[Trilinos-Users] Best practice to modify elements of a Tpetra::Vector with openmp?
Wen Yan
wenyan4work at gmail.com
Fri May 12 17:36:42 EDT 2017
Hi Trilinos,
I was wondering what is the best practice to modify the elements of a Tpetra::Vector or a Tpetra::MultiVector. The document mentioned that ArrayRCP<T> is not thread safe, and suggested using Kokkos::View, but not much details are discussed. I am using Kokkos::OpenMP as the execution backend of Tpetra.
Assume xRcp is Teuchos::Rcp<Tpetra::MultiVector>
To use Kokkos::View, I can do this, but it is awkward and the Kokkos documentation does not include much useful information about these:
// auto x_2d = xRcp->getLocalView<Kokkos::HostSpace>();
// auto x_1d = Kokkos::subview(x_2d, Kokkos::ALL(), 0);
// xRcp->modify<Kokkos::HostSpace>();
// const size_t localLength = vecRcp->getLocalLength();
// #pragma omp parallel for
// for (size_t k = 0; k < localLength; ++k) {
// x_1d[k]=k;
// }
The ArrayRCP interface is more straightforward, but it is mentioned in the document that its reference counting is not compatible with multi threading. I was wondering if it is unsafe to write a simple for loop like this to modify the content of a Tpetra::Vector
// auto xArrayRcp = xRcp->getDataNonConst();
// const int localLength = xRcp->getLocalLength();
// #pragma omg parallel for
// for (int i = 0; i < localLength; i++) {
// xArrayRcp[i]=I;
// }
Thanks a lot!
Wen Yan
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