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Merged
cedricchevalier19 merged 1 commit into from
Dec 8, 2025
+26 −0
Merged

feat(mpi): add non-blocking all-gather #192

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26 changes: 26 additions & 0 deletions src/KokkosComm/mpi/allgather.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -8,12 +8,38 @@

#include <KokkosComm/concepts.hpp>
#include <KokkosComm/traits.hpp>
#include "mpi_space.hpp"
#include "req.hpp"

#include "impl/types.hpp"
#include "impl/error_handling.hpp"

namespace KokkosComm::mpi {

template <KokkosExecutionSpace ExecSpace, KokkosView SView, KokkosView RView>
auto iallgather(const ExecSpace &space, const SView sv, RView rv, MPI_Comm comm) -> Req<Mpi> {
using ST = typename SView::non_const_value_type;
using RT = typename RView::non_const_value_type;
static_assert(std::is_same_v<ST, RT>, "KokkosComm::mpi::iallgather: View value types must be identical");
Kokkos::Tools::pushRegion("KokkosComm::mpi::iallgather");

fail_if(!is_contiguous(sv) || !is_contiguous(rv),
"KokkosComm::mpi::iallgather: unimplemented for non-contiguous views");

// Sync: Work in space may have been used to produce view data.
space.fence("fence before non-blocking all-gather");

Req<Mpi> req;
// All ranks send/recv same count
MPI_Iallgather(data_handle(sv), span(sv), Impl::mpi_type_v<ST>, data_handle(rv), span(sv), Impl::mpi_type_v<RT>, comm,
&req.mpi_request());
req.extend_view_lifetime(sv);
req.extend_view_lifetime(rv);

Kokkos::Tools::popRegion();
return req;
}

template <KokkosView SendView, KokkosView RecvView>
void allgather(const SendView &sv, const RecvView &rv, MPI_Comm comm) {
Kokkos::Tools::pushRegion("KokkosComm::Mpi::allgather");
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