/* selector for collective algorithms based on openmpi's default coll_tuned_decision_fixed selector */

/* Copyright (c) 2009-2010, 2013. The SimGrid Team.
 * All rights reserved.                                                     */

/* This program is free software; you can redistribute it and/or modify it
 * under the terms of the license (GNU LGPL) which comes with this package. */

#include "colls_private.h"


int smpi_coll_tuned_allreduce_ompi(void *sbuf, void *rbuf, int count,
                        MPI_Datatype dtype, MPI_Op op, MPI_Comm comm)
{
    size_t dsize, block_dsize;
    int comm_size = smpi_comm_size(comm);
    const size_t intermediate_message = 10000;

    /**
     * Decision function based on MX results from the Grig cluster at UTK.
     * 
     * Currently, linear, recursive doubling, and nonoverlapping algorithms 
     * can handle both commutative and non-commutative operations.
     * Ring algorithm does not support non-commutative operations.
     */
    dsize = smpi_datatype_size(dtype);
    block_dsize = dsize * count;

    if (block_dsize < intermediate_message) {
        return (smpi_coll_tuned_allreduce_rdb (sbuf, rbuf, 
                                                                   count, dtype,
                                                                   op, comm));
    } 

    if( smpi_op_is_commute(op) && (count > comm_size) ) {
        const size_t segment_size = 1 << 20; /* 1 MB */
        if ((comm_size * segment_size >= block_dsize)) {
            //FIXME: ok, these are not the right algorithms, try to find closer ones
            // lr is a good match for allreduce_ring (difference is mainly the use of sendrecv)
            return smpi_coll_tuned_allreduce_lr(sbuf, rbuf, count, dtype,
                                              op, comm);
        } else {
           return (smpi_coll_tuned_allreduce_ompi_ring_segmented (sbuf, rbuf,
                                                                    count, dtype, 
                                                                    op, comm 
                                                                    /*segment_size*/));
        }
    }

    return (smpi_coll_tuned_allreduce_redbcast(sbuf, rbuf, count, 
                                                            dtype, op, comm));
}



int smpi_coll_tuned_alltoall_ompi( void *sbuf, int scount, 
                                             MPI_Datatype sdtype,
                                             void* rbuf, int rcount, 
                                             MPI_Datatype rdtype, 
                                             MPI_Comm comm)
{
    int communicator_size;
    size_t dsize, block_dsize;
    communicator_size = smpi_comm_size(comm);

    /* Decision function based on measurement on Grig cluster at 
       the University of Tennessee (2GB MX) up to 64 nodes.
       Has better performance for messages of intermediate sizes than the old one */
    /* determine block size */
    dsize = smpi_datatype_size(sdtype);
    block_dsize = dsize * scount;

    if ((block_dsize < 200) && (communicator_size > 12)) {
        return smpi_coll_tuned_alltoall_bruck(sbuf, scount, sdtype, 
                                                    rbuf, rcount, rdtype,
                                                    comm);

    } else if (block_dsize < 3000) {
        return smpi_coll_tuned_alltoall_basic_linear(sbuf, scount, sdtype, 
                                                           rbuf, rcount, rdtype, 
                                                           comm);
    }

    return smpi_coll_tuned_alltoall_ring (sbuf, scount, sdtype, 
                                                    rbuf, rcount, rdtype,
                                                    comm);
}

int smpi_coll_tuned_alltoallv_ompi(void *sbuf, int *scounts, int *sdisps,
                                              MPI_Datatype sdtype,
                                              void *rbuf, int *rcounts, int *rdisps,
                                              MPI_Datatype rdtype,
                                              MPI_Comm  comm
                                              )
{
    /* For starters, just keep the original algorithm. */
    return smpi_coll_tuned_alltoallv_ompi_basic_linear(sbuf, scounts, sdisps, sdtype, 
                                                        rbuf, rcounts, rdisps,rdtype,
                                                        comm);
}


int smpi_coll_tuned_barrier_ompi(MPI_Comm  comm)
{    int communicator_size = smpi_comm_size(comm);

    if( 2 == communicator_size )
        return smpi_coll_tuned_barrier_ompi_two_procs(comm);
/*     * Basic optimisation. If we have a power of 2 number of nodes*/
/*     * the use the recursive doubling algorithm, otherwise*/
/*     * bruck is the one we want.*/
    {
        int has_one = 0;
        for( ; communicator_size > 0; communicator_size >>= 1 ) {
            if( communicator_size & 0x1 ) {
                if( has_one )
                    return smpi_coll_tuned_barrier_ompi_bruck(comm);
                has_one = 1;
            }
        }
    }
    return smpi_coll_tuned_barrier_ompi_recursivedoubling(comm);
}

int smpi_coll_tuned_bcast_ompi(void *buff, int count,
                                          MPI_Datatype datatype, int root,
                                          MPI_Comm  comm
                                          )
{
    /* Decision function based on MX results for 
       messages up to 36MB and communicator sizes up to 64 nodes */
    const size_t small_message_size = 2048;
    const size_t intermediate_message_size = 370728;
    const double a_p16  = 3.2118e-6; /* [1 / byte] */
    const double b_p16  = 8.7936;   
    const double a_p64  = 2.3679e-6; /* [1 / byte] */
    const double b_p64  = 1.1787;     
    const double a_p128 = 1.6134e-6; /* [1 / byte] */
    const double b_p128 = 2.1102;

    int communicator_size;
    //int segsize = 0;
    size_t message_size, dsize;

    communicator_size = smpi_comm_size(comm);

    /* else we need data size for decision function */
    dsize = smpi_datatype_size(datatype);
    message_size = dsize * (unsigned long)count;   /* needed for decision */

    /* Handle messages of small and intermediate size, and 
       single-element broadcasts */
    if ((message_size < small_message_size) || (count <= 1)) {
        /* Binomial without segmentation */
        return  smpi_coll_tuned_bcast_binomial_tree (buff, count, datatype, 
                                                      root, comm);

    } else if (message_size < intermediate_message_size) {
        // SplittedBinary with 1KB segments
        return smpi_coll_tuned_bcast_ompi_split_bintree(buff, count, datatype, 
                                                         root, comm);

    }
     //Handle large message sizes 
    else if (communicator_size < (a_p128 * message_size + b_p128)) {
        //Pipeline with 128KB segments 
        //segsize = 1024  << 7;
        return smpi_coll_tuned_bcast_ompi_pipeline (buff, count, datatype, 
                                                     root, comm);
                                                     

    } else if (communicator_size < 13) {
        // Split Binary with 8KB segments 
        return smpi_coll_tuned_bcast_ompi_split_bintree(buff, count, datatype, 
                                                         root, comm);
       
    } else if (communicator_size < (a_p64 * message_size + b_p64)) {
        // Pipeline with 64KB segments 
        //segsize = 1024 << 6;
        return smpi_coll_tuned_bcast_ompi_pipeline (buff, count, datatype, 
                                                     root, comm);
                                                     

    } else if (communicator_size < (a_p16 * message_size + b_p16)) {
        //Pipeline with 16KB segments 
        //segsize = 1024 << 4;
        return smpi_coll_tuned_bcast_ompi_pipeline (buff, count, datatype, 
                                                     root, comm);
                                                     

    }
    /* Pipeline with 8KB segments */
    //segsize = 1024 << 3;
    return smpi_coll_tuned_bcast_flattree_pipeline (buff, count, datatype, 
                                                 root, comm
                                                 /*segsize*/);
#if 0
    /* this is based on gige measurements */

    if (communicator_size  < 4) {
        return smpi_coll_tuned_bcast_intra_basic_linear (buff, count, datatype, root, comm, module);
    }
    if (communicator_size == 4) {
        if (message_size < 524288) segsize = 0;
        else segsize = 16384;
        return smpi_coll_tuned_bcast_intra_bintree (buff, count, datatype, root, comm, module, segsize);
    }
    if (communicator_size <= 8 && message_size < 4096) {
        return smpi_coll_tuned_bcast_intra_basic_linear (buff, count, datatype, root, comm, module);
    }
    if (communicator_size > 8 && message_size >= 32768 && message_size < 524288) {
        segsize = 16384;
        return  smpi_coll_tuned_bcast_intra_bintree (buff, count, datatype, root, comm, module, segsize);
    }
    if (message_size >= 524288) {
        segsize = 16384;
        return smpi_coll_tuned_bcast_intra_pipeline (buff, count, datatype, root, comm, module, segsize);
    }
    segsize = 0;
    /* once tested can swap this back in */
    /* return smpi_coll_tuned_bcast_intra_bmtree (buff, count, datatype, root, comm, segsize); */
    return smpi_coll_tuned_bcast_intra_bintree (buff, count, datatype, root, comm, module, segsize);
#endif  /* 0 */
}

int smpi_coll_tuned_reduce_ompi( void *sendbuf, void *recvbuf,
                                            int count, MPI_Datatype  datatype,
                                            MPI_Op   op, int root,
                                            MPI_Comm   comm
                                            )
{
    int communicator_size=0;
    //int segsize = 0;
    size_t message_size, dsize;
    const double a1 =  0.6016 / 1024.0; /* [1/B] */
    const double b1 =  1.3496;
    const double a2 =  0.0410 / 1024.0; /* [1/B] */
    const double b2 =  9.7128;
    const double a3 =  0.0422 / 1024.0; /* [1/B] */
    const double b3 =  1.1614;
    //const double a4 =  0.0033 / 1024.0; /* [1/B] */
    //const double b4 =  1.6761;

    //const int max_requests = 0; /* no limit on # of outstanding requests */

    communicator_size = smpi_comm_size(comm);

    /* need data size for decision function */
    dsize=smpi_datatype_size(datatype);
    message_size = dsize * count;   /* needed for decision */

    /**
     * If the operation is non commutative we currently have choice of linear 
     * or in-order binary tree algorithm.
     */
    if( !smpi_op_is_commute(op) ) {
        if ((communicator_size < 12) && (message_size < 2048)) {
            return smpi_coll_tuned_reduce_ompi_basic_linear (sendbuf, recvbuf, count, datatype, op, root, comm/*, module*/); 
        } 
        return smpi_coll_tuned_reduce_ompi_in_order_binary (sendbuf, recvbuf, count, datatype, op, root, comm/*, module,
                                                             0, max_requests*/); 
    }

    if ((communicator_size < 8) && (message_size < 512)){
        /* Linear_0K */
        return smpi_coll_tuned_reduce_ompi_basic_linear (sendbuf, recvbuf, count, datatype, op, root, comm); 
    } else if (((communicator_size < 8) && (message_size < 20480)) ||
               (message_size < 2048) || (count <= 1)) {
        /* Binomial_0K */
        //segsize = 0;
        return smpi_coll_tuned_reduce_ompi_binomial(sendbuf, recvbuf, count, datatype, op, root, comm/*, module,
                                                     segsize, max_requests*/);
    } else if (communicator_size > (a1 * message_size + b1)) {
        // Binomial_1K 
        //segsize = 1024;
        return smpi_coll_tuned_reduce_ompi_binomial(sendbuf, recvbuf, count, datatype, op, root, comm/*, module,
                                                     segsize, max_requests*/);
    } else if (communicator_size > (a2 * message_size + b2)) {
        // Pipeline_1K 
        //segsize = 1024;
        return smpi_coll_tuned_reduce_ompi_pipeline (sendbuf, recvbuf, count, datatype, op, root, comm/*, module, 
                                                      segsize, max_requests*/);
    } else if (communicator_size > (a3 * message_size + b3)) {
        // Binary_32K 
        //segsize = 32*1024;
        return smpi_coll_tuned_reduce_ompi_binary( sendbuf, recvbuf, count, datatype, op, root,
                                                    comm/*, module, segsize, max_requests*/);
    }
    /*if (communicator_size > (a4 * message_size + b4)) {
        // Pipeline_32K 
        segsize = 32*1024;
    } else {
        // Pipeline_64K 
        segsize = 64*1024;
    }*/
    return smpi_coll_tuned_reduce_ompi_pipeline (sendbuf, recvbuf, count, datatype, op, root, comm/*, module, 
                                                  segsize, max_requests*/);

#if 0
    /* for small messages use linear algorithm */
    if (message_size <= 4096) {
        segsize = 0;
        fanout = communicator_size - 1;
        /* when linear implemented or taken from basic put here, right now using chain as a linear system */
        /* it is implemented and I shouldn't be calling a chain with a fanout bigger than MAXTREEFANOUT from topo.h! */
        return smpi_coll_tuned_reduce_intra_basic_linear (sendbuf, recvbuf, count, datatype, op, root, comm, module); 
        /*        return smpi_coll_tuned_reduce_intra_chain (sendbuf, recvbuf, count, datatype, op, root, comm, segsize, fanout); */
    }
    if (message_size < 524288) {
        if (message_size <= 65536 ) {
            segsize = 32768;
            fanout = 8;
        } else {
            segsize = 1024;
            fanout = communicator_size/2;
        }
        /* later swap this for a binary tree */
        /*         fanout = 2; */
        return smpi_coll_tuned_reduce_intra_chain (sendbuf, recvbuf, count, datatype, op, root, comm, module,
                                                   segsize, fanout, max_requests);
    }
    segsize = 1024;
    return smpi_coll_tuned_reduce_intra_pipeline (sendbuf, recvbuf, count, datatype, op, root, comm, module,
                                                  segsize, max_requests);
#endif  /* 0 */
}

int smpi_coll_tuned_reduce_scatter_ompi( void *sbuf, void *rbuf,
                                                    int *rcounts,
                                                    MPI_Datatype dtype,
                                                    MPI_Op  op,
                                                    MPI_Comm  comm
                                                    )
{
    int comm_size, i, pow2;
    size_t total_message_size, dsize;
    const double a = 0.0012;
    const double b = 8.0;
    const size_t small_message_size = 12 * 1024;
    const size_t large_message_size = 256 * 1024;
    int zerocounts = 0;

    XBT_DEBUG("smpi_coll_tuned_reduce_scatter_ompi");
    
    comm_size = smpi_comm_size(comm);
    // We need data size for decision function 
    dsize=smpi_datatype_size(dtype);
    total_message_size = 0;
    for (i = 0; i < comm_size; i++) { 
        total_message_size += rcounts[i];
        if (0 == rcounts[i]) {
            zerocounts = 1;
        }
    }

    if( !smpi_op_is_commute(op) || (zerocounts)) {
        smpi_mpi_reduce_scatter (sbuf, rbuf, rcounts, 
                                                                    dtype, op, 
                                                                    comm); 
        return MPI_SUCCESS;
    }
   
    total_message_size *= dsize;

    // compute the nearest power of 2 
    for (pow2 = 1; pow2 < comm_size; pow2 <<= 1);

    if ((total_message_size <= small_message_size) ||
        ((total_message_size <= large_message_size) && (pow2 == comm_size)) ||
        (comm_size >= a * total_message_size + b)) {
        return 
            smpi_coll_tuned_reduce_scatter_ompi_basic_recursivehalving(sbuf, rbuf, rcounts,
                                                                        dtype, op,
                                                                        comm);
    } 
    return smpi_coll_tuned_reduce_scatter_ompi_ring(sbuf, rbuf, rcounts,
                                                     dtype, op,
                                                     comm);



}

int smpi_coll_tuned_allgather_ompi(void *sbuf, int scount, 
                                              MPI_Datatype sdtype,
                                              void* rbuf, int rcount, 
                                              MPI_Datatype rdtype, 
                                              MPI_Comm  comm
                                              )
{
    int communicator_size, pow2_size;
    size_t dsize, total_dsize;

    communicator_size = smpi_comm_size(comm);

    /* Special case for 2 processes */
    if (communicator_size == 2) {
        return smpi_coll_tuned_allgather_pair (sbuf, scount, sdtype, 
                                                          rbuf, rcount, rdtype, 
                                                          comm/*, module*/);
    }

    /* Determine complete data size */
    dsize=smpi_datatype_size(sdtype);
    total_dsize = dsize * scount * communicator_size;   
   
    for (pow2_size  = 1; pow2_size < communicator_size; pow2_size <<=1); 

    /* Decision based on MX 2Gb results from Grig cluster at 
       The University of Tennesse, Knoxville 
       - if total message size is less than 50KB use either bruck or 
       recursive doubling for non-power of two and power of two nodes, 
       respectively.
       - else use ring and neighbor exchange algorithms for odd and even 
       number of nodes, respectively.
    */
    if (total_dsize < 50000) {
        if (pow2_size == communicator_size) {
            return smpi_coll_tuned_allgather_rdb(sbuf, scount, sdtype, 
                                                                     rbuf, rcount, rdtype,
                                                                     comm);
        } else {
            return smpi_coll_tuned_allgather_bruck(sbuf, scount, sdtype, 
                                                         rbuf, rcount, rdtype, 
                                                         comm);
        }
    } else {
        if (communicator_size % 2) {
            return smpi_coll_tuned_allgather_ring(sbuf, scount, sdtype, 
                                                        rbuf, rcount, rdtype, 
                                                        comm);
        } else {
            return  smpi_coll_tuned_allgather_ompi_neighborexchange(sbuf, scount, sdtype,
                                                                     rbuf, rcount, rdtype,
                                                                     comm);
        }
    }
   
#if defined(USE_MPICH2_DECISION)
    /* Decision as in MPICH-2 
       presented in Thakur et.al. "Optimization of Collective Communication 
       Operations in MPICH", International Journal of High Performance Computing 
       Applications, Vol. 19, No. 1, 49-66 (2005)
       - for power-of-two processes and small and medium size messages 
       (up to 512KB) use recursive doubling
       - for non-power-of-two processes and small messages (80KB) use bruck,
       - for everything else use ring.
    */
    if ((pow2_size == communicator_size) && (total_dsize < 524288)) {
        return smpi_coll_tuned_allgather_rdb(sbuf, scount, sdtype, 
                                                                 rbuf, rcount, rdtype, 
                                                                 comm);
    } else if (total_dsize <= 81920) { 
        return smpi_coll_tuned_allgather_bruck(sbuf, scount, sdtype, 
                                                     rbuf, rcount, rdtype,
                                                     comm);
    } 
    return smpi_coll_tuned_allgather_ring(sbuf, scount, sdtype, 
                                                rbuf, rcount, rdtype,
                                                comm);
#endif  /* defined(USE_MPICH2_DECISION) */
}

int smpi_coll_tuned_allgatherv_ompi(void *sbuf, int scount, 
                                               MPI_Datatype sdtype,
                                               void* rbuf, int *rcounts, 
                                               int *rdispls,
                                               MPI_Datatype rdtype, 
                                               MPI_Comm  comm
                                               )
{
    int i;
    int communicator_size;
    size_t dsize, total_dsize;
    
    communicator_size = smpi_comm_size(comm);
    
    /* Special case for 2 processes */
    if (communicator_size == 2) {
        return smpi_coll_tuned_allgatherv_pair(sbuf, scount, sdtype,
                                                           rbuf, rcounts, rdispls, rdtype, 
                                                           comm);
    }
    
    /* Determine complete data size */
    dsize=smpi_datatype_size(sdtype);
    total_dsize = 0;
    for (i = 0; i < communicator_size; i++) {
        total_dsize += dsize * rcounts[i];
    }
    
    /* Decision based on allgather decision.   */
    if (total_dsize < 50000) {
/*        return smpi_coll_tuned_allgatherv_intra_bruck(sbuf, scount, sdtype, 
                                                      rbuf, rcounts, rdispls, rdtype, 
                                                      comm, module);*/
    return smpi_coll_tuned_allgatherv_ring(sbuf, scount, sdtype, 
                                                      rbuf, rcounts, rdispls, rdtype, 
                                                      comm);

    } else {
        if (communicator_size % 2) {
            return smpi_coll_tuned_allgatherv_ring(sbuf, scount, sdtype, 
                                                         rbuf, rcounts, rdispls, rdtype, 
                                                         comm);
        } else {
            return  smpi_coll_tuned_allgatherv_ompi_neighborexchange(sbuf, scount, sdtype,
                                                                      rbuf, rcounts, rdispls, rdtype, 
                                                                      comm);
        }
    }
}

int smpi_coll_tuned_gather_ompi(void *sbuf, int scount, 
                                           MPI_Datatype sdtype,
                                           void* rbuf, int rcount, 
                                           MPI_Datatype rdtype, 
                                           int root,
                                           MPI_Comm  comm
                                           )
{
    //const int large_segment_size = 32768;
    //const int small_segment_size = 1024;

    //const size_t large_block_size = 92160;
    const size_t intermediate_block_size = 6000;
    const size_t small_block_size = 1024;

    const int large_communicator_size = 60;
    const int small_communicator_size = 10;

    int communicator_size, rank;
    size_t dsize, block_size;

    XBT_DEBUG("smpi_coll_tuned_gather_ompi");

    communicator_size = smpi_comm_size(comm);
    rank = smpi_comm_rank(comm);

    // Determine block size 
    if (rank == root) {
        dsize = smpi_datatype_size(rdtype);
        block_size = dsize * rcount;
    } else {
        dsize = smpi_datatype_size(sdtype);
        block_size = dsize * scount;
    }

/*    if (block_size > large_block_size) {*/
/*        return smpi_coll_tuned_gather_ompi_linear_sync (sbuf, scount, sdtype, */
/*                                                         rbuf, rcount, rdtype, */
/*                                                         root, comm);*/

/*    } else*/ if (block_size > intermediate_block_size) {
        return smpi_coll_tuned_gather_ompi_linear_sync (sbuf, scount, sdtype, 
                                                         rbuf, rcount, rdtype, 
                                                         root, comm);

    } else if ((communicator_size > large_communicator_size) ||
               ((communicator_size > small_communicator_size) &&
                (block_size < small_block_size))) {
        return smpi_coll_tuned_gather_ompi_binomial (sbuf, scount, sdtype, 
                                                      rbuf, rcount, rdtype, 
                                                      root, comm);

    }
    // Otherwise, use basic linear 
    return smpi_coll_tuned_gather_ompi_basic_linear (sbuf, scount, sdtype, 
                                                      rbuf, rcount, rdtype, 
                                                      root, comm);
}

int smpi_coll_tuned_scatter_ompi(void *sbuf, int scount, 
                                            MPI_Datatype sdtype,
                                            void* rbuf, int rcount, 
                                            MPI_Datatype rdtype, 
                                            int root, MPI_Comm  comm
                                            )
{
    const size_t small_block_size = 300;
    const int small_comm_size = 10;
    int communicator_size, rank;
    size_t dsize, block_size;

    XBT_DEBUG("smpi_coll_tuned_scatter_ompi");

    communicator_size = smpi_comm_size(comm);
    rank = smpi_comm_rank(comm);
    // Determine block size 
    if (root == rank) {
        dsize=smpi_datatype_size(sdtype);
        block_size = dsize * scount;
    } else {
        dsize=smpi_datatype_size(rdtype);
        block_size = dsize * rcount;
    } 

    if ((communicator_size > small_comm_size) &&
        (block_size < small_block_size)) {
        if(rank!=root){
            sbuf=xbt_malloc(rcount*smpi_datatype_get_extent(rdtype));
            scount=rcount;
            sdtype=rdtype;
        }
        int ret=smpi_coll_tuned_scatter_ompi_binomial (sbuf, scount, sdtype,
            rbuf, rcount, rdtype,
            root, comm);
        if(rank!=root){
            xbt_free(sbuf);
        }
        return ret;
    }
    return smpi_coll_tuned_scatter_ompi_basic_linear (sbuf, scount, sdtype, 
                                                       rbuf, rcount, rdtype, 
                                                       root, comm);
}

