[RC5] RC5-72 Pentium 4 optimizations

Slawek sgp at telsatgp.com.pl
Tue Sep 9 01:02:22 EDT 2003


Andreas Beckmann wrote:

>>Currently I cannot donate much processor time
>>to the project, but I'd like to donate at least the core ;)
>>Who should I send it to?
> Open a new bug in bugzilla http://www.distributed.net/bugs/
> and attach the core there.

Ok, done:
http://n0cgi.distributed.net/bugs/show_bug.cgi?id=3398

It's even faster now :)


>> Oh, and by the way - why those cores work so much slower
>> with hyperthreading enabled?
> 
> Because you have two cores running at the same time fighting
> for the same cpu ressources.
> The core is optimized to fully utilize the cpu, there are no
> ressources left that could be used by a second thread.

Well... the ALUs are underused. It may still be possible to get
some speed improvement using Hyper Threading...

Even with my core that's 30% faster than dg-3-pipe I'm still using
only about 80% of teoretical processing power.


> This might be different for OGR because it involves a lot
> more memory accesses, but noone has investigated the
> influence of hyperthreading on OGR so far.

Optimising OGR might be very funny thing as well :)
"Unfortunatelly" I think operations used there are really
well optimised by the processor itself ;)


-- 
Slawek Piotrowski




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