[mpich-discuss] Internal memory allocation error?

[Brian Harker]

Hi Rajeev and list-

Well, nevermind, I think I found what was causing the trouble.  There
was an MPI_Bcast inside a loop when it shouldn't have been.  I'm not
exactly sure why this would conflict with the MPI_Recv for the pixel
coordinates, but removing the broadcast seems to fix it since it's
running to completion now.  Wow, that was pretty embarassing.  ;)
Thanks for the input though.  Especially thanks to Gib, since his
suggestion has cut down the number of sends by about 200K (!)

On Mon, Oct 20, 2008 at 12:44 PM, Rajeev Thakur <thakur at mcs.anl.gov> wrote:
> Can you send us a small program that we can run to reproduce the error?
>
> Rajeev
>
>> -----Original Message-----
>> From: owner-mpich-discuss at mcs.anl.gov
>> [mailto:owner-mpich-discuss at mcs.anl.gov] On Behalf Of Brian Harker
>> Sent: Monday, October 20, 2008 12:22 PM
>> To: mpich-discuss at mcs.anl.gov
>> Subject: Re: [mpich-discuss] Internal memory allocation error?
>>
>> Hi Rajeev-
>>
>> Yes, the sends and receives are in lock-step.  The code
>> finishes a pixel, then the master sends out the next
>> available pixel to the slave that just returned a result, but
>> during the slave's MPI_Recv to receive that next available
>> pixel is where the original error comes up.  I know, I
>> couldn't imagine how it would fail either, but lo and behold
>> my imagination isn't as good as the MPI error conditions  :)
>>
>> Hi Peter-
>>
>> I'm just running my code on a single workstation with a
>> dual-core processor.  The messages where the code fails are
>> just 2-element integer arrays, so my messages aren't large by
>> any standards, and I'd been thinking too about the large
>> number of sends/receives being the problem.  I too have tried
>> decreasing the message size while increasing the number of
>> sends/receives, but still to no avail.
>>
>>
>> --
>> Cheers,
>> Brian
>> brian.harker at gmail.com
>>
>>
>> "In science, there is only physics; all the rest is stamp-collecting."
>>
>> -Ernest Rutherford
>>
>>
>
>



-- 
Cheers,
Brian
brian.harker at gmail.com


"In science, there is only physics; all the rest is stamp-collecting."

-Ernest Rutherford