On 10/30/2014 08:57 AM, Angel de Vicente wrote:
Set the MPI-IO hint "striping_unit" to the GPFS block size.
But this problem is happening when reading a file, not writing it
ah, it's right there in the subject. sorry about that.
>(in
any case, I have tried setting the striping_unit as well, but no
difference). So far I have no idea what is going on. ~1500 procs is
where the trouble begins, but the number of processors that breaks the
program is not fixed. I run it sucessfully with 1515 processors, then it
failed with 1480...
I suppose all one can do is get a backtrace from a few processors (by,
for example, attaching to a hung process with gdb) and see if you are
stuck in communication or if you are stuck in a case where the processes
are making very many teeny-tiny read operations (so not stuck, but
performing I/O so poorly as to be making imperceptible progress)
==rob
Any pointers appreciated,
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--
Rob Latham
Mathematics and Computer Science Division
Argonne National Lab, IL USA
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