[petsc-dev] PCASM+KSPGMRES

[Karl Rupp]

Hi Andrea,

 > sorry to bother you with this again, but can you please give me a final
> word on whether KSPGMRES in combination with PCASM is currently supposed
> or not to work with MATMPIAIJCUSP on multiple-GPUs as it does (that I
> can clearly see) on 1 GPU? Do you have a test for that?

There are certainly examples around which allow this functionality, but 
multi-GPU algorithms are not routinely tested yet.


> Again, for what I can see, residuals are inconsistent with 1 or more
> GPUs and you don't get the same discrepancy with, for instance, PCJACOBI
> (same exact residuals on single and multi-GPU). This makes me think
> (maybe wrongly) that my part of the interfacing with PETSc is right.

Do you happen to have a simple example to reproduce? Which runtime 
options do you use/set? I'll try to reproduce this tomorrow.

Best regards,
Karli