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Old May 19th 04, 06:53 PM
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Default Fritz8 programs and Intel Hyper-Threading

SethB wrote:

But you can turn it off in bios ... engine works 100%

I could try that sometime to see if it makes 2x difference in the std
version, after I buy it. I'm no longer considering the dual processor
version of Fritz8. Guess that's what I was trying to decide. Thanks
very much.

Here is another data point for comparison. I have tried running Crafty
on my P4 machine, with and without hyperthreading enabled. I configured
Crafty at first to use "only 1 CPU". These are the results:

With hyperthreading enabled:

- Windows Task Manager reports 50% cpu usage.
- the "bench" command in Crafty gives 1202437 nodes/second.

With hyperthreading disabled:

- Windows Task Manager reports 100% cpu usage.
- the "bench" command in Crafty gives 1220120 nodes/second.

So, when HT is enabled, although the task manager reports 50% (i.e. one
of the "two" virtual CPUs is fully occupied), the cpu is apparently
delivering about 98% of its potential (when running this piece of
software, configured this way). If you configure Crafty to use 2 CPUs,
and enable hyperthreading, then there is a slight improvement:

With hyperthreading enabled and Crafty configured to use two threads:

- Windows Task Manager reports 100% cpu usage.
- the "bench" command in Crafty gives 1317634 nodes/second.

If these findings were repeated with Fritz8, then you would expect that
HT makes no difference to the single processor version of Fritz; and
that the multi-processor version of Fritz might see roughly a 10% speed
increase when HT is turned on.