[Beowulf] OS for 64 bit AMD

Mike Davis jmdavis at mail2.vcu.edu
Tue Apr 5 00:31:44 EDT 2005


Joe,
Thanks. I am running PG, ABsoft, intel, and gnu compilers on my variety 
of clusters and smp machines. The move to an f95 makes sense overall. 
But, you might not believe just how much f77 and earlier code (ported to 
f77) is still in use. It's not unusual to have someone come by the 
office once or twice a semester with some code that is f77 or Fortran 4 
and want to know if it can run on one of the clusters. Then, of course, 
we have the whole parallelization discussion. "No it won't just work as 
a parallel program. Yes we might be able to get some speedup with 
automated tools and loop unrolling. No the speedup won't be linear, 1+1 
will not equal 2 for this case. The best speedup would come from a 
rewrite for mpi, etc. etc. "

thanks again,

Mike

Joe Landman wrote:

>
>
> Mike Davis wrote:
>
>> What are the good reasons not to have g77 in gcc4? I admit ignorance 
>> on the subject of gcc4, but g77 is useful to many in the scientific 
>> and academic communities.
>
>
> Hi Mike:
>
>   g77 does not work with the tree-ssa branch that gcc4 is emerging/has 
> emerged from (please correct me if I am wrong about the details on 
> this Greg/Toon/others).  gfortran is going to take its place (again 
> please correct me if this statement is not correct).  c.f. 
> http://gcc.gnu.org/develop.html and related and the mailing list 
> archives at http://gcc.gnu.org/ml/fortran/ and 
> http://gcc.gnu.org/fortran/ .  The idea is that gfortran is a f95 
> compiler to supplant g77 (an f77 + some f90 extensions) due in large 
> part to the issues in carrying forward a pure f77 compiler when many 
> in the fortran world are at/beyond f95.  That is, fortran will be 
> available, but the compiler appears to be an f95 compiler going forward.
>
>   That said, there are excellent commercial compilers available from 
> Greg's company (PathScale), the Portland Group (been playing with 
> v6.0), Intel for their processors, and others on the x86/AMD64/IA64 
> stream. For those of the PPC persuasion, the IBM compilers are quite 
> good.
>
> Joe
>


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