HTT and SMP question

[Kris Kennaway]

On Tue, Apr 20, 2004 at 11:53:22AM +0300, Rumen Telbizov wrote:
> > > Would you please point out some cases when HTT with machdep.hlt_logical_cpus=0
> > > causes worse performance than machdep.hlt_logical_cpus=1?
> > > I am using an HTT Xeon since recently and in my tests it showed that
> > > machdep.hlt_logical_cpus=0 is better!
> > > A simple ubench (spawning 2 processes) gives better results in 0 mode!
> > 
> > My parallel package builds are slower on build machines with HTT.
> > It's not a magic bullet.
> > 
> > Kris
> 
> Hmm ... interesting. My simple/stupid synthetic tests
> showed just the opposite. Anyway. Unfortunatelly I didn't
> try to buildworld/kernel with -j2 (say). Shame on me!
> 
> Would you point to a case where machdep.hlt_logical_cpus=0 does
> show better performance results? httpd ?
> 
> Is it not that exactly _parallel processing_ should be faster with HTT
> than whithout ?

No, because HTT is not an extra CPU.

Kris
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