[petsc-dev] [GPU - slepc] Hands-on exercise 4 (SVD) not working with GPU and default configurations

[Leoni, Massimiliano]

> -----Original Message-----
> From: Karl Rupp [mailto:rupp at iue.tuwien.ac.at]
> Sent: 10 August 2015 11:54
> To: Leoni, Massimiliano
> Cc: slepc-maint at upv.es; petsc-dev at mcs.anl.gov
> Subject: Re: [petsc-dev] [GPU - slepc] Hands-on exercise 4 (SVD) not working
> with GPU and default configurations

> The use of aijcusp instead of a dense matrix type certainly adds to the issue.
I know, but I couldn't find a dense gpu type in the petsc manual, please correct me if there is any.

> Please send the output of -log_summary so that we can see where most
> time is spent.
I am unable to do that as somehow I am having no output when I use that option. I also tried to explicitly call PetscLogView but still nothing is printed out.
If I try with one of the slepc examples, I get the output.
Why is this happening? If I run my code with -info or -log_trace I see their output, only -log_summary is shy!

> If you have good (recent) CPUs in dual-socket configuration, it's more than
> unlikely that you will gain anything beyond ~2x with an optimized GPU setup.
> Even that ~2x may only be possible with heavily tweaking the current SVD-
> implementation in SLEPc, of which I don't know the details.
I used Xeon processors from 2010, just like the GPUs.
This is not good news, as my supervisor is really optimist about using GPUs and getting high speed-ups!
Anyway, at the moment my gpu version is several times slower than the cpu version, so even a 2x would be a win now :D


Massimiliano
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