PC GAMESS/Firefly-related discussion club

Learn how to ask questions correctly

Alex Granovsky
gran@classic.chem.msu.su

On Mon Apr 13 '09 8:03pm, Veinardi Suendo wrote
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>Dear Alex and Firefly Users,

>Actually, we are planning to expand our system to this new processor family due to its HTT. However, does this function really reduce the calculation performance?

As I mentioned earlier, this option may reduce the performance
of programs that are not HTT-aware because of limitations of
current OS kernels. One may expect that this problem will be
fixed soon. As to HTT-aware programs like Firefly, this option
typically improve performance.

> I have checked in the performance section but I could not find the
> benchmark that used all 8 cores (4 real cores + 4 logical cores).
> Is it comparable the performance of one Core i7 machine with 2 Core2 machines?

We have just published results of our recent benchmarks of Intel
Core i7 940 based system with HTT and Turbo Boost Technology enabled,
see the "Performance" section.


> Normally, in Core 2 Quad based machine, I use only:

> $P2P p2p=.t. dlb=.t. xdlb=.t. mxbuf=2048 $END
> $SMP Call64=.t. httpar=.t. httalt=.t. $END

Actually,

 $SMP httpar=.t. httalt=.t. $END

are not needed on Core 2 Quad as there is no HTT support in CPU at all.

>How about in Core i7 machine? Should I add more option in $SMP section such the following?

>$SMP Call64=.t. httpar=.t. httalt=.t. httfix=.t. $END

For Core i7, you need:

 $smp call64=.t. httfix=.t. $end

running on four (or less) cores and using single logical processor of each core.

Alternatively, to run on all eight logical cores, one needs:

 $smp call64=.t. httfix=.f. httpar=.t. smppar=.t. $end

Hope this helps,
Alex