[MITgcm-support] MITgcm on Sun Fire cluster

[William Aiken]

Abbas,

   Have you run other codes on both systems, or just MIT-gcm?  Certain 
codes scale better than others. Your results indicate scaling up to 4 
CPU's, then the overhead of MPI makes the performance worse. Another 
factor may be NUMA on the UltraSPARC-IV system.

Your relative clock speed (2.5 GHz vs 1.5 GHz) would result in 1.6 
speedup on the Intel system if other factors do not contribute.

Another factor is the compiler optimization used on each system.

Please check the optfile and see what the -O parameter is. You should 
have -O4 or -O5 set to get the best optimization. What version of Sun 
Studio are you using (or are you using gnu tools)?

Regards,

Bill


Abbas Dorostkar wrote:
> Hi all,
> 
>  
> 
> I have been running a test case -internal wave test case in 
> nonhydrostatic mode- with MPI on a SunFire cluster. Unfortunately, the 
> performance of the model on the cluster is terrible in comparison with 
> the same run on my desktop computer.
> 
> Here, I mentioned the wall clock times for both systems:
> 
> On the cluster , Sun Fire 2500 server with 72 (2 MB on-chip L2 cache and 
> 32 MB L3 cache)  dual-core UltraSPARC-IV+ 1.5 GHZ processors with 676 GB 
> of RAM:
> 
> serial-- > 457 s
> 
> np=2 -- > 353 s
> 
> np=4 -- > 275 s
> 
> np=6 -- > 315 s
> 
>  
> 
> On my Desktop (Intel core 2 Due - 2.4 GHZ - 4 MB cache - 1066 MHZ FSB ):
> 
> serial -- > 171 s
> 
> np=2 --->  162 s
> 
>  
> 
> I use the sunos_sun4u_mpf77+mpi_sunfire optfile shipped with the MITgcm 
> model (v 1.4 2007/02/18). I have to mention that I get following 
> warnings while I compile the model on the cluster:
> 
> make: Warning: Too many rules defined for target PACKAGES_CONFIG.h
> make: Warning: Too many rules defined for target AD_CONFIG.h
> make: Warning: Too many rules defined for target FC_NAMEMANGLE.h
> make: Warning: Too many rules defined for target BUILD_INFO.h
> 
>  
> 
> Does anyone  know what is going wrong? Should I change something in the 
> optfile (e.g adding some optimization flags)?
> 
>  
> 
> Your help is much appreciated!
> 
>  
> 
> Abbas
> 

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-- 
William Aiken          Sun Microsystems, Inc.
Phone: 781.442.3312    ISV Engineering
FAX: 781.442.1520      45 Network Drive UBUR01-204
                        Burlington, Massachusetts 01803