[petsc-dev] PCASM+KSPGMRES

[Andrea Lani]

Thanks a lot Karl!

Well, I don't usually use PETSc  runtime options. I have only a subset of parameters (PC types, KSP types, etc.) which are interfaced by my solver and exposed to the end-user. Other few settings (matrix types for instance) are hardcoded in some objects (which my linear system solver interface makes use of).

I can setup a testcase, but it cannot be too simple. You'll have to install my code to run it. I can setup a script for this. If you want to give it a try, I'll send you some instructions tomorrow (here is night already).

Best regards

Andrea




On Jan 21, 2014, at 10:38 PM, Karl Rupp <rupp at mcs.anl.gov> wrote:

> 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
>