Fw: [Beowulf] large array to run

Thomas H Dr Pierce TPierce at rohmhaas.com
Fri Dec 14 20:07:24 EST 2007


beowulf-bounces at beowulf.org wrote on 12/13/2007 06:50:28 PM:

> This reminds me of a similar issue I had.  What approaches do you 
> take for large dense matrix multiplication in MPI, when the matrices
> are too large to fit into cluster memory?  If I hack up something to
> cache intermediate results to disk, the IO seems to drag everything 
> to a halt and I'm looking for a better solution.  I'd like to use 
> some libraries like PETSc, but how would you work around memory 
> limitations like this (short of building a bigger cluster)? 
> 

Dear Peter, 

There are many algorithms for Matrix operations that depend on the 
properties of the matrix and the operation.
You can easily add writing to a tmpfs RAM disk filesystem to speed methods 
that involve reading and writing of temporary files. 

So what I do now is take those old Fortran codes that read and write files 
and keep the intermediate result files in ramdisk. 

------
Sincerely,

   Tom Pierce
 


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