[petsc-users] GAMG processor reduction

[Dave May]

Is using the "big communicator" really the right way to go? What happens
when I call VecNorm() when the local size on most ranks =0.. the global
reduction still has to be performed and all ranks in the original
communicator associated with the fine get participate.

I thought the primary advantage/reason to use less ranks with small
distributed systems was to avoid seeing the network latency when there is
little computational work. I don't see how using the big communicator
avoids this.

Am I missing something?

Cheers,
  Dave

On Thursday, 21 November 2013, Jed Brown wrote:

> John Mousel <john.mousel at gmail.com <javascript:;>> writes:
>
> > Thanks Jed. How does this represent itself in the KSPView output?
>
> I'm afraid it's not there, though you can extract the ownership ranges
> From code.
>
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