[petsc-users] questions about vectorization

[Xiangdong]

1) How about the vectorization of BAIJ format? If the block size s is 2 or
4, would it be ideal for AVXs? Do I need to do anything special (more than
AVX flag) for the compiler to vectorize it?

2) Could you please update the linear solver table to label the
preconditioners/solvers compatible with ELL format?
http://www.mcs.anl.gov/petsc/documentation/linearsolvertable.html

Thank you.

Xiangdong

On Mon, Nov 13, 2017 at 11:32 AM, Zhang, Hong <hongzhang at anl.gov> wrote:

> Most operations in PETSc would not benefit much from vectorization since
> they are memory-bounded. But this does not discourage you from compiling
> PETSc with AVX2/AVX512. We have added a new matrix format (currently named
> ELL, but will be changed to SELL shortly) that can make MatMult ~2X faster
> than the AIJ format. The MatMult kernel is hand-optimized with AVX
> intrinsics. It works on any Intel processors that support AVX or AVX2 or
> AVX512, e.g. Haswell, Broadwell, Xeon Phi, Skylake. On the other hand, we
> have been optimizing the AIJ MatMult kernel for these architectures as
> well. And one has to use AVX compiler flags in order to take advantage of
> the optimized kernels and the new matrix format.
>
> Hong (Mr.)
>
> > On Nov 12, 2017, at 10:35 PM, Xiangdong <epscodes at gmail.com> wrote:
> >
> > Hello everyone,
> >
> > Can someone comment on the vectorization of PETSc? For example, for the
> MatMult function, will it perform better or run faster if it is compiled
> with avx2 or avx512?
> >
> > Thank you.
> >
> > Best,
> > Xiangdong
>
>
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