hpx/collectives/all_reduce.hpp

See Public API for a list of names and headers that are part of the public HPX API.

namespace hpx
namespace collectives

Functions

template<typename T, typename F>
hpx::future<std::decay_t<T>> all_reduce(char const *basename, T &&result, F &&op, num_sites_arg num_sites = num_sites_arg(), this_site_arg this_site = this_site_arg(), generation_arg generation = generation_arg(), root_site_arg root_site = root_site_arg())

AllReduce a set of values from different call sites

This function receives a set of values from all call sites operating on the given base name.

Return

This function returns a future holding a vector with all values send by all participating sites. It will become ready once the all_reduce operation has been completed.

Parameters
  • basename: The base name identifying the all_reduce operation

  • local_result: The value to transmit to all participating sites from this call site.

  • op: Reduction operation to apply to all values supplied from all participating sites

  • num_sites: The number of participating sites (default: all localities).

  • generation: The generational counter identifying the sequence number of the all_reduce operation performed on the given base name. This is optional and needs to be supplied only if the all_reduce operation on the given base name has to be performed more than once.

  • this_site: The sequence number of this invocation (usually the locality id). This value is optional and defaults to whatever hpx::get_locality_id() returns. \params root_site The site that is responsible for creating the all_reduce support object. This value is optional and defaults to ‘0’ (zero).

template<typename T, typename F>
hpx::future<std::decay_t<T>> all_reduce(communicator comm, T &&result, F &&op, this_site_arg this_site = this_site_arg())

AllReduce a set of values from different call sites

This function receives a set of values from all call sites operating on the given base name.

Return

This function returns a future holding a vector with all values send by all participating sites. It will become ready once the all_reduce operation has been completed.

Parameters
  • comm: A communicator object returned from create_communicator

  • local_result: The value to transmit to all participating sites from this call site.

  • op: Reduction operation to apply to all values supplied from all participating sites

  • this_site: The sequence number of this invocation (usually the locality id). This value is optional and defaults to whatever hpx::get_locality_id() returns.