[Bug libfortran/51119] MATMUL slow for large matrices

[jvdelisle at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=51119

--- Comment #24 from Jerry DeLisle <jvdelisle at gcc dot gnu.org> ---
(In reply to Jerry DeLisle from comment #16)
> For what its worth:
> 
> $ gfc pr51119.f90 -lblas -fno-external-blas -Ofast -march=native 
> $ ./a.out 
>  Time, MATMUL:    21.2483196       21.254449646000001     1.5055670945599979
> 
>  Time, dgemm:    33.2441711       33.243087289000002      .96260614189671445
> 

Running a sample matrix multiply program on this same platform using the
default OpenCL (Mesa on Fedora 22) the machine is achieving:

64 x 64      2.76 Gflops
1000 x 1000  14.10
2000 x 2000  24.4