compile question

[Wenbin Yu]

My application is paralleled using openmp. According to the faq, I should compile using make USE_OPENMP=1. However, I am also suggested to usemake USE_THREAD=0 to build single thread OpenBLAS. So do I need to use the following make USE_OPENMP=1 USE_THREADS=0 to achieve what I want to do: achieve the best performance for an application paralleled using OpenMP.

[Enrico Bertolazzi]

I have the same problem.

I use openblas in a multithtread applications. If I use the single thread version of openblas is compiled without USE_LOCKING=1 simply do not work. Compiled using USE_THREADS=0 with USE_LOCKING=1 work but it is slow and slow down application if I use more than 1 thread. The only version that work is to compile using USE_OPENMP=1 USE_THREADS=0 but I need to setup

export OMP_NUM_THREADS=1

or run application with

OMP_NUM_THREADS=1 ./application

I have tried to change the number of thread dynamically inside the applications 

but do not work. It seems that the threads are allocated at startup and there is no way 

to change the behavior. I tried to patch the code forcing the read of OMP_NUM_THREADS=1

inside the code but it do not work. Someone have solved this issue in some way?