[Beowulf] MPICH vs MPICH2

[Robert Latham]

On Thu, Apr 07, 2005 at 03:30:09PM +0800, John Lau wrote:
> Hi,
> 
> Does anyone compare the different between MPICH and MPICH2? What are the
> greatest new features in MPICH2? And does the MPICH2 have large
> performance increase than MPICH? I would like to see some benchmarks
> that compare them.

Well, the foremost differnce between MPICH and MPICH2 is that MPICH2
implementes MPI-2, whereas MPICH implmented only MPI-1 and MPI-IO.  

MPICH2 has improved datatype handling routines 

	R. Ross, N. Miller, and W. Gropp, "Implementing Fast and
	Reusable Datatype Processing," Proceedings of EuroPVM/MPI
	2003, Venice, Italy, September, 2003.

MPICH2 has excellent performance for one-sided opeerations.  Hard to
compare with MPICH on this one, but there are benchmarks where MPICH2  
compares favorably with other MPI-2 implementations.

	R. Thakur, W. Gropp, and B. Toonen, "Minimizing
	Synchronization Overhead in the Implementation of MPI
	One-Sided Communication", Proceedings of the 11th European
	PVM/MPI Users' Group Conference (Euro PVM/MPI 2004), September
	2004.

I can't find the data to back this up but MPICH2 does perform better
than MPICH1 in point-to-point messaging (as measured by NetPIPE).  28%
faster for an 8MB message.  

I hope that's enough to entice you into trying MPICH2.  I work with
the MPICH2 folks, so I'm a little biased, but it's a quality
implementation.

==rob

-- 
Rob Latham
Mathematics and Computer Science Division    A215 0178 EA2D B059 8CDF
Argonne National Labs, IL USA                B29D F333 664A 4280 315B