[Trilinos-Users] Sparse matrix-vector multiplication with Tpetra::CrsMatrix and MKL

[Christopher Thiele]

Hello all,

I ported a PDE solver to Trilinos and did some performance evaluations. The
most demanding part are PCG solves, as expected. However, especially during
the sparse matrix-vector products (SPMV) some OpenMP threads are spinning a
lot and this is getting worse when the number of threads is increased. To
my understanding, the SPMV does not require any synchronization or
communication between the threads, so I can't see a reason for this
behavior.

Also, apparently the SPMV does not use the Intel MKL. Instead the method
spmv_alpha_beta_no_transpose() from
packages/tpetra/kernels/src/impl/Kokkos_Sparse_impl_spmv.hpp is being used.
Is there a way to change that?

Kind regards,
Christopher
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