When I render in PP2012, my cpu usage is between 80 and 99% until completed. I have preferences set to render using 8 threads.

However, when I calculate simulations in the cloth room, cpu usage never goes above 25%.

How come? Is this normal? Shouldn't the cloth room be using all the threads too? Is there a setting that I just missed somewhere that changes this? Or could it be a bug?

Thanks.

Run your taskmanager while running a cloth sim to follow the loads among the cores.
The cloth sim uses all of them.
For sync reasons the load is balanced between the cores.
A cloth sym has to be banaced, and can not work as a render where every bucket is actually a stand alone item. (not completely but close)
Cloth has to flow and calculations have to be synchornised.
But is works multicore now.

Vilters,

Single threaded programs seem to use all the cores as well. It is the nature of Windows OS that when work is to be done, even single threaded work, it spreads it around among the cores to keep heat down. You cannot tell if something is single or multithreaded just by watching the load jump around across multiple cores. If heat stays low, my clock runs faster.

You have to look at the total work. I have 8 cores (well technically 4 + hyperthreading, but you know what I mean), and the most load a single thread can produce is 1/8 or 12.5 %. With PP2012 cloth sim peaks at 25% and averages 18%, at least it does on my computer with one sheet of cloth. So 18% is clearly proof that cloth sim is now multi-threaded, as 18 is more than 12.5.

However - bzzzt!! Two-threaded is not what we expect, is it?

I understand that cloth sym has inherent waiting for data in it when multiple threads are needed and it will never be able to use 100% of my 8 cores. But I write multi-threaded apps, and while it does make my brain hurt, I get them to use all the cores at close to 100%. It can be done. Can it be done with cloth sim? I don't know and without studying the matter it would not be fair to claim that it should have been done. However, it has not been done here. No offense to SM, of course. It's just a fact.

@BB
The answer I got from SM was that synchronisation between the cores calculations was the main bottleneck.

A render can be cut in pieces and distributed as buckets among cores, but a cloth calculation that has to be one fluent movement calculated among several cores is not so easy.

sorry Enlish is not my native language, but You know what I mean.

Not so easy - I agree. Very difficult - I do not agree.

Remember - they hire me to write software, not shaders.

Quote - With PP2012 cloth sim peaks at 25% and averages 18%, at least it does on my computer with one sheet of cloth. So 18% is clearly proof that cloth sim is now multi-threaded, as 18 is more than 12.5. However - bzzzt!! Two-threaded is not what we expect, is it?

I understand that cloth sym has inherent waiting for data in it when multiple threads are needed and it will never be able to use 100% of my 8 cores. But I write multi-threaded apps, and while it does make my brain hurt, I get them to use all the cores at close to 100%. It can be done. Can it be done with cloth sim? I don't know and without studying the matter it would not be fair to claim that it should have been done. However, it has not been done here. No offense to SM, of course. It's just a fact.

Even though you didn't reply to me directly, you did answer my question. Thank you.

*Quote -*Remember - they hire me to write software, not shaders.

I know, and you did a fine job if I may say so.

Shaders are your hobby, as morphing is mine.  ;-)
Have a nice day.