coll_tuned_reduce.c

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/*
 * Copyright (c) 2004-2005 The Trustees of Indiana University and Indiana
 *                         University Research and Technology
 *                         Corporation.  All rights reserved.
 * Copyright (c) 2004-2006 The University of Tennessee and The University
 *                         of Tennessee Research Foundation.  All rights
 *                         reserved.
 * Copyright (c) 2004-2005 High Performance Computing Center Stuttgart,
 *                         University of Stuttgart.  All rights reserved.
 * Copyright (c) 2004-2005 The Regents of the University of California.
 *                         All rights reserved.
 * $COPYRIGHT$
 *
 * Additional copyrights may follow
 *
 * $HEADER$
 */

#include "ompi_config.h"

#include "mpi.h"
#include "ompi/constants.h"
#include "ompi/datatype/datatype.h"
#include "ompi/communicator/communicator.h"
#include "ompi/mca/coll/coll.h"
#include "ompi/mca/coll/base/coll_tags.h"
#include "ompi/mca/pml/pml.h"
#include "ompi/op/op.h"
#include "coll_tuned.h"
#include "coll_tuned_topo.h"

/**
 * This is a generic implementation of the reduce protocol. It used the tree
 * provided as an argument and execute all operations using a segment of
 * count times a datatype.
 * For the last communication it will update the count in order to limit
 * th number of datatype to the original count (original_count)
 */
int ompi_coll_tuned_reduce_generic( void* sendbuf, void* recvbuf, int original_count,
                                    ompi_datatype_t* datatype, ompi_op_t* op,
                                    int root, ompi_communicator_t* comm,
                                    ompi_coll_tree_t* tree, int count_by_segment )
{
    char *inbuf[2] = {(char*)NULL, (char*)NULL};
    char *local_op_buffer = NULL, *accumbuf = NULL, *sendtmpbuf = NULL;
    ptrdiff_t extent, lower_bound;
    size_t typelng, realsegsize;
    ompi_request_t* reqs[2] = {MPI_REQUEST_NULL, MPI_REQUEST_NULL};
    int num_segments, line, ret, segindex, i, rank;
    int recvcount, prevcount, inbi, previnbi;

    /**
     * Determine number of segments and number of elements
     * sent per operation
     */
    ompi_ddt_get_extent( datatype, &lower_bound, &extent );
    ompi_ddt_type_size( datatype, &typelng );
    num_segments = (original_count + count_by_segment - 1) / count_by_segment;
    realsegsize = count_by_segment * extent;

    sendtmpbuf = (char*) sendbuf; 
    if( sendbuf == MPI_IN_PLACE ) { 
        sendtmpbuf = (char *)recvbuf; 
    }

    rank = ompi_comm_rank(comm);

    /* non-leaf nodes - wait for children to send me data & forward up (if needed) */
    if( tree->tree_nextsize > 0 ) {
        /* handle non existant recv buffer (i.e. its NULL) and 
           protect the recv buffer on non-root nodes */
        accumbuf = (char*)recvbuf;
        if( (NULL == accumbuf) || (root != rank) ) {
            accumbuf = (char*)malloc(realsegsize * num_segments);  /* TO BE OPTIMIZED */
	    if (accumbuf == NULL) { line = __LINE__; ret = -1; goto error_hndl; }
	} 

        /* Allocate two buffers for incoming segments */
        inbuf[0] = (char*) malloc(realsegsize);
        if( inbuf[0] == NULL ) { line = __LINE__; ret = -1; goto error_hndl; }
        /* if there is chance to overlap communication -
           allocate second buffer */
        if( (num_segments > 1) || (tree->tree_nextsize > 1) ) {
            inbuf[1] = (char*) malloc(realsegsize);
            if( inbuf[1] == NULL ) { line = __LINE__; ret = -1; goto error_hndl;}
        } else {
            inbuf[1] = NULL;
        }

        /* reset input buffer index and receive count */
        inbi = 0;
        recvcount = 0;
        /* for each segment */
        for( segindex = 0; segindex <= num_segments; segindex++ ) {
            prevcount = recvcount;
            /* recvcount - number of elements in current segment */
            recvcount = count_by_segment;
            if( segindex == (num_segments-1) )
                recvcount = original_count - count_by_segment * segindex;

            /* for each child */
            for( i = 0; i < tree->tree_nextsize; i++ ) {
                /**
                 * We try to overlap communication:
                 * either with next segment or with the next child
                 */
                /* post irecv for current segindex on current child */
                if( segindex < num_segments ) {
                    void* local_recvbuf = inbuf[inbi];
                    if( 0 == i ) {
                        /* for the first step (1st child per segment) we might be able to
                         * irecv directly into the accumulate buffer so that we can
                         * reduce(op) this with our sendbuf in one step as ompi_op_reduce
                         * only has two buffer pointers, this avoids an extra memory copy.
                         *
                         * BUT if we are root and are USING MPI_IN_PLACE this is wrong ek!
                         * check for root might not be needed as it should be checked higher up
                         */
                        if( !((MPI_IN_PLACE == sendbuf) && (rank == tree->tree_root)) ) {
                            local_recvbuf = accumbuf + segindex * realsegsize;
                        }
                    }
                    ret = MCA_PML_CALL(irecv(local_recvbuf, recvcount, datatype, tree->tree_next[i],
                                             MCA_COLL_BASE_TAG_REDUCE, comm, &reqs[inbi]));
                    if (ret != MPI_SUCCESS) { line = __LINE__; goto error_hndl;  }
                }
                /* wait for previous req to complete, if any */
                previnbi = (inbi+1) % 2;
                /* wait on data from last child for previous segment */
                ret = ompi_request_wait_all( 1, &reqs[previnbi], MPI_STATUSES_IGNORE );
                if (ret != MPI_SUCCESS) { line = __LINE__; goto error_hndl;  }
                local_op_buffer = inbuf[previnbi];
                if( i > 0 ) {
                    /* our first operation is to combine our own [sendbuf] data with the data
                     * we recvd from down stream (but only if we are not root and not using
                     * MPI_IN_PLACE)
                     */
                    if( 1 == i ) {
                        if( !((MPI_IN_PLACE == sendbuf) && (rank == tree->tree_root)) ) {
                            local_op_buffer = sendtmpbuf + segindex * realsegsize;
                        }
                    }
                    /* apply operation */
                    ompi_op_reduce(op, local_op_buffer, accumbuf+segindex*realsegsize, recvcount, datatype );
                } else if ( segindex > 0 ) {
                    void* accumulator = accumbuf + (segindex-1) * realsegsize;

                    if( tree->tree_nextsize <= 1 ) {
                        if( !((MPI_IN_PLACE == sendbuf) && (rank == tree->tree_root)) ) {            
                            local_op_buffer = sendtmpbuf+(segindex-1)*realsegsize;
                        }
                    }
                    ompi_op_reduce(op, local_op_buffer, accumulator, prevcount, datatype );

                    /* all reduced on available data this step (i) complete, pass to
                     * the next process unless your the root
                     */
                    if (rank != tree->tree_root) {
                        /* send combined/accumulated data to parent */
                        ret = MCA_PML_CALL( send( accumulator, prevcount, datatype,
                                                  tree->tree_prev, MCA_COLL_BASE_TAG_REDUCE,
                                                  MCA_PML_BASE_SEND_STANDARD, comm) );
                        if (ret != MPI_SUCCESS) { line = __LINE__; goto error_hndl;  }
                    }

                    /* we stop when segindex = number of segments (i.e. we do num_segment+1 steps to allow for pipelining */
                    if (segindex == num_segments) break;
                }

                /* update input buffer index */
                inbi = previnbi;
            } /* end of for each child */
        } /* end of for each segment */

        /* clean up */
        if( inbuf[0] != NULL) free(inbuf[0]);
        if( inbuf[1] != NULL) free(inbuf[1]);
        if( (NULL == recvbuf) || (root != rank) ) free(accumbuf);
    }

    /* leaf nodes */
    else {
        /* Send segmented data to parents */
        segindex = 0;
        while( original_count > 0 ) {
            if( original_count < count_by_segment ) count_by_segment = original_count;
            ret = MCA_PML_CALL( send((char*)sendbuf + segindex * realsegsize, count_by_segment,
                                     datatype, tree->tree_prev,
                                     MCA_COLL_BASE_TAG_REDUCE, MCA_PML_BASE_SEND_STANDARD, comm) );
            if (ret != MPI_SUCCESS) { line = __LINE__; goto error_hndl;  }
            segindex++;
            original_count -= count_by_segment;
        }
    }
    return OMPI_SUCCESS;

 error_hndl:  /* error handler */
    OPAL_OUTPUT (( ompi_coll_tuned_stream, "ERROR_HNDL: node %d file %s line %d error %d\n", rank, __FILE__, line, ret ));
    if( inbuf[0] != NULL ) free(inbuf[0]);
    if( inbuf[1] != NULL ) free(inbuf[1]);
    if( (NULL == recvbuf) && (NULL != accumbuf) ) free(accumbuf);
    return ret;
}

/* Attention: this version of the reduce operations does not
   work for:
   - non-commutative operations
   - segment sizes which are not multiplies of the extent of the datatype
     meaning that at least one datatype must fit in the segment !
*/

int ompi_coll_tuned_reduce_intra_chain( void *sendbuf, void *recvbuf, int count,
                                        ompi_datatype_t* datatype, ompi_op_t* op,
                                        int root, ompi_communicator_t* comm, uint32_t segsize,
                                        int fanout)
{
    int segcount = count;
    size_t typelng;

    OPAL_OUTPUT((ompi_coll_tuned_stream,"coll:tuned:reduce_intra_chain rank %d fo %d ss %5d", ompi_comm_rank(comm), fanout, segsize));

    COLL_TUNED_UPDATE_CHAIN( comm, root, fanout );
    /**
     * Determine number of segments and number of elements
     * sent per operation
     */
    ompi_ddt_type_size( datatype, &typelng );
    COLL_TUNED_COMPUTED_SEGCOUNT( segsize, typelng, segcount );

    return ompi_coll_tuned_reduce_generic( sendbuf, recvbuf, count, datatype, op, root, comm,
                                           comm->c_coll_selected_data->cached_chain, segcount );
}


int ompi_coll_tuned_reduce_intra_pipeline( void *sendbuf, void *recvbuf,
                                           int count, ompi_datatype_t* datatype,
                                           ompi_op_t* op, int root,
                                           ompi_communicator_t* comm, uint32_t segsize )
{
    int segcount = count;
    size_t typelng;

    OPAL_OUTPUT((ompi_coll_tuned_stream,"coll:tuned:reduce_intra_pipeline rank %d ss %5d",
                 ompi_comm_rank(comm), segsize));

    COLL_TUNED_UPDATE_PIPELINE( comm, root );

    /**
     * Determine number of segments and number of elements
     * sent per operation
     */
    ompi_ddt_type_size( datatype, &typelng );
    COLL_TUNED_COMPUTED_SEGCOUNT( segsize, typelng, segcount );

    return ompi_coll_tuned_reduce_generic( sendbuf, recvbuf, count, datatype, op, root, comm,
                                           comm->c_coll_selected_data->cached_pipeline, segcount );
}

int ompi_coll_tuned_reduce_intra_binary( void *sendbuf, void *recvbuf,
                                         int count, ompi_datatype_t* datatype,
                                         ompi_op_t* op, int root,
                                         ompi_communicator_t* comm, uint32_t segsize )
{
    int segcount = count;
    size_t typelng;

    OPAL_OUTPUT((ompi_coll_tuned_stream,"coll:tuned:reduce_intra_binary rank %d ss %5d",
                 ompi_comm_rank(comm), segsize));

    COLL_TUNED_UPDATE_BINTREE( comm, root );

    /**
     * Determine number of segments and number of elements
     * sent per operation
     */