PGI User Forum

KarlW · Joined: 12 Jan 2009 Posts: 23

Hi,
I'm trying to run different code simultaneously on 2 GPUs. I'm under the impression that this requires OpenMP but I can't seem to get the code to work.
pgaccelinfo is picking up both devices and i am using the most recent CUDA drivers etc.

The code at the bottom of the post results in the following messages at run time and then freezes:

call gpu code
number of threads: 2
Section 1, thread: 0
test 1
number of threads: 2
Section 2, thread: 1
no devices found, exiting
launch kernel file=gpu_xyzint_1_openmptest.f90 function=gpu_xyzint_1 line=969 grid=1 block=15

!$OMP PARALLEL SHARED(pint,qint,rint)
tid = OMP_GET_THREAD_NUM()
if (tid.eq.0) then
nthreads = OMP_GET_NUM_THREADS()
end if
print *, 'number of threads:',nthreads
!$OMP SECTIONS
!$OMP SECTION
print *, 'Section 1, thread:', OMP_GET_THREAD_NUM()
print *, 'test 1'
call acc_set_device_num(0,acc_device_default)
!$acc region
!$acc do
do i=1,15
pint(i) = 0
qint(i) = 0
rint(i) = 0
end do
!$acc end region
! call gpucode(ngpu,lgpu)
!$OMP SECTION
print *, 'Section 2, thread:', OMP_GET_THREAD_NUM()
!$acc region
call acc_set_device_num(1,acc_device_default)
!$acc do
do i=16,31
pint(i) = 0
qint(i) = 0
rint(i) = 0
end do
!$acc end region
! call gpucode(ngpu,lgpu)
!$OMP END SECTIONS NOWAIT
!$OMP END PARALLEL

As you can see, I have replaced the call to a separate accelerated subroutine with some simple code. Would the call work when used in this way?

Many thanks,

Karl

mkcolg · Posted: Thu Jul 30, 2009 2:02 pm Post subject:

Hi Karl,

Unfortunately, support for using accelerator regions within OpenMP regions is not in 9.0 yet. (see http://www.pgroup.com/userforum/viewtopic.php?t=1490) We are actively working on adding this and, if all goes well, are expecting preliminary support in September's 9.0-4 monthly release.

Though, I not sure where the "no devices found, exiting" error is coming from. I worked up a small test case using your sample but get the error "libcuda.so not found, exiting". You're welcome to send me the code and I can see what's going on.

Thanks,
Mat

KarlW · Joined: 12 Jan 2009 Posts: 23

Hi Mat,

I was initially getting the libcuda.so error but when I installed the latest cuda version it went away. I thought that issue arose from the installation of the second GPU though.

I've emailed the code to you.

Many thanks,

Karl

edit:
Is there any other way to run different !$acc regions simultaneously on different GPUs?
Also, are there examples anywhere on running a normal region on multiple GPUs?

Cheers!

mkcolg · Posted: Fri Jul 31, 2009 1:36 pm Post subject:

Hi Karlw,

TheMatt · Joined: 06 Jul 2009 Posts: 263 Location: Greenbelt, MD