[Trilinos-Users] Parallel Performance and non-continuous block layout

Heroux, Michael A maherou at sandia.gov
Mon Oct 4 10:54:31 MDT 2010


Scot,

The performance difference continuous and non-continuous should be minimal,
for sufficiently large problems.

Regarding your last questions, I think Alan Williams can best answer it.  I
assume you are using the FECrsMatrix class, right?

Mike


On 10/4/10 11:29 AM, "M. Scot Breitenfeld" <brtnfld at uiuc.edu> wrote:

>   Does it effect the parallel performance to have non-continuous nodal
> global ordering? For example, in 1D if I have (2 procs),
> 
> 1    2    3   4    5   6   7   8
> o    o   o   o  | o   o   o  o
> 
> then the processors will have continuous blocks of rows (proc 0, 0-3:
> proc 1: 4-7) or the other case:
> 
> 1    4    5   8    3   6   7   2
> o    o   o   o  | o   o   o  o
> 
> where proc 0 has rows 0,3,4,7 and proc 1 has rows 2, 5, 7, 1.
> Also, my method requires nodes in the region past partition boundary
> (for example nodes 3,6,7 contribute to proc 0), not just the nodes
> directly adjacent to the partition boundary.
> 
> And another question, can I do my calculations for partition boundary
> nodes (nodes involved with communication) and then: call
> GlobalAssemble,  do the calculations for my interior nodes, and call
> FillComplete ?
> 
> Thanks,
> Scot
> 
> 
> 
> 
> 
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