Re: [OMPI devel] System V Shared Memory for Open MPI: Request for Community Input and Testing

Hi all, Does anyone know of a relatively portable solution for querying a given system for the shmctl behavior that I am relying on, or is this going to be a nightmare? Because, if I am reading this thread correctly, the presence of shmget and Linux is not sufficient for determining an

Re: [OMPI devel] System V Shared Memory for Open MPI: Request for Community Input and Testing

On May 2 2010, Ashley Pittman wrote: On 2 May 2010, at 04:03, Samuel K. Gutierrez wrote: As to performance there should be no difference in use between sys-V shared memory and file-backed shared memory, the instructions issued and the MMU flags for the page should both be the same so the

Re: [OMPI devel] System V Shared Memory for Open MPI: Request for Community Input and Testing

On 02/05/10 06:49, Ashley Pittman wrote: > I think you should look into this a little deeper, it > certainly used to be the case on Linux that setting > IPC_RMID would also prevent any further processes from > attaching to the segment. That certainly appears to be the case in the current master

Re: [OMPI devel] System V Shared Memory for Open MPI: Request for Community Input and Testing

On 01/05/10 23:03, Samuel K. Gutierrez wrote: > I call shmctl IPC_RMID immediately after one process has > attached to the segment because, at least on Linux, this > only marks the segment for destruction. That's correct, looking at the kernel code (at least in the current git master) the

Re: [OMPI devel] System V Shared Memory for Open MPI: Request for Community Input and Testing

On 2 May 2010, at 04:03, Samuel K. Gutierrez wrote: > As far as I can tell, calling shmctl IPC_RMID is immediately destroying > the shared memory segment even though there is at least one process > attached to it. This is interesting and confusing because Solaris 10's > behavior description of

Re: [OMPI devel] System V Shared Memory for Open MPI: Request for Community Input and Testing

Hi Ethan, Sorry about the lag. As far as I can tell, calling shmctl IPC_RMID is immediately destroying the shared memory segment even though there is at least one process attached to it. This is interesting and confusing because Solaris 10's behavior description of shmctl IPC_RMID is similar to

Re: [OMPI devel] System V Shared Memory for Open MPI: Request for Community Input and Testing

Hi Ethan, Bummer. What does the following command show? sysctl -a | grep shm Thanks! -- Samuel K. Gutierrez Los Alamos National Laboratory On Apr 29, 2010, at 1:32 PM, Ethan Mallove wrote: Hi Samuel, I'm trying to run off your HG clone, but I'm seeing issues with c_hello, e.g., $

Re: [OMPI devel] System V Shared Memory for Open MPI: Request for Community Input and Testing

Hi, Faster component initialization/finalization times is one of the main motivating factors of this work. The general idea is to get away from creating a rather large backing file. With respect to module bandwidth and latency, mmap and sysv seem to be comparable - at least that is

Re: [OMPI devel] System V Shared Memory for Open MPI: Request for Community Input and Testing

On Tue, Apr 27, 2010 at 7:55 PM, Samuel K. Gutierrez wrote: > With Jeff and Ralph's help, I have completed a System V shared memory > component for Open MPI. What is the motivation for this work ? Are there situations where the mmap based SM component doesn't work or is slow(er)

[OMPI devel] System V Shared Memory for Open MPI: Request for Community Input and Testing

Hi, With Jeff and Ralph's help, I have completed a System V shared memory component for Open MPI. I have conducted some preliminary tests on our systems, but would like to get test results from a broader audience. As it stands, mmap is the defaul, but System V shared memory can be