Hi
I want to use Eigen 3 and multithreading. Therefore I have questions:

1) Does Eigen 3 have a multithreaded "matrix-vector" product?

2) If I use openMP in my program, then Eigen 3 is also multithreaded?
Example:
I have 4 threads, which do some calculations with different parameters - does Eigen 3 use 4 threads or more?

3) Is Eigen 3 "threadsafe", can I use Eigen 3 and Open MPI?

blubber wrote:Hi
I want to use Eigen 3 and multithreading. Therefore I have questions:

1) Does Eigen 3 have a multithreaded "matrix-vector" product?

no, currently only matrix-matrix products are multithreaded.

2) If I use openMP in my program, then Eigen 3 is also multithreaded?
Example:
I have 4 threads, which do some calculations with different parameters - does Eigen 3 use 4 threads or more?

Eigen uses OpenMP for the parallelization, so you can use OpenMP API to control the number of threads, or the function:

Eigen::setNbThreads(n);

to overwrite default OpenMP settings for Eigen only.

3) Is Eigen 3 "threadsafe", can I use Eigen 3 and Open MPI?

Eigen's objects and methods are as thread-safe as a std::vector for instance.

gael

Hi ggael,

no, currently only matrix-matrix products are multithreaded.

is there a reason for that or did you just not have enough time, yet?

Cheers,

Manuel

PS: I'm loving Eigen!

time, and I also need to find a way to factorize the multithreading logic which represent a quite large amount of code and that's far to be trivial.