i-node version of MatRelax()

Barry Smith bsmith at mcs.anl.gov
Mon Aug 6 16:31:54 CDT 2007


   There is a another thing we can do for the SSOR-CG in parallel, that is
write the code for Eisenstat's trick. This would save roughly 40 % of the 
flops in the MatMult/MatRelax() and require only one pass from memory of
the matrix entries, instead of the current two.

  It is a bit of work/debugging and testing, several good days. I don't 
know who has time.


On Sun, 5 Aug 2007, Dinesh Kaushik wrote:

> Barry,
> Thank you very much for the i-node version of MatRelax. I will test it out in
> a few days on Jaguar. Right now, I am busy writing the INCITE proposal for
> UNIC. This reminds me to ask you for a two page bio (in Word or pdf format).
> It can be very close to what you used for the SciDAC last year (see
> instructions at
> http://hpc.science.doe.gov/allocations/incite/instructions.do).
> I am able to run the full core mesh (33 groups) on up to 4096 processors with
> 57% efficiency (wrt 512 processors). The problem size (P3) per processor is
> quite small with 4096 subdomains. The higher orders will show better
> scalability but take too long to converge and getting thro' the queue has
> become very slow on Jaguar lately. We will discuss the Computational Readiness
> (scalability) section of the proposal before it gets submitted on Wednesday.
> Thanks,
> Dinesh
> Barry Smith wrote:
> >   Dinesh,
> > 
> >     I have completed and pushed to petsc-dev an i-node version of
> > MatRelax(). Please use this version in all your future runs with UNIC. It
> > should be a bit faster and maybe save a few iterations. Please let me know
> > how it performs. If you see worse or failed convergence
> > please let me know immediately so it can be debugged and fixed.
> > 
> >    Barry
> > 
> > This will have no affect on CFDShip since that code does not have i-nodes.
> > 

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