https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87622
Bug ID: 87622
Summary: coarray does not run in parallel
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: klein at cage dot ugent.be
Target Milestone: ---
I have a minimal co array program
program mini
implicit none
real, dimension(2500,2500),codimension[*] :: a,b
real, dimension(2500,2500) :: c
print *, "start"
!switch b and c and itworks as expected
a=matmul(b,c) !Wast time
print *, "end"
end program mini
There is no interaction between the images. Thus I expect a that running two
images on two cores is as fast as running 1 image on 1 core.
But there runtime doubles it seems that each image does the work of both
images.
Curiossly everything works as expected if I replacte matmul(b,c) by
matmul(c,b). The program runs twice as fast in this case.
