thread_teams.cpp
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Created: Tue, Aug 27, 13:19

thread_teams.cpp
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	/*
	//@HEADER
	// ************************************************************************
	//
	// Kokkos v. 2.0
	// Copyright (2014) Sandia Corporation
	//
	// Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
	// the U.S. Government retains certain rights in this software.
	//
	// Redistribution and use in source and binary forms, with or without
	// modification, are permitted provided that the following conditions are
	// met:
	//
	// 1. Redistributions of source code must retain the above copyright
	// notice, this list of conditions and the following disclaimer.
	//
	// 2. Redistributions in binary form must reproduce the above copyright
	// notice, this list of conditions and the following disclaimer in the
	// documentation and/or other materials provided with the distribution.
	//
	// 3. Neither the name of the Corporation nor the names of the
	// contributors may be used to endorse or promote products derived from
	// this software without specific prior written permission.
	//
	// THIS SOFTWARE IS PROVIDED BY SANDIA CORPORATION "AS IS" AND ANY
	// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
	// PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL SANDIA CORPORATION OR THE
	// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
	// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
	// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
	// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
	// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
	// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
	// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	//
	// Questions? Contact H. Carter Edwards (hcedwar@sandia.gov)
	//
	// ************************************************************************
	//@HEADER
	*/

	#include <Kokkos_Core.hpp>
	#include <cstdio>

	// Using default execution space define a TeamPolicy and its member_type
	// The member_type is what the operator of a functor or Lambda gets, for
	// a simple RangePolicy the member_type is simply an integer
	// For a TeamPolicy its a much richer object, since it provides all information
	// to identify a thread uniquely and some team related function calls such as a
	// barrier (which will be used in a subsequent example).
	// A ThreadTeam consists of 1 to n threads where the maxmimum value of n is
	// determined by the hardware. On a dual socket CPU machine with 8 cores per socket
	// the maximum size of a team is 8. The number of teams (i.e. the league_size) is
	// not limited by physical constraints. Its a pure logical number.

	typedef Kokkos::TeamPolicy<> team_policy ;
	typedef team_policy::member_type team_member ;

	// Define a functor which can be launched using the TeamPolicy
	struct hello_world {
	typedef int value_type; //Specify value type for reduction target, sum

	// This is a reduction operator which now takes as first argument the
	// TeamPolicy member_type. Every member of the team contributes to the
	// total sum.
	// It is helpful to think of this operator as a parallel region for a team
	// (i.e. every team member is active and will execute the code).
	KOKKOS_INLINE_FUNCTION
	void operator() ( const team_member & thread, int& sum) const {
	sum+=1;
	// The TeamPolicy<>::member_type provides functions to query the multi
	// dimensional index of a thread as well as the number of thread-teams and the size
	// of each team.
	printf("Hello World: %i %i // %i %i\n",thread.league_rank(),thread.team_rank(),thread.league_size(),thread.team_size());
	}
	};

	int main(int narg, char* args[]) {
	Kokkos::initialize(narg,args);

	// Launch 12 teams of the maximum number of threads per team
	const team_policy policy( 12 , team_policy::team_size_max( hello_world() ) );

	int sum = 0;
	Kokkos::parallel_reduce( policy , hello_world() , sum );

	// The result will be 12*team_policy::team_size_max( hello_world())
	printf("Result %i\n",sum);

	Kokkos::finalize();
	}

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