I am observing a very strange performance issue with my openmpi program.

 

I have compute intensive openmpi based application that keeps the data in memory, process the data and then dumps it to GPFS parallel file system. GPFS parallel file system server is connected to a QDR infiniband switch from Voltaire.

 

If my cluster is connected to a DDR infiniband switch which in turn connects to file system server on QDR switch, I see that I can run my application under checkpoint/restart control (with –am ft-enable-cr) and I can checkpoint (ompi-checkpoint) successfully and the application gets completed after few additional seconds.

 

If my cluster is connected to the same QDR switch which connects to file system server, I see that my application takes close to 10x time to complete if I run it under checkpoint/restart control (with –am ft-enable-cr). If I run the same application using a plain mpirun command (ie; without -am ft_enable_cr), it finishes within a minute.

 

I am using open mpi 1.3.4 and BLCR 0.8.2 for checkpointing

 

Are there any specific MCA parameters that I should tune to address this problem? Any other pointers will be really helpful.

 

Thanks

Anand

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