View Full Version : Bullet poor CPU usage

03-12-2014, 06:39 PM
I was wondering if anybody knows the cause of the poor CPU usage when running Bullet. As far as I can see it doesn't support hyperthreading, and even worse, it stays between 15 and 17%. FiberFX, on the other hand, uses the CPU fully. That's just the way it is, right, or is there a way to optimize it to use all cores and power?

03-12-2014, 06:50 PM
Unfortunately it is even worse if you have 16, 24 or more cores! Sadly down to low single digit %!

03-12-2014, 06:57 PM
Well, but at least if you have that many cores everything is fast as hell, especially in Lightwave that can't do network rendering for just one frame.

But I don't complain, at least in Lightwave Bullet works, in Modo it doesn't.

03-13-2014, 07:31 AM
The Bullet library for hard-body dynamics is only single-threaded meaning that any application offering Bullet hard-body dynamics will only be single-threaded. Bullet soft-body dynamics *are* multithreaded, so you can use soft bodies stiffened up to act as hard bodies if you are desperate to see your CPU working hard, but I have found that the dynamics solving takes just as long doing it that way as just using hard bodies single-threaded... YMMV of course :)


03-13-2014, 03:12 PM
I see what you mean, because now I'm running a simulation with one soft body and one kinematic and all 12 cores (6 real and 6 HT) are showing as 100% most of the time. Just curious, why would the usage be so poor when using hard body and optimized when using soft body? Can it be improved?

03-13-2014, 03:40 PM
Soft body = more contact points
A need for more power.

Everything in a computer can improve, you know that, but it will take time for someone to make it so.

03-13-2014, 03:48 PM
I believe that the main author of Bullet, Erwin Coumans, said that multi-threading wouldn't help solution speed but possibly even slow it because of the overhead of communicating with the other cores in your processor.


03-13-2014, 04:42 PM
Interesting thing, I'm testing the same project on an older computer that has an AMD 1090T, six cores and no HT, and the dynamics progress bar is not even showing, and Layout has been frozen for like 40 minutes, with the CPU usage at around 32%.