[Starpu-devel] About concurrent parallel tasks and OpenMP

[Mirko Myllykoski <mirkom@cs.umu.se>]

Hi,

I am slightly confused about the following statement in the StarPU 
handbook: “For instance, most OpenMP implementations (including the main 
ones) do not support concurrent pragma omp parallel statements without 
nesting them in another pragma omp parallel statement, but StarPU does 
not yet support creating its CPU workers by using such pragma.”

My interpretation is that a situation where two pthreads (StarPU worker 
threads) encounter parallel pragmas concurrently, then something goes 
wrong (thread safety? thread binding?). My understanding that the 
“clustering” is a some type of solution to this problem. Is this 
correct? Can I have concurrent OpenMP-based parallel tasks with 
clusters? If so, how does clustering fix the aforementioned problem? My 
initial guess was that clustering creates the worker threads using a 
parallel pragma but that appears not to be the case.

Best Regards,
Mirko Myllykoski