[mpich-discuss] MP_EAGER_LIMIT and MP_BUFFER_MEM question

[Matthew Niemerg]

Jeff,

Here's a quick mpi program that reproduces the problem.  All you do is
enter in some # of bytes that you want to pass (to test what is the max
size of an array).  The max on my machine is 6000 (i.e. 5999 works, but
6000 doesn't).  I am not sure why that would be the limit.  Anyway, the
output on my machine indicates the null terminating character isn't sent,
or the entire array was not able to be passed.  Regardless, perplexed by
this issue.

I am, however, able to pass larger arrays (I went up to 8381153)
successfully, but still get some garbage data at the very end (i.e.,
outputting the character array to the console is fine, except the last byte
which outputs as : ??_?).

FYI, the machine I am using is a Mac 10.6.8, and am using mpich2.1.3 with
the x86_64 architecture.

Matt

On Wed, Nov 7, 2012 at 3:10 PM, Jeff Hammond <jhammond at alcf.anl.gov> wrote:

> Unless you're on a BGQ or IBM machine with LoadLeveler, I don't see
> how those variables can have any impact on the execution of your code.
>
> cc:mpich2-trunk jhammond$ grep MP_EAGER_LIMIT * -R
> src/mpid/pamid/src/mpidi_env.c:    char* names[] = {"PAMID_EAGER",
> "PAMID_RZV", "MP_EAGER_LIMIT", "PAMI_RVZ", "PAMI_RZV", "PAMI_EAGER",
> NULL};
> src/mpid/pamid/src/mpidi_env.c:    char* names[] = {"PAMID_RZV_LOCAL",
> "PAMID_EAGER_LOCAL", "MP_EAGER_LIMIT_LOCAL", "PAMI_RVZ_LOCAL",
> "PAMI_RZV_LOCAL", "PAMI_EAGER_LOCAL", NULL};
> src/mpid/pamid/src/mpidi_util.c:
> MATCHI(eager_limit,"Message Eager Limit (MP_EAGER_LIMIT/Bytes):");
> src/pm/hydra/tools/bootstrap/external/ll_env.c:
> "MP_DEBUG_INITIAL_STOP", "MP_DEBUG_LOG", "MP_EAGER_LIMIT",
>
> Can you provide a test code that exercises the problem to which you allude?
>
> Thanks,
>
> Jeff
>
> On Wed, Nov 7, 2012 at 4:53 PM, Matthew Niemerg
> <niemerg at math.colostate.edu> wrote:
> > Hello,
> >
> > I'm developing a parallel program and have run into MPI hanging on jobs.
> > I've narrowed the problem down to broadcasting data to other nodes.  I am
> > curious how to get a hold of and set the environment variables
> > MP_EAGER_LIMIT and MP_BUFFER_MEM.  We need to be able to adjust our code
> > based off of individual machine's configurations of MPI, which is why I
> need
> > to get what the environment variables are.  I tried to use the
> > getenv("MP_EAGER_LIMIT") call, but that seemed to fail.  In addition,
> I've
> > tried to set these environment variables using the export command in the
> > shell before running my program, but that doesn't seem to work either.
> >
> > Are these environment variables set at runtime, during the configuration
> of
> > mpich2, or what?  The data that is being passed is about 10 megs, which,
> I
> > wouldn't think would be an issue, but apparently is!
> >
> > Anyway, any help you can provide would be much appreciative.
> >
> > Sincerely,
> > Matthew Niemerg
> > Graduate Research Assistant
> > Mathematics Department
> > Colorado State University
> >
> > _______________________________________________
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> >
>
>
>
> --
> Jeff Hammond
> Argonne Leadership Computing Facility
> University of Chicago Computation Institute
> jhammond at alcf.anl.gov / (630) 252-5381
> http://www.linkedin.com/in/jeffhammond
> https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond
> _______________________________________________
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