
> What is the realistic effect of "hyperthreading" in P4 Xeon?
  I didn't see any data about applications  which are typical 
for clusters. But there is some other results on Intel Web-site.
The success will depend from application strongly. 
For example, if you have an application, which need full
cache size for working set of pages, the perfornmance of like
application will degrade because at simultaneous running of
2 processes the cache will share.
>  I'm not
> versed in the latest CPU trends.  Does it mean that dual-P4Xeon will
> behave like 4-way SMP?
  Yes, every physical CPU is equal to 2 logical CPUs, and you
may use OpenMP etc.

Mikhail Kuzminsky
Zelinsky Institute of Organic Chemistry
Moscow