Hyperthreading in P4 Xeon (question)

William Park opengeometry at yahoo.ca
Wed Apr 3 15:32:27 EST 2002


On Wed, Apr 03, 2002 at 10:50:06AM -0500, Mark Hahn wrote:
> > What is the realistic effect of "hyperthreading" in P4 Xeon?  I'm not
> > versed in the latest CPU trends.  Does it mean that dual-P4Xeon will
> > behave like 4-way SMP?
> 
> for some value of "behave like" ;)
> that is, it will definitely NOT get twice as fast.  but it will appear
> to have 4 CPUs, and can run 4 threads/procs at once (for values of 
> "once" > 1 clock cycle ;)
> 
> we did a quick test on a dual-prestonia here, and saw a ~5% speedup
> on a probably cache-friendly, compute-bound task.

Hi Mark, Steve, and Michael,

Can you try compiling your kernel, using
    make clean; time make     bzImage modules >& j1
    make clean; time make -j2 bzImage modules >& j2
    make clean; time make -j4 bzImage modules >& j4

-- 
William Park, Open Geometry Consulting, <opengeometry at yahoo.ca>
8 CPU cluster, NAS, (Slackware) Linux, Python, LaTeX, Vim, Mutt, Tin
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