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View Full Version : iBook whups Dual G4 in Screamernet??



Johnny
06-30-2003, 09:43 PM
I have a 60-frame test render going right now with Screamernet, using a DP 450 and a 600mhz iBook.

while the total count produced by the Dual 450 is greater than that produced by the iBook, the iBook's single G3 Chip has pumped out more frames than either G4 chip has (7 as opposed to 6)

usually, the G4 whips the iBook silly at most things..why not at this? I'm happy to see the iBook running like a champ, but could I do something to make the dual G4's performance better? Each processor in the G4 is a node, has its own LWSN and LWSN cmd Line, as does the iBook.

thanks!

Johnny

(Both Macs running 10.2.4, iBook has 640 MB RAM, the G4 has 1.5 GB)

Beamtracer
06-30-2003, 09:58 PM
The Dual G4 450MHz only has two advantages over the G3 600MHz iBook... dual processing and altivec.

Also, don't forget that a dual processor machine isn't twice as fast as a single processor machine at the same clockspeed. This is because there's a bit of overhead in a multiprocessor environment.

Julian Johnson
07-01-2003, 02:31 AM
Hi Johnny,

How many threads are each of the LWSNs on the G4 using? For optimal speed they should be using 1. Check the Lightwave Layout 3 Prefs files that your G4 LWSNs are using and see if the thread count is set to 1. My guess is both your G4 LWSNs and your G3 LWSN are using a single set of Lightwave Layout 3 Prefs with a thread count greater than 1. Multiple threads will benefit the single processor G3 but won't help the performance with dual processors on the G4.

Just a guess, though.

Julian

joshmaker
07-03-2003, 02:11 PM
Originally posted by Julian Johnson
Multiple threads will benefit the single processor G3 but won't help the performance with dual processors on the G4.
Hmmm... that is odd -- I have a Dual 500MHz G4 and in the (admittedly few and possibly flawed) LightWave benchmarking renders I have done, my picture always seemed to run fastest at the highest thread settings.

Johnny
07-03-2003, 03:33 PM
exactly what IS a 'thread?'

Is it a process? a chain of computational instructions?

J

Julian Johnson
07-04-2003, 03:51 AM
joshmaker - I'm talking specifically about LWSN not Layout. LWSN doesn't seem to behave in the same way as Layout when it comes to multiple threads. If you have two instances of LWSN on a dual CPU machine with the thread count in Lightwave Layout 3 Prefs set to anything higher than 1, the renders will take longer than if the thread count was set to 1.

If you're only running a single instance of LWSN on a dual machine, then increasing the threads helps marginally although not the same way it does with Layout. So the rule is: with two instances of LWSN on a dual machine, always set the thread count to 1. With a single instance of LWSN on a dual machine, increase the thread count.

Layout will perform most of the benchmarks substantially quicker with a thread setting higher than 1.

Julian

joshmaker
07-06-2003, 04:46 PM
Ahhhhhh.
Well, that makes sense. Thanks.