[Sidefx-houdini-list] mantra in H9 - multiprocessor

Mark Alexander malexander at sidefx.com
Fri Oct 5 16:29:17 EDT 2007

> 1 thread  9.01u 0.38s  9.02r
> 2 thread 15.15u 0.42s  7.77r
> 3 thread 56.13u 0.56s 19.02r

Is this a P4 machine with hyperthreading enabled? Because you seem to 
get slightly faster results with 2 threads than 1 (7.77r vs. 9.02r), but 
as soon as 3 threads are chosen, the render time shoots through the 
roof. By default, mantra uses all the processors that the OS reports, 
and with hyperthreading on, the number of processors reported is doubled 
(except that computing power most definitely isn't).

It also could be due to resource contention or cache thrashing within 


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