No problem, anyways I think you are headed in the right direction now.
--td
David Akin wrote:
Sorry for the confusion. What I need is for all OpenMP threads to
*not* stay on one core. I *would* rather each OpenMP thread to run on
a separate core. Is it my example code? My gut reaction is no because
I can manipulate (somewhat) the cores the threads are assigned by
adding -bysocket -bind-to-socket to mpirun.
On Thu, Jul 29, 2010 at 10:08 AM, Terry Dontje
<terry.don...@oracle.com <mailto:terry.don...@oracle.com>> wrote:
Ralph Castain wrote:
On Jul 29, 2010, at 5:09 AM, Terry Dontje wrote:
Ralph Castain wrote:
How are you running it when the threads are all on one core?
If you are specifying --bind-to-core, then of course all the threads will
be on one core since we bind the process (not the thread). If you are
specifying -mca mpi_paffinity_alone 1, then the same behavior results.
Generally, if you want to bind threads, the only way to do it is with a
rank file. We -might- figure out a way to provide an interface for thread-level
binding, but I'm not sure about that right now. As things stand, OMPI has no
visibility into the fact that your app spawned threads.
Huh??? That's not completely correct. If you have a multiple
socket machine you could to -bind-to-socket -bysocket and spread
the processes that way. Also couldn't you use the
-cpus-per-proc with -bind-to-core to get a process to bind to a
non-socket amount of cpus?
Yes, you could do bind-to-socket, though that still constrains
the threads to only that one socket. What was asked about here
was the ability to bind-to-core at the thread level, and that is
something OMPI doesn't support.
Sorry I did not get that constraint. So to be clear what is being
asked is to have the ability to bind a processes threads to
specific cores. If so then to the letter of what that means I
agree you cannot do that.
However, what may be the next best thing is to specify binding of
a process to a group of resources. That's essentially what my
suggestion above is doing.
I do agree with Ralph that once you start overloading the socket
with more threads then it can handle problems will ensue.
--td
This is all documented in the mpirun manpage.
That being said, I also am confused, like Ralph, as to why no
options is causing your code bind. Maybe add a
--report-bindings to your mpirun line to see what OMPI thinks it
is doing in this regard?
This is a good suggestion - I'm beginning to believe that the
binding is happening in the user's app and not OMPI.
--td
--td
On Jul 28, 2010, at 5:47 PM, David Akin wrote:
All,
I'm trying to get the OpenMP portion of the code below to run
multicore on a couple of 8 core nodes.
Good news: multiple threads are being spawned on each node in the run.
Bad news: each of the threads only runs on a single core, leaving 7
cores basically idle.
Sorta good news: if I provide a rank file I get the threads running on
different cores within each node (PITA.
Here's the first lines of output.
/usr/mpi/gcc/openmpi-1.4-qlc/bin/mpirun -host c005,c006 -np 2 -rf
rank.file -x OMP_NUM_THREADS=4 hybrid4.gcc
Hello from thread 2 out of 4 from process 1 out of 2 on c006.local
another parallel region: name:c006.local MPI_RANK_ID=1 OMP_THREAD_ID=2
Hello from thread 3 out of 4 from process 1 out of 2 on c006.local
another parallel region: name:c006.local MPI_RANK_ID=1 OMP_THREAD_ID=3
Hello from thread 1 out of 4 from process 1 out of 2 on c006.local
another parallel region: name:c006.local MPI_RANK_ID=1 OMP_THREAD_ID=1
Hello from thread 1 out of 4 from process 0 out of 2 on c005.local
another parallel region: name:c005.local MPI_RANK_ID=0 OMP_THREAD_ID=1
Hello from thread 3 out of 4 from process 0 out of 2 on c005.local
Hello from thread 2 out of 4 from process 0 out of 2 on c005.local
another parallel region: name:c005.local MPI_RANK_ID=0 OMP_THREAD_ID=3
another parallel region: name:c005.local MPI_RANK_ID=0 OMP_THREAD_ID=2
Hello from thread 0 out of 4 from process 0 out of 2 on c005.local
another parallel region: name:c005.local MPI_RANK_ID=0 OMP_THREAD_ID=0
Hello from thread 0 out of 4 from process 1 out of 2 on c006.local
another parallel region: name:c006.local MPI_RANK_ID=1 OMP_THREAD_ID=0
another parallel region: name:c005.local MPI_RANK_ID=0 OMP_THREAD_ID=3
another parallel region: name:c005.local MPI_RANK_ID=0 OMP_THREAD_ID=2
another parallel region: name:c005.local MPI_RANK_ID=0 OMP_THREAD_ID=0
another parallel region: name:c006.local MPI_RANK_ID=1 OMP_THREAD_ID=3
another parallel region: name:c005.local MPI_RANK_ID=0 OMP_THREAD_ID=3
another parallel region: name:c005.local MPI_RANK_ID=0 OMP_THREAD_ID=2
another parallel region: name:c006.local MPI_RANK_ID=1 OMP_THREAD_ID=0
another parallel region: name:c006.local MPI_RANK_ID=1 OMP_THREAD_ID=1
.
.
.
Here's the simple code:
#include <stdio.h>
#include "mpi.h"
#include <omp.h>
int main(int argc, char *argv[]) {
int numprocs, rank, namelen;
char processor_name[MPI_MAX_PROCESSOR_NAME];
int iam = 0, np = 1;
char name[MPI_MAX_PROCESSOR_NAME]; /* MPI_MAX_PROCESSOR_NAME ==
128 */
int O_ID; /* OpenMP thread ID
*/
int M_ID; /* MPI rank ID
*/
int rtn_val;
MPI_Init(&argc, &argv);
MPI_Comm_size(MPI_COMM_WORLD, &numprocs);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
MPI_Get_processor_name(processor_name, &namelen);
#pragma omp parallel default(shared) private(iam, np,O_ID)
{
np = omp_get_num_threads();
iam = omp_get_thread_num();
printf("Hello from thread %d out of %d from process %d out of %d on
%s\n",
iam, np, rank, numprocs, processor_name);
int i=0;
int j=0;
double counter=0;
for(i =0;i<99999999;i++)
{
O_ID = omp_get_thread_num(); /* get OpenMP
thread ID */
MPI_Get_processor_name(name,&namelen);
rtn_val = MPI_Comm_rank(MPI_COMM_WORLD,&M_ID);
printf("another parallel region: name:%s
MPI_RANK_ID=%d OMP_THREAD_ID=%d\n", name,M_ID,O_ID);
for(j = 0;j<999999999;j++)
{
counter=counter+i;
}
}
}
MPI_Finalize();
}
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Terry D. Dontje | Principal Software Engineer
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Oracle * - Performance Technologies*
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Email terry.don...@oracle.com <mailto:terry.don...@oracle.com>
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Developer Tools Engineering | +1.650.633.7054
Oracle * - Performance Technologies*
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Developer Tools Engineering | +1.650.633.7054
Oracle * - Performance Technologies*
95 Network Drive, Burlington, MA 01803
Email terry.don...@oracle.com <mailto:terry.don...@oracle.com>
