[petsc-dev] A closer look at the Xeon Phi

[Karl Rupp]

Hi Jed,

 >         Which crossover are you referring to? The CPU versus GTX285 at
>         about 20k
>         dofs, but with only very small gains for another order of magnitude?
>
>
>     I assume it's the cross-over of Xeon Phi vs. Xeon,
>
>
> MIC is slower than Xeon by more than an order of magnitude at 10k dofs.

Tim was referring to the cross-over at >10k...


>     but almost all cross-overs happen in the 10k-100k region and are due
>     to PCI-Express latency.
>
>
> Why is PCI-Express latency important here? Can't the MIC code run
> entirely on the device?

Almost-all (OpenCL, CUDA). Native mode ought to be the exception, but 
it's the OpenMP overhead which limits then. Single-core on the MIC is 
not really an option either...

It would be interesting to play with a pthreads-threadpool 
implementation on the MIC to see how much performance can really be 
obtained for smallish problems.

Best regards,
Karli