[petsc-dev] refactoring petsccusp.h needed

[Karl Rupp]

Hi Paul,

> For GMRES, the current performance of VecMDot_SeqCUSP sucks. I have an
> solution, but I haven't tested all cases yet.
> For BCGS, some part of the algorithm is broken but I don't know what it
> is. By broken, I mean that CPU and GPU residuals diverge fairly quickly.

Since I just stumbled over VecMDot_SeqCUSP() when interfacing ViennaCL: 
Do you know what was the reason why the 'old' version was replaced by 
this expensive call to gemv() including the creation of temporaries, 
etc.? Just writing a custom kernel with one work group per dot-product 
should do the job perfectly, shouldn't it?

Best regards,
Karli