Malloc performance in a multithreaded environment

Question

I\'ve been running some experiments with the openmp framework and found some odd results I\'m not sure I know how to explain.

My goal is to create this huge matrix a

Answer 1

Technically, the STL vector uses the std::allocator which eventually calls new. new in its turn calls the libc's malloc (for your Linux system).

This malloc implementation is quite efficient as a general purpose allocator, is thread-safe, however it is not scalable (the GNU libc's malloc derives from Doug Lea's dlmalloc). There are numerous allocators and papers that improve upon dlmalloc to provide scalable allocation.

I would suggest that you take a look at Hoard from Dr. Emery Berger, tcmalloc from Google and Intel Threading Building Blocks scalable allocator.