Re: [OMPI users] How to start MPI_Spawn child processes early?
My question is why? If you are willing to reserve a chunk of your machine for yet-to-exist tasks, why not just create them all at mpirun time and slice and dice your communicators as appropriate? On Thu, 2010-01-28 at 09:24 +1100, Jaison Paul wrote: > Hi, I am just reposting my early query once again. If anyone one can > give some hint, that would be great. > > Thanks, Jaison > ANU > > Jaison Paul wrote: > > Hi All, > > > > I am trying to use MPI for scientific High Performance (hpc) > > applications. I use MPI_Spawn to create child processes. Is there a > > way to start child processes early than the parent process, using > > MPI_Spawn? > > > > I want this because, my experiments showed that the time to spawn the > > children by parent is too long for HPC apps which slows down the whole > > process. If the children are ready when parent application process > > seeks for them, that initial delay can be avoided. Is there a way to > > do that? > > > > Thanks in advance, > > > > Jaison > > Australian National University > > ___ > > users mailing list > > us...@open-mpi.org > > http://www.open-mpi.org/mailman/listinfo.cgi/users > > ___ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users
Re: [OMPI users] How to start MPI_Spawn child processes early?
It sounds to me a bit like asking to be born before your mother. Unless I misunderstand the question... Douglas. On Thu, Jan 28, 2010 at 09:24:29AM +1100, Jaison Paul wrote: > Hi, I am just reposting my early query once again. If anyone one can > give some hint, that would be great. > > Thanks, Jaison > ANU > > Jaison Paul wrote: >> Hi All, >> >> I am trying to use MPI for scientific High Performance (hpc) >> applications. I use MPI_Spawn to create child processes. Is there a >> way to start child processes early than the parent process, using >> MPI_Spawn? >> >> I want this because, my experiments showed that the time to spawn the >> children by parent is too long for HPC apps which slows down the whole >> process. If the children are ready when parent application process >> seeks for them, that initial delay can be avoided. Is there a way to >> do that? >> >> Thanks in advance, >> >> Jaison >> Australian National University
Re: [OMPI users] How to start MPI_Spawn child processes early?
I cannot resist: Jaison - The MPI_Comm_spawn call specifies what you want to have happen. The child launch is what does happen. If we can come up with a way to have things happen correctly before we know what it is that we want to have happen, the heck with this HPC stuff. Lets get together and place stock orders on yesterday's market. Just joking - Ralph's suggestion about launching all parts of the application up front and then using JOIN or ACCEPT/CONNECT will work. I also agree with his skepticism about the problem. Most applications that are worth running in parallel take long enough so the time it takes to spawn should be barely noticeable. Are you using parallelism for something that only takes a few seconds and if so, why not just do it with a serial run? Dick Treumann - MPI Team IBM Systems & Technology Group Dept X2ZA / MS P963 -- 2455 South Road -- Poughkeepsie, NY 12601 Tele (845) 433-7846 Fax (845) 433-8363 users-boun...@open-mpi.org wrote on 01/27/2010 06:07:43 PM: > [image removed] > > Re: [OMPI users] How to start MPI_Spawn child processes early? > > Ralph Castain > > to: > > Open MPI Users > > 01/27/2010 06:09 PM > > Sent by: > > users-boun...@open-mpi.org > > Please respond to Open MPI Users > > I can't imagine how you would do that - only thing I can think of > would be to start your "child" processes as one job, then start your > "parent" processes and have them do an MPI_Comm_join with the child job. > > That said, I can't imagine that comm_spawn is -that- slow to make > much difference to an HPC application! At least, not in anything > I've measured. > > On Jan 27, 2010, at 3:24 PM, Jaison Paul wrote: > > > Hi, I am just reposting my early query once again. If anyone one > can give some hint, that would be great. > > > > Thanks, Jaison > > ANU > > > > Jaison Paul wrote: > >> Hi All, > >> > >> I am trying to use MPI for scientific High Performance (hpc) > applications. I use MPI_Spawn to create child processes. Is there a > way to start child processes early than the parent process, using MPI_Spawn? > >> > >> I want this because, my experiments showed that the time to spawn > the children by parent is too long for HPC apps which slows down the > whole process. If the children are ready when parent application > process seeks for them, that initial delay can be avoided. Is there > a way to do that? > >> > >> Thanks in advance, > >> > >> Jaison > >> Australian National University > >> ___ > >> users mailing list > >> us...@open-mpi.org > >> http://www.open-mpi.org/mailman/listinfo.cgi/users > > > > ___ > > users mailing list > > us...@open-mpi.org > > http://www.open-mpi.org/mailman/listinfo.cgi/users > > > ___ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users
Re: [OMPI users] How to start MPI_Spawn child processes early?
I can't imagine how you would do that - only thing I can think of would be to start your "child" processes as one job, then start your "parent" processes and have them do an MPI_Comm_join with the child job. That said, I can't imagine that comm_spawn is -that- slow to make much difference to an HPC application! At least, not in anything I've measured. On Jan 27, 2010, at 3:24 PM, Jaison Paul wrote: > Hi, I am just reposting my early query once again. If anyone one can give > some hint, that would be great. > > Thanks, Jaison > ANU > > Jaison Paul wrote: >> Hi All, >> >> I am trying to use MPI for scientific High Performance (hpc) applications. I >> use MPI_Spawn to create child processes. Is there a way to start child >> processes early than the parent process, using MPI_Spawn? >> >> I want this because, my experiments showed that the time to spawn the >> children by parent is too long for HPC apps which slows down the whole >> process. If the children are ready when parent application process seeks for >> them, that initial delay can be avoided. Is there a way to do that? >> >> Thanks in advance, >> >> Jaison >> Australian National University >> ___ >> users mailing list >> us...@open-mpi.org >> http://www.open-mpi.org/mailman/listinfo.cgi/users > > ___ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users
Re: [OMPI users] How to start MPI_Spawn child processes early?
Hi, I am just reposting my early query once again. If anyone one can give some hint, that would be great. Thanks, Jaison ANU Jaison Paul wrote: Hi All, I am trying to use MPI for scientific High Performance (hpc) applications. I use MPI_Spawn to create child processes. Is there a way to start child processes early than the parent process, using MPI_Spawn? I want this because, my experiments showed that the time to spawn the children by parent is too long for HPC apps which slows down the whole process. If the children are ready when parent application process seeks for them, that initial delay can be avoided. Is there a way to do that? Thanks in advance, Jaison Australian National University ___ users mailing list us...@open-mpi.org http://www.open-mpi.org/mailman/listinfo.cgi/users
