Hi,
About the Intel HT processor for Scientific
calulation , I just want to share my opinion that as
Andras pointed out HT is no good. I had difficult time
with HT program written to do monte carlo analysis.
Regards,
Ganesh
--- Andras Szabo <szaboan_at_[hidden]> wrote:
> Hi Robin
>
> As far as I know, the HyperThreading capable Intel
> processors have no
> additonal floating poitnt execution
> units, so if your application is numerically
> intensive, then (in theory)
> there will be no performance improvements
> even if the scheduler makes good work. When you are
> using a program
> which makes integer calculations (and
> hasn't got memory bottleneck eg. compiling), then
> you should gain some
> benefit from HT.
>
> My personal opinion is that widely used scientific
> codes doesn't really
> work well with HT (it is not designed
> for this purpose).
>
> Probably the best thing you should do, is to give it
> a try and see what
> happens. If you do so then you should use
> 2.6.x Linux kernel series, because of the better HT
> support and
> advanced scheduling techniques.
>
> Regards
>
> Andras Szabo
>
>
>
> Robin Humble wrote:
>
> >On Thu, Jun 24, 2004 at 09:15:13PM -0400, Yaron
> Minsky wrote:
> >
> >
> >>One important thing is if you're not going to put
> 4 processors per
> >>node (which isn't worth it in my experience), then
> turn hyperthreading
> >>off. If you don't, then depending on the
> scheduler you may get two
> >>
> >>
> >
> >definitely.
> >If changing HT settings in BIOS on a whole cluster
> doesn't appeal, then
> >with oldish 2.4 kernels (< 2.4.22?) the 'noht' boot
> option works, and
> >with new 2.6 kernels 'maxcpus=2' is the boot
> option.
> >for kernels in between, compiling with
> CONFIG_NR_CPUS=2 most likely
> >will work (but you should test it).
> >
> >cheers,
> >robin
> >_______________________________________________
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> >
> >
> >
>
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