[OMPI users] Regarding Fortran 90 subroutines with MPI
Hi, I have encountered some run time errors in the general purpose program given below. Could you please assist me in correcting this. The MPI code is written in Fortran 90. The concept of subroutine is used because I want to write program for another scientific problem. module data use mpi implicit none integer::np, ierr, irank end module program prog use data implicit none integer::trial, ntrials ntrials=10 do trial=1, ntrials call mpi_comm_rank(mpi_comm_world, irank, ierr) call mpi_comm_size(mpi_comm_world,np, ierr) write(1, *) 'trial no=', trial write(1, *) 'irank np' call process !subroutine call end do print*,'Program completed!' call mpi_finalize(ierr) end subroutine process !subroutine use data implicit none if(irank.eq.0) then write(10, *) irank, np end if end subroutine process Could you please run the program and let e know the error? Thanking you Sincerely, Arun -- ** Arunkumar C R Research Assistant Solid State & Structural Chemistry Unit Indian Institute of Science Bangalore -12, INDIA arunkumar...@sscu.iisc.ernet.in Mob: +91- 9900 549 059 **
Re: [OMPI users] Regarding Fortran 90 subroutines with MPI
It would help if you would include the error messages you encounter. You need to call MPI_Init(ierr) before you can call (just about) any other MPI call. E.g., add "call MPI_Init(ierr)" as the first executable statement of your "program prog". The error I get with your program is *** An error occurred in MPI_Comm_f2c *** before MPI was initialized *** MPI_ERRORS_ARE_FATAL (your MPI job will now abort) I suppose that message could be clearer. If I add the MPI_Init call, things work fine. Arunkumar C R wrote: I have encountered some run time errors in the general purpose program given below. Could you please assist me in correcting this. The MPI code is written in Fortran 90. The concept of subroutine is used because I want to write program for another scientific problem. module data use mpi implicit none integer::np, ierr, irank end module program prog use data implicit none integer::trial, ntrials insert "call mpi_init(ierr)" here ntrials=10 do trial=1, ntrials call mpi_comm_rank(mpi_comm_world, irank, ierr) call mpi_comm_size(mpi_comm_world,np, ierr) write(1, *) 'trial no=', trial write(1, *) 'irank np' call process !subroutine call end do print*,'Program completed!' call mpi_finalize(ierr) end subroutine process !subroutine use data implicit none if(irank.eq.0) then write(10, *) irank, np end if end subroutine process Could you please run the program and let e know the error?
Re: [OMPI users] Regarding Fortran 90 subroutines with MPI
Arun, Before you call any MPI subroutines, you have to call MPI_Init(ierr) first. Once you put that line in, it should work. Cheers, Ethan -- Dr. Ethan Deneault Assistant Professor of Physics SC 234 University of Tampa Tampa, FL 33606 -Original Message- From: users-boun...@open-mpi.org on behalf of Arunkumar C R Sent: Thu 12/31/2009 1:29 AM To: us...@open-mpi.org Subject: [OMPI users] Regarding Fortran 90 subroutines with MPI Hi, I have encountered some run time errors in the general purpose program given below. Could you please assist me in correcting this. The MPI code is written in Fortran 90. The concept of subroutine is used because I want to write program for another scientific problem. module data use mpi implicit none integer::np, ierr, irank end module program prog use data implicit none integer::trial, ntrials ntrials=10 do trial=1, ntrials call mpi_comm_rank(mpi_comm_world, irank, ierr) call mpi_comm_size(mpi_comm_world,np, ierr) write(1, *) 'trial no=', trial write(1, *) 'irank np' call process !subroutine call end do print*,'Program completed!' call mpi_finalize(ierr) end subroutine process !subroutine use data implicit none if(irank.eq.0) then write(10, *) irank, np end if end subroutine process Could you please run the program and let e know the error? Thanking you Sincerely, Arun -- ** Arunkumar C R Research Assistant Solid State & Structural Chemistry Unit Indian Institute of Science Bangalore -12, INDIA arunkumar...@sscu.iisc.ernet.in Mob: +91- 9900 549 059 ** <>
Re: [OMPI users] Regarding Fortran 90 subroutines with MPI
Eugene Loh wrote: It would help if you would include the error messages you encounter. You need to call MPI_Init(ierr) before you can call (just about) any other MPI call. E.g., add "call MPI_Init(ierr)" as the first executable statement of your "program prog". The error I get with your program is *** An error occurred in MPI_Comm_f2c *** before MPI was initialized *** MPI_ERRORS_ARE_FATAL (your MPI job will now abort) I suppose that message could be clearer. I filed a request for a "minor enhancement". See https://svn.open-mpi.org/trac/ompi/ticket/2152
Re: [OMPI users] OpenMPI problem on Fedora Core 12
First of all, the reason that I have created a CPU-friendly version of MPI_Barrier is that my program is asymmetric (so some of the nodes can easily have to wait for several hours) and that it is I/O bound. My program uses MPI mainly to synchronize I/O and to share some counters between the nodes, followed by a gather/scatter of the files. MPI_Barrier (or any of the other MPI calls) caused the four CPU's of my Quad Core to continuously run at 100% because of the aggressive polling, making the server almost unusable and also slowing my program down because there was less CPU time available for I/O and file synchronization. With this version of MPI_Barrier CPU usage averages out at about 25%. I only recently learned about the OMPI_MCA_mpi_yield_when_idle variable, I still have to test if that is an alternative to my workaround. Meanwhile I seem to have found the cause of problem thanks to Ashley's excellent padb tool. Following Eugene's recommendation, I have added the MPI_Wait call: the same problem. Next I created a separate program that just calls my_barrier repeatedly with randomized 1-2 seconds intervals. Again the same problem (with 4 nodes), sometimes after a couple of iterations, sometimes after 500, 1000 or 2000 iterations. Next I followed Ashley's suggestion to use padb. I ran padb --all --mpi-queue and padb --all --message-queue while the program was running fine and after the problem occured. When the problem occurred padb said: Warning, remote process state differs across ranks state : ranks R : [2-3] S : [0-1] and $ padb --all --stack-trace --tree Warning, remote process state differs across ranks state : ranks R : [2-3] S : [0-1] - [0-1] (2 processes) - main() at ?:? barrier_util() at ?:? my_sleep() at ?:? __nanosleep_nocancel() at ?:? - [2-3] (2 processes) - ??() at ?:? ??() at ?:? ??() at ?:? ??() at ?:? ??() at ?:? ompi_mpi_signed_char() at ?:? ompi_request_default_wait_all() at ?:? opal_progress() at ?:? - 2 (1 processes) - mca_pml_ob1_progress() at ?:? suggests that rather than OpenMPI being the problem, nanosleep is the culprit because the call to it seems to hang. Thanks for all the help. Gijsbert On Mon, Dec 14, 2009 at 8:22 PM, Ashley Pittman wrote: > On Sun, 2009-12-13 at 19:04 +0100, Gijsbert Wiesenekker wrote: > > The following routine gives a problem after some (not reproducible) > > time on Fedora Core 12. The routine is a CPU usage friendly version of > > MPI_Barrier. > > There are some proposals for Non-blocking collectives before the MPI > forum currently and I believe a working implementation which can be used > as a plug-in for OpenMPI, I would urge you to look at these rather than > try and implement your own. > > > My question is: is there a problem with this routine that I overlooked > > that somehow did not show up until now > > Your code both does all-to-all communication and also uses probe, both > of these can easily be avoided when implementing Barrier. > > > Is there a way to see which messages have been sent/received/are > > pending? > > Yes, there is a message queue interface allowing tools to peek inside > the MPI library and see these queues. That I know of there are three > tools which use this, either TotalView, DDT or my own tool, padb. > TotalView and DDT are both full-featured graphical debuggers and > commercial products, padb is a open-source text based tool. > > Ashley, > > -- > > Ashley Pittman, Bath, UK. > > Padb - A parallel job inspection tool for cluster computing > http://padb.pittman.org.uk > > ___ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users >
