Hi I use Xubuntu 14.04 to run hmaster and try to run simulation but my system is using only one thread. I tried to find any options from preference but I couldn't so if anybody knows how to use all 12 threads to take an advantage of houdini13? Thank you so much in advance.

This is normal operation as some equations have to run serially, not in parallel.

SMP is well known for this.

What type of simulation? Bullet RBD is not multithreaded, but FLIP and Pyro both are.

In the case of the latter two, you might need to take care to make your Source and Collision geometry as optimized as possible because those are a usually not multithreaded as well as the solver itself and you don't want to waste time there if you can avoid it.

@jason_iversen You are a genius. This simulatin is RBD so I just have to wait! Thank you for taking time teaching me.

@ Jason - does checking ‘Use Parallel Constraint Solver’ help with Bullet multi-threading?