Sim speed - iMac Pro vs Mac Pro

[sherridge101]

Do you think that the thread issue is a bug?
Would be nice to use all 56 Threads instead of 10 for sims.

[georgi.zhekov]

It's not a bug - when it comes to fluid simulations - processor speed is more important than core count.

NUMA and multiprocessor architectures do not perform well with Phoenix. Simulating on one NUMA node or on limited number of threads is often faster than waiting for multiple nodes to synchronize.

I hope things can be improved in the future, but it's a difficult task to handle so let's see how things go.

[sherridge101]

Cool, thanks for the info.

It's weird how the speed changes across cores though.


5 - slow
10 - faster
12 - a lot slower
20 - faster the 12 etc.

And adding GPU was a little slower.

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5 Threads 1min

10 Threads 33sec

12 Threads 1min 1

20 Threads 45sec

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[sherridge101]

Just want to mention that several artists here had decided that Phoenix was not usable as the sim speed was too slow.

It's pretty important to cover that there seems to be a magic 10 thread (or perhaps 1 thread) somewhere in the manual, where a dead slow sim then becomes somewhat usable.
I've only stumbled across this through persistence as I wanted to keep within the Chaos render family/ecosystem.

[sherridge101]

Just want to mention that several artists here had decided that Phoenix was not usable as the sim speed was too slow.

It's pretty important to cover that there seems to be a magic 10 thread (or perhaps 1 thread) somewhere in the manual, where a dead slow sim then becomes somewhat usable.
I've only stumbled across this through persistence as I wanted to keep within the Chaos render family/ecosystem.

It's pretty important as some people will just assume that phoenix is too slow and move on to Houdini etc.

[georgi.zhekov]

Thanks a lot for the feedback. In your case it is 10 threads, but it really depends on the CPU, generally CPUs with many threads do not scale very well with simulations due to the hardware architecture, but we're always trying to improve the speed.