/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil -*- */ /* * Copyright (c) 2004-2005 The Trustees of Indiana University and Indiana * University Research and Technology * Corporation. All rights reserved. * Copyright (c) 2004-2015 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 (c) 2009 University of Houston. All rights reserved. * Copyright (c) 2013 Los Alamos National Security, LLC. All Rights * reserved. * $COPYRIGHT$ * * Additional copyrights may follow * * $HEADER$ */ #include "ompi_config.h" #include "mpi.h" #include "opal/util/bit_ops.h" #include "ompi/constants.h" #include "ompi/datatype/ompi_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 "ompi/mca/coll/base/coll_base_functions.h" #include "coll_base_topo.h" #include "coll_base_util.h" /* * ompi_coll_base_allreduce_intra_nonoverlapping * * This function just calls a reduce followed by a broadcast * both called functions are base but they complete sequentially, * i.e. no additional overlapping * meaning if the number of segments used is greater than the topo depth * then once the first segment of data is fully 'reduced' it is not broadcast * while the reduce continues (cost = cost-reduce + cost-bcast + decision x 3) * */ int ompi_coll_base_allreduce_intra_nonoverlapping(void *sbuf, void *rbuf, int count, struct ompi_datatype_t *dtype, struct ompi_op_t *op, struct ompi_communicator_t *comm, mca_coll_base_module_t *module) { int err, rank; rank = ompi_comm_rank(comm); OPAL_OUTPUT((ompi_coll_base_framework.framework_output,"coll:base:allreduce_intra_nonoverlapping rank %d", rank)); /* Reduce to 0 and broadcast. */ if (MPI_IN_PLACE == sbuf) { if (0 == rank) { err = comm->c_coll.coll_reduce (MPI_IN_PLACE, rbuf, count, dtype, op, 0, comm, comm->c_coll.coll_reduce_module); } else { err = comm->c_coll.coll_reduce (rbuf, NULL, count, dtype, op, 0, comm, comm->c_coll.coll_reduce_module); } } else { err = comm->c_coll.coll_reduce (sbuf, rbuf, count, dtype, op, 0, comm, comm->c_coll.coll_reduce_module); } if (MPI_SUCCESS != err) { return err; } return comm->c_coll.coll_bcast (rbuf, count, dtype, 0, comm, comm->c_coll.coll_bcast_module); } /* * ompi_coll_base_allreduce_intra_recursivedoubling * * Function: Recursive doubling algorithm for allreduce operation * Accepts: Same as MPI_Allreduce() * Returns: MPI_SUCCESS or error code * * Description: Implements recursive doubling algorithm for allreduce. * Original (non-segmented) implementation is used in MPICH-2 * for small and intermediate size messages. * The algorithm preserves order of operations so it can * be used both by commutative and non-commutative operations. * * Example on 7 nodes: * Initial state * # 0 1 2 3 4 5 6 * [0] [1] [2] [3] [4] [5] [6] * Initial adjustment step for non-power of two nodes. * old rank 1 3 5 6 * new rank 0 1 2 3 * [0+1] [2+3] [4+5] [6] * Step 1 * old rank 1 3 5 6 * new rank 0 1 2 3 * [0+1+] [0+1+] [4+5+] [4+5+] * [2+3+] [2+3+] [6 ] [6 ] * Step 2 * old rank 1 3 5 6 * new rank 0 1 2 3 * [0+1+] [0+1+] [0+1+] [0+1+] * [2+3+] [2+3+] [2+3+] [2+3+] * [4+5+] [4+5+] [4+5+] [4+5+] * [6 ] [6 ] [6 ] [6 ] * Final adjustment step for non-power of two nodes * # 0 1 2 3 4 5 6 * [0+1+] [0+1+] [0+1+] [0+1+] [0+1+] [0+1+] [0+1+] * [2+3+] [2+3+] [2+3+] [2+3+] [2+3+] [2+3+] [2+3+] * [4+5+] [4+5+] [4+5+] [4+5+] [4+5+] [4+5+] [4+5+] * [6 ] [6 ] [6 ] [6 ] [6 ] [6 ] [6 ] * */ int ompi_coll_base_allreduce_intra_recursivedoubling(void *sbuf, void *rbuf, int count, struct ompi_datatype_t *dtype, struct ompi_op_t *op, struct ompi_communicator_t *comm, mca_coll_base_module_t *module) { int ret, line, rank, size, adjsize, remote, distance; int newrank, newremote, extra_ranks; char *tmpsend = NULL, *tmprecv = NULL, *tmpswap = NULL, *inplacebuf = NULL; ptrdiff_t true_lb, true_extent, lb, extent; ompi_request_t *reqs[2] = {NULL, NULL}; size = ompi_comm_size(comm); rank = ompi_comm_rank(comm); OPAL_OUTPUT((ompi_coll_base_framework.framework_output, "coll:base:allreduce_intra_recursivedoubling rank %d", rank)); /* Special case for size == 1 */ if (1 == size) { if (MPI_IN_PLACE != sbuf) { ret = ompi_datatype_copy_content_same_ddt(dtype, count, (char*)rbuf, (char*)sbuf); if (ret < 0) { line = __LINE__; goto error_hndl; } } return MPI_SUCCESS; } /* Allocate and initialize temporary send buffer */ ret = ompi_datatype_get_extent(dtype, &lb, &extent); if (MPI_SUCCESS != ret) { line = __LINE__; goto error_hndl; } ret = ompi_datatype_get_true_extent(dtype, &true_lb, &true_extent); if (MPI_SUCCESS != ret) { line = __LINE__; goto error_hndl; } inplacebuf = (char*) malloc(true_extent + (ptrdiff_t)(count - 1) * extent); if (NULL == inplacebuf) { ret = -1; line = __LINE__; goto error_hndl; } if (MPI_IN_PLACE == sbuf) { ret = ompi_datatype_copy_content_same_ddt(dtype, count, inplacebuf, (char*)rbuf); if (ret < 0) { line = __LINE__; goto error_hndl; } } else { ret = ompi_datatype_copy_content_same_ddt(dtype, count, inplacebuf, (char*)sbuf); if (ret < 0) { line = __LINE__; goto error_hndl; } } tmpsend = (char*) inplacebuf; tmprecv = (char*) rbuf; /* Determine nearest power of two less than or equal to size */ adjsize = opal_next_poweroftwo (size); adjsize >>= 1; /* Handle non-power-of-two case: - Even ranks less than 2 * extra_ranks send their data to (rank + 1), and sets new rank to -1. - Odd ranks less than 2 * extra_ranks receive data from (rank - 1), apply appropriate operation, and set new rank to rank/2 - Everyone else sets rank to rank - extra_ranks */ extra_ranks = size - adjsize; if (rank < (2 * extra_ranks)) { if (0 == (rank % 2)) { ret = MCA_PML_CALL(send(tmpsend, count, dtype, (rank + 1), MCA_COLL_BASE_TAG_ALLREDUCE, MCA_PML_BASE_SEND_STANDARD, comm)); if (MPI_SUCCESS != ret) { line = __LINE__; goto error_hndl; } newrank = -1; } else { ret = MCA_PML_CALL(recv(tmprecv, count, dtype, (rank - 1), MCA_COLL_BASE_TAG_ALLREDUCE, comm, MPI_STATUS_IGNORE)); if (MPI_SUCCESS != ret) { line = __LINE__; goto error_hndl; } /* tmpsend = tmprecv (op) tmpsend */ ompi_op_reduce(op, tmprecv, tmpsend, count, dtype); newrank = rank >> 1; } } else { newrank = rank - extra_ranks; } /* Communication/Computation loop - Exchange message with remote node. - Perform appropriate operation taking in account order of operations: result = value (op) result */ for (distance = 0x1; distance < adjsize; distance <<=1) { if (newrank < 0) break; /* Determine remote node */ newremote = newrank ^ distance; remote = (newremote < extra_ranks)? (newremote * 2 + 1):(newremote + extra_ranks); /* Exchange the data */ ret = MCA_PML_CALL(irecv(tmprecv, count, dtype, remote, MCA_COLL_BASE_TAG_ALLREDUCE, comm, &reqs[0])); if (MPI_SUCCESS != ret) { line = __LINE__; goto error_hndl; } ret = MCA_PML_CALL(isend(tmpsend, count, dtype, remote, MCA_COLL_BASE_TAG_ALLREDUCE, MCA_PML_BASE_SEND_STANDARD, comm, &reqs[1])); if (MPI_SUCCESS != ret) { line = __LINE__; goto error_hndl; } ret = ompi_request_wait_all(2, reqs, MPI_STATUSES_IGNORE); if (MPI_SUCCESS != ret) { line = __LINE__; goto error_hndl; } /* Apply operation */ if (rank < remote) { /* tmprecv = tmpsend (op) tmprecv */ ompi_op_reduce(op, tmpsend, tmprecv, count, dtype); tmpswap = tmprecv; tmprecv = tmpsend; tmpsend = tmpswap; } else { /* tmpsend = tmprecv (op) tmpsend */ ompi_op_reduce(op, tmprecv, tmpsend, count, dtype); } } /* Handle non-power-of-two case: - Odd ranks less than 2 * extra_ranks send result from tmpsend to (rank - 1) - Even ranks less than 2 * extra_ranks receive result from (rank + 1) */ if (rank < (2 * extra_ranks)) { if (0 == (rank % 2)) { ret = MCA_PML_CALL(recv(rbuf, count, dtype, (rank + 1), MCA_COLL_BASE_TAG_ALLREDUCE, comm, MPI_STATUS_IGNORE)); if (MPI_SUCCESS != ret) { line = __LINE__; goto error_hndl; } tmpsend = (char*)rbuf; } else { ret = MCA_PML_CALL(send(tmpsend, count, dtype, (rank - 1), MCA_COLL_BASE_TAG_ALLREDUCE, MCA_PML_BASE_SEND_STANDARD, comm)); if (MPI_SUCCESS != ret) { line = __LINE__; goto error_hndl; } } } /* Ensure that the final result is in rbuf */ if (tmpsend != rbuf) { ret = ompi_datatype_copy_content_same_ddt(dtype, count, (char*)rbuf, tmpsend); if (ret < 0) { line = __LINE__; goto error_hndl; } } if (NULL != inplacebuf) free(inplacebuf); return MPI_SUCCESS; error_hndl: OPAL_OUTPUT((ompi_coll_base_framework.framework_output, "%s:%4d\tRank %d Error occurred %d\n", __FILE__, line, rank, ret)); if (NULL != inplacebuf) free(inplacebuf); return ret; } /* * ompi_coll_base_allreduce_intra_ring * * Function: Ring algorithm for allreduce operation * Accepts: Same as MPI_Allreduce() * Returns: MPI_SUCCESS or error code * * Description: Implements ring algorithm for allreduce: the message is * automatically segmented to segment of size M/N. * Algorithm requires 2*N - 1 steps. * * Limitations: The algorithm DOES NOT preserve order of operations so it * can be used only for commutative operations. * In addition, algorithm cannot work if the total count is * less than size. * Example on 5 nodes: * Initial state * # 0 1 2 3 4 * [00] [10] [20] [30] [40] * [01] [11] [21] [31] [41] * [02] [12] [22] [32] [42] * [03] [13] [23] [33] [43] * [04] [14] [24] [34] [44] * * COMPUTATION PHASE * Step 0: rank r sends block r to rank (r+1) and receives bloc (r-1) * from rank (r-1) [with wraparound]. * # 0 1 2 3 4 * [00] [00+10] [20] [30] [40] * [01] [11] [11+21] [31] [41] * [02] [12] [22] [22+32] [42] * [03] [13] [23] [33] [33+43] * [44+04] [14] [24] [34] [44] * * Step 1: rank r sends block (r-1) to rank (r+1) and receives bloc * (r-2) from rank (r-1) [with wraparound]. * # 0 1 2 3 4 * [00] [00+10] [01+10+20] [30] [40] * [01] [11] [11+21] [11+21+31] [41] * [02] [12] [22] [22+32] [22+32+42] * [33+43+03] [13] [23] [33] [33+43] * [44+04] [44+04+14] [24] [34] [44] * * Step 2: rank r sends block (r-2) to rank (r+1) and receives bloc * (r-2) from rank (r-1) [with wraparound]. * # 0 1 2 3 4 * [00] [00+10] [01+10+20] [01+10+20+30] [40] * [01] [11] [11+21] [11+21+31] [11+21+31+41] * [22+32+42+02] [12] [22] [22+32] [22+32+42] * [33+43+03] [33+43+03+13] [23] [33] [33+43] * [44+04] [44+04+14] [44+04+14+24] [34] [44] * * Step 3: rank r sends block (r-3) to rank (r+1) and receives bloc * (r-3) from rank (r-1) [with wraparound]. * # 0 1 2 3 4 * [00] [00+10] [01+10+20] [01+10+20+30] [FULL] * [FULL] [11] [11+21] [11+21+31] [11+21+31+41] * [22+32+42+02] [FULL] [22] [22+32] [22+32+42] * [33+43+03] [33+43+03+13] [FULL] [33] [33+43] * [44+04] [44+04+14] [44+04+14+24] [FULL] [44] * * DISTRIBUTION PHASE: ring ALLGATHER with ranks shifted by 1. * */ int ompi_coll_base_allreduce_intra_ring(void *sbuf, void *rbuf, int count, struct ompi_datatype_t *dtype, struct ompi_op_t *op, struct ompi_communicator_t *comm, mca_coll_base_module_t *module) { int ret, line, rank, size, k, recv_from, send_to, block_count, inbi; int early_segcount, late_segcount, split_rank, max_segcount; size_t typelng; char *tmpsend = NULL, *tmprecv = NULL, *inbuf[2] = {NULL, NULL}; ptrdiff_t true_lb, true_extent, lb, extent; ptrdiff_t block_offset, max_real_segsize; ompi_request_t *reqs[2] = {NULL, NULL}; size = ompi_comm_size(comm); rank = ompi_comm_rank(comm); OPAL_OUTPUT((ompi_coll_base_framework.framework_output, "coll:base:allreduce_intra_ring rank %d, count %d", rank, count)); /* Special case for size == 1 */ if (1 == size) { if (MPI_IN_PLACE != sbuf) { ret = ompi_datatype_copy_content_same_ddt(dtype, count, (char*)rbuf, (char*)sbuf); if (ret < 0) { line = __LINE__; goto error_hndl; } } return MPI_SUCCESS; } /* Special case for count less than size - use recursive doubling */ if (count < size) { OPAL_OUTPUT((ompi_coll_base_framework.framework_output, "coll:base:allreduce_ring rank %d/%d, count %d, switching to recursive doubling", rank, size, count)); return (ompi_coll_base_allreduce_intra_recursivedoubling(sbuf, rbuf, count, dtype, op, comm, module)); } /* Allocate and initialize temporary buffers */ ret = ompi_datatype_get_extent(dtype, &lb, &extent); if (MPI_SUCCESS != ret) { line = __LINE__; goto error_hndl; } ret = ompi_datatype_get_true_extent(dtype, &true_lb, &true_extent); if (MPI_SUCCESS != ret) { line = __LINE__; goto error_hndl; } ret = ompi_datatype_type_size( dtype, &typelng); if (MPI_SUCCESS != ret) { line = __LINE__; goto error_hndl; } /* Determine the number of elements per block and corresponding block sizes. The blocks are divided into "early" and "late" ones: blocks 0 .. (split_rank - 1) are "early" and blocks (split_rank) .. (size - 1) are "late". Early blocks are at most 1 element larger than the late ones. */ COLL_BASE_COMPUTE_BLOCKCOUNT( count, size, split_rank, early_segcount, late_segcount ); max_segcount = early_segcount; max_real_segsize = true_extent + (max_segcount - 1) * extent; inbuf[0] = (char*)malloc(max_real_segsize); if (NULL == inbuf[0]) { ret = -1; line = __LINE__; goto error_hndl; } if (size > 2) { inbuf[1] = (char*)malloc(max_real_segsize); if (NULL == inbuf[1]) { ret = -1; line = __LINE__; goto error_hndl; } } /* Handle MPI_IN_PLACE */ if (MPI_IN_PLACE != sbuf) { ret = ompi_datatype_copy_content_same_ddt(dtype, count, (char*)rbuf, (char*)sbuf); if (ret < 0) { line = __LINE__; goto error_hndl; } } /* Computation loop */ /* For each of the remote nodes: - post irecv for block (r-1) - send block (r) - in loop for every step k = 2 .. n - post irecv for block (r + n - k) % n - wait on block (r + n - k + 1) % n to arrive - compute on block (r + n - k + 1) % n - send block (r + n - k + 1) % n - wait on block (r + 1) - compute on block (r + 1) - send block (r + 1) to rank (r + 1) Note that we must be careful when computing the begining of buffers and for send operations and computation we must compute the exact block size. */ send_to = (rank + 1) % size; recv_from = (rank + size - 1) % size; inbi = 0; /* Initialize first receive from the neighbor on the left */ ret = MCA_PML_CALL(irecv(inbuf[inbi], max_segcount, dtype, recv_from, MCA_COLL_BASE_TAG_ALLREDUCE, comm, &reqs[inbi])); if (MPI_SUCCESS != ret) { line = __LINE__; goto error_hndl; } /* Send first block (my block) to the neighbor on the right */ block_offset = ((rank < split_rank)? ((ptrdiff_t)rank * (ptrdiff_t)early_segcount) : ((ptrdiff_t)rank * (ptrdiff_t)late_segcount + split_rank)); block_count = ((rank < split_rank)? early_segcount : late_segcount); tmpsend = ((char*)rbuf) + block_offset * extent; ret = MCA_PML_CALL(send(tmpsend, block_count, dtype, send_to, MCA_COLL_BASE_TAG_ALLREDUCE, MCA_PML_BASE_SEND_STANDARD, comm)); if (MPI_SUCCESS != ret) { line = __LINE__; goto error_hndl; } for (k = 2; k < size; k++) { const int prevblock = (rank + size - k + 1) % size; inbi = inbi ^ 0x1; /* Post irecv for the current block */ ret = MCA_PML_CALL(irecv(inbuf[inbi], max_segcount, dtype, recv_from, MCA_COLL_BASE_TAG_ALLREDUCE, comm, &reqs[inbi])); if (MPI_SUCCESS != ret) { line = __LINE__; goto error_hndl; } /* Wait on previous block to arrive */ ret = ompi_request_wait(&reqs[inbi ^ 0x1], MPI_STATUS_IGNORE); if (MPI_SUCCESS != ret) { line = __LINE__; goto error_hndl; } /* Apply operation on previous block: result goes to rbuf rbuf[prevblock] = inbuf[inbi ^ 0x1] (op) rbuf[prevblock] */ block_offset = ((prevblock < split_rank)? ((ptrdiff_t)prevblock * early_segcount) : ((ptrdiff_t)prevblock * late_segcount + split_rank)); block_count = ((prevblock < split_rank)? early_segcount : late_segcount); tmprecv = ((char*)rbuf) + (ptrdiff_t)block_offset * extent; ompi_op_reduce(op, inbuf[inbi ^ 0x1], tmprecv, block_count, dtype); /* send previous block to send_to */ ret = MCA_PML_CALL(send(tmprecv, block_count, dtype, send_to, MCA_COLL_BASE_TAG_ALLREDUCE, MCA_PML_BASE_SEND_STANDARD, comm)); if (MPI_SUCCESS != ret) { line = __LINE__; goto error_hndl; } } /* Wait on the last block to arrive */ ret = ompi_request_wait(&reqs[inbi], MPI_STATUS_IGNORE); if (MPI_SUCCESS != ret) { line = __LINE__; goto error_hndl; } /* Apply operation on the last block (from neighbor (rank + 1) rbuf[rank+1] = inbuf[inbi] (op) rbuf[rank + 1] */ recv_from = (rank + 1) % size; block_offset = ((recv_from < split_rank)? ((ptrdiff_t)recv_from * early_segcount) : ((ptrdiff_t)recv_from * late_segcount + split_rank)); block_count = ((recv_from < split_rank)? early_segcount : late_segcount); tmprecv = ((char*)rbuf) + (ptrdiff_t)block_offset * extent; ompi_op_reduce(op, inbuf[inbi], tmprecv, block_count, dtype); /* Distribution loop - variation of ring allgather */ send_to = (rank + 1) % size; recv_from = (rank + size - 1) % size; for (k = 0; k < size - 1; k++) { const int recv_data_from = (rank + size - k) % size; const int send_data_from = (rank + 1 + size - k) % size; const int send_block_offset = ((send_data_from < split_rank)? ((ptrdiff_t)send_data_from * early_segcount) : ((ptrdiff_t)send_data_from * late_segcount + split_rank)); const int recv_block_offset = ((recv_data_from < split_rank)? ((ptrdiff_t)recv_data_from * early_segcount) : ((ptrdiff_t)recv_data_from * late_segcount + split_rank)); block_count = ((send_data_from < split_rank)? early_segcount : late_segcount); tmprecv = (char*)rbuf + (ptrdiff_t)recv_block_offset * extent; tmpsend = (char*)rbuf + (ptrdiff_t)send_block_offset * extent; ret = ompi_coll_base_sendrecv(tmpsend, block_count, dtype, send_to, MCA_COLL_BASE_TAG_ALLREDUCE, tmprecv, max_segcount, dtype, recv_from, MCA_COLL_BASE_TAG_ALLREDUCE, comm, MPI_STATUS_IGNORE, rank); if (MPI_SUCCESS != ret) { line = __LINE__; goto error_hndl;} } if (NULL != inbuf[0]) free(inbuf[0]); if (NULL != inbuf[1]) free(inbuf[1]); return MPI_SUCCESS; error_hndl: OPAL_OUTPUT((ompi_coll_base_framework.framework_output, "%s:%4d\tRank %d Error occurred %d\n", __FILE__, line, rank, ret)); if (NULL != inbuf[0]) free(inbuf[0]); if (NULL != inbuf[1]) free(inbuf[1]); return ret; } /* * ompi_coll_base_allreduce_intra_ring_segmented * * Function: Pipelined ring algorithm for allreduce operation * Accepts: Same as MPI_Allreduce(), segment size * Returns: MPI_SUCCESS or error code * * Description: Implements pipelined ring algorithm for allreduce: * user supplies suggested segment size for the pipelining of * reduce operation. * The segment size determines the number of phases, np, for * the algorithm execution. * The message is automatically divided into blocks of * approximately (count / (np * segcount)) elements. * At the end of reduction phase, allgather like step is * executed. * Algorithm requires (np + 1)*(N - 1) steps. * * Limitations: The algorithm DOES NOT preserve order of operations so it * can be used only for commutative operations. * In addition, algorithm cannot work if the total size is * less than size * segment size. * Example on 3 nodes with 2 phases * Initial state * # 0 1 2 * [00a] [10a] [20a] * [00b] [10b] [20b] * [01a] [11a] [21a] * [01b] [11b] [21b] * [02a] [12a] [22a] * [02b] [12b] [22b] * * COMPUTATION PHASE 0 (a) * Step 0: rank r sends block ra to rank (r+1) and receives bloc (r-1)a * from rank (r-1) [with wraparound]. * # 0 1 2 * [00a] [00a+10a] [20a] * [00b] [10b] [20b] * [01a] [11a] [11a+21a] * [01b] [11b] [21b] * [22a+02a] [12a] [22a] * [02b] [12b] [22b] * * Step 1: rank r sends block (r-1)a to rank (r+1) and receives bloc * (r-2)a from rank (r-1) [with wraparound]. * # 0 1 2 * [00a] [00a+10a] [00a+10a+20a] * [00b] [10b] [20b] * [11a+21a+01a] [11a] [11a+21a] * [01b] [11b] [21b] * [22a+02a] [22a+02a+12a] [22a] * [02b] [12b] [22b] * * COMPUTATION PHASE 1 (b) * Step 0: rank r sends block rb to rank (r+1) and receives bloc (r-1)b * from rank (r-1) [with wraparound]. * # 0 1 2 * [00a] [00a+10a] [20a] * [00b] [00b+10b] [20b] * [01a] [11a] [11a+21a] * [01b] [11b] [11b+21b] * [22a+02a] [12a] [22a] * [22b+02b] [12b] [22b] * * Step 1: rank r sends block (r-1)b to rank (r+1) and receives bloc * (r-2)b from rank (r-1) [with wraparound]. * # 0 1 2 * [00a] [00a+10a] [00a+10a+20a] * [00b] [10b] [0bb+10b+20b] * [11a+21a+01a] [11a] [11a+21a] * [11b+21b+01b] [11b] [21b] * [22a+02a] [22a+02a+12a] [22a] * [02b] [22b+01b+12b] [22b] * * * DISTRIBUTION PHASE: ring ALLGATHER with ranks shifted by 1 (same as * in regular ring algorithm. * */ int ompi_coll_base_allreduce_intra_ring_segmented(void *sbuf, void *rbuf, int count, struct ompi_datatype_t *dtype, struct ompi_op_t *op, struct ompi_communicator_t *comm, mca_coll_base_module_t *module, uint32_t segsize) { int ret, line, rank, size, k, recv_from, send_to; int early_blockcount, late_blockcount, split_rank; int segcount, max_segcount, num_phases, phase, block_count, inbi; size_t typelng; char *tmpsend = NULL, *tmprecv = NULL, *inbuf[2] = {NULL, NULL}; ptrdiff_t true_lb, true_extent, lb, extent; ptrdiff_t block_offset, max_real_segsize; ompi_request_t *reqs[2] = {NULL, NULL}; size = ompi_comm_size(comm); rank = ompi_comm_rank(comm); OPAL_OUTPUT((ompi_coll_base_framework.framework_output, "coll:base:allreduce_intra_ring_segmented rank %d, count %d", rank, count)); /* Special case for size == 1 */ if (1 == size) { if (MPI_IN_PLACE != sbuf) { ret = ompi_datatype_copy_content_same_ddt(dtype, count, (char*)rbuf, (char*)sbuf); if (ret < 0) { line = __LINE__; goto error_hndl; } } return MPI_SUCCESS; } /* Determine segment count based on the suggested segment size */ ret = ompi_datatype_get_extent(dtype, &lb, &extent); if (MPI_SUCCESS != ret) { line = __LINE__; goto error_hndl; } ret = ompi_datatype_get_true_extent(dtype, &true_lb, &true_extent); if (MPI_SUCCESS != ret) { line = __LINE__; goto error_hndl; } ret = ompi_datatype_type_size( dtype, &typelng); if (MPI_SUCCESS != ret) { line = __LINE__; goto error_hndl; } segcount = count; COLL_BASE_COMPUTED_SEGCOUNT(segsize, typelng, segcount) /* Special case for count less than size * segcount - use regular ring */ if (count < (size * segcount)) { OPAL_OUTPUT((ompi_coll_base_framework.framework_output, "coll:base:allreduce_ring_segmented rank %d/%d, count %d, switching to regular ring", rank, size, count)); return (ompi_coll_base_allreduce_intra_ring(sbuf, rbuf, count, dtype, op, comm, module)); } /* Determine the number of phases of the algorithm */ num_phases = count / (size * segcount); if ((count % (size * segcount) >= size) && (count % (size * segcount) > ((size * segcount) / 2))) { num_phases++; } /* Determine the number of elements per block and corresponding block sizes. The blocks are divided into "early" and "late" ones: blocks 0 .. (split_rank - 1) are "early" and blocks (split_rank) .. (size - 1) are "late". Early blocks are at most 1 element larger than the late ones. Note, these blocks will be split into num_phases segments, out of the largest one will have max_segcount elements. */ COLL_BASE_COMPUTE_BLOCKCOUNT( count, size, split_rank, early_blockcount, late_blockcount ); COLL_BASE_COMPUTE_BLOCKCOUNT( early_blockcount, num_phases, inbi, max_segcount, k); max_real_segsize = true_extent + (ptrdiff_t)(max_segcount - 1) * extent; /* Allocate and initialize temporary buffers */ inbuf[0] = (char*)malloc(max_real_segsize); if (NULL == inbuf[0]) { ret = -1; line = __LINE__; goto error_hndl; } if (size > 2) { inbuf[1] = (char*)malloc(max_real_segsize); if (NULL == inbuf[1]) { ret = -1; line = __LINE__; goto error_hndl; } } /* Handle MPI_IN_PLACE */ if (MPI_IN_PLACE != sbuf) { ret = ompi_datatype_copy_content_same_ddt(dtype, count, (char*)rbuf, (char*)sbuf); if (ret < 0) { line = __LINE__; goto error_hndl; } } /* Computation loop: for each phase, repeat ring allreduce computation loop */ for (phase = 0; phase < num_phases; phase ++) { ptrdiff_t phase_offset; int early_phase_segcount, late_phase_segcount, split_phase, phase_count; /* For each of the remote nodes: - post irecv for block (r-1) - send block (r) To do this, first compute block offset and count, and use block offset to compute phase offset. - in loop for every step k = 2 .. n - post irecv for block (r + n - k) % n - wait on block (r + n - k + 1) % n to arrive - compute on block (r + n - k + 1) % n - send block (r + n - k + 1) % n - wait on block (r + 1) - compute on block (r + 1) - send block (r + 1) to rank (r + 1) Note that we must be careful when computing the begining of buffers and for send operations and computation we must compute the exact block size. */ send_to = (rank + 1) % size; recv_from = (rank + size - 1) % size; inbi = 0; /* Initialize first receive from the neighbor on the left */ ret = MCA_PML_CALL(irecv(inbuf[inbi], max_segcount, dtype, recv_from, MCA_COLL_BASE_TAG_ALLREDUCE, comm, &reqs[inbi])); if (MPI_SUCCESS != ret) { line = __LINE__; goto error_hndl; } /* Send first block (my block) to the neighbor on the right: - compute my block and phase offset - send data */ block_offset = ((rank < split_rank)? ((ptrdiff_t)rank * (ptrdiff_t)early_blockcount) : ((ptrdiff_t)rank * (ptrdiff_t)late_blockcount + split_rank)); block_count = ((rank < split_rank)? early_blockcount : late_blockcount); COLL_BASE_COMPUTE_BLOCKCOUNT(block_count, num_phases, split_phase, early_phase_segcount, late_phase_segcount) phase_count = ((phase < split_phase)? (early_phase_segcount) : (late_phase_segcount)); phase_offset = ((phase < split_phase)? ((ptrdiff_t)phase * (ptrdiff_t)early_phase_segcount) : ((ptrdiff_t)phase * (ptrdiff_t)late_phase_segcount + split_phase)); tmpsend = ((char*)rbuf) + (ptrdiff_t)(block_offset + phase_offset) * extent; ret = MCA_PML_CALL(send(tmpsend, phase_count, dtype, send_to, MCA_COLL_BASE_TAG_ALLREDUCE, MCA_PML_BASE_SEND_STANDARD, comm)); if (MPI_SUCCESS != ret) { line = __LINE__; goto error_hndl; } for (k = 2; k < size; k++) { const int prevblock = (rank + size - k + 1) % size; inbi = inbi ^ 0x1; /* Post irecv for the current block */ ret = MCA_PML_CALL(irecv(inbuf[inbi], max_segcount, dtype, recv_from, MCA_COLL_BASE_TAG_ALLREDUCE, comm, &reqs[inbi])); if (MPI_SUCCESS != ret) { line = __LINE__; goto error_hndl; } /* Wait on previous block to arrive */ ret = ompi_request_wait(&reqs[inbi ^ 0x1], MPI_STATUS_IGNORE); if (MPI_SUCCESS != ret) { line = __LINE__; goto error_hndl; } /* Apply operation on previous block: result goes to rbuf rbuf[prevblock] = inbuf[inbi ^ 0x1] (op) rbuf[prevblock] */ block_offset = ((prevblock < split_rank)? ((ptrdiff_t)prevblock * (ptrdiff_t)early_blockcount) : ((ptrdiff_t)prevblock * (ptrdiff_t)late_blockcount + split_rank)); block_count = ((prevblock < split_rank)? early_blockcount : late_blockcount); COLL_BASE_COMPUTE_BLOCKCOUNT(block_count, num_phases, split_phase, early_phase_segcount, late_phase_segcount) phase_count = ((phase < split_phase)? (early_phase_segcount) : (late_phase_segcount)); phase_offset = ((phase < split_phase)? ((ptrdiff_t)phase * (ptrdiff_t)early_phase_segcount) : ((ptrdiff_t)phase * (ptrdiff_t)late_phase_segcount + split_phase)); tmprecv = ((char*)rbuf) + (ptrdiff_t)(block_offset + phase_offset) * extent; ompi_op_reduce(op, inbuf[inbi ^ 0x1], tmprecv, phase_count, dtype); /* send previous block to send_to */ ret = MCA_PML_CALL(send(tmprecv, phase_count, dtype, send_to, MCA_COLL_BASE_TAG_ALLREDUCE, MCA_PML_BASE_SEND_STANDARD, comm)); if (MPI_SUCCESS != ret) { line = __LINE__; goto error_hndl; } } /* Wait on the last block to arrive */ ret = ompi_request_wait(&reqs[inbi], MPI_STATUS_IGNORE); if (MPI_SUCCESS != ret) { line = __LINE__; goto error_hndl; } /* Apply operation on the last block (from neighbor (rank + 1) rbuf[rank+1] = inbuf[inbi] (op) rbuf[rank + 1] */ recv_from = (rank + 1) % size; block_offset = ((recv_from < split_rank)? ((ptrdiff_t)recv_from * (ptrdiff_t)early_blockcount) : ((ptrdiff_t)recv_from * (ptrdiff_t)late_blockcount + split_rank)); block_count = ((recv_from < split_rank)? early_blockcount : late_blockcount); COLL_BASE_COMPUTE_BLOCKCOUNT(block_count, num_phases, split_phase, early_phase_segcount, late_phase_segcount) phase_count = ((phase < split_phase)? (early_phase_segcount) : (late_phase_segcount)); phase_offset = ((phase < split_phase)? ((ptrdiff_t)phase * (ptrdiff_t)early_phase_segcount) : ((ptrdiff_t)phase * (ptrdiff_t)late_phase_segcount + split_phase)); tmprecv = ((char*)rbuf) + (ptrdiff_t)(block_offset + phase_offset) * extent; ompi_op_reduce(op, inbuf[inbi], tmprecv, phase_count, dtype); } /* Distribution loop - variation of ring allgather */ send_to = (rank + 1) % size; recv_from = (rank + size - 1) % size; for (k = 0; k < size - 1; k++) { const int recv_data_from = (rank + size - k) % size; const int send_data_from = (rank + 1 + size - k) % size; const int send_block_offset = ((send_data_from < split_rank)? ((ptrdiff_t)send_data_from * (ptrdiff_t)early_blockcount) : ((ptrdiff_t)send_data_from * (ptrdiff_t)late_blockcount + split_rank)); const int recv_block_offset = ((recv_data_from < split_rank)? ((ptrdiff_t)recv_data_from * (ptrdiff_t)early_blockcount) : ((ptrdiff_t)recv_data_from * (ptrdiff_t)late_blockcount + split_rank)); block_count = ((send_data_from < split_rank)? early_blockcount : late_blockcount); tmprecv = (char*)rbuf + (ptrdiff_t)recv_block_offset * extent; tmpsend = (char*)rbuf + (ptrdiff_t)send_block_offset * extent; ret = ompi_coll_base_sendrecv(tmpsend, block_count, dtype, send_to, MCA_COLL_BASE_TAG_ALLREDUCE, tmprecv, early_blockcount, dtype, recv_from, MCA_COLL_BASE_TAG_ALLREDUCE, comm, MPI_STATUS_IGNORE, rank); if (MPI_SUCCESS != ret) { line = __LINE__; goto error_hndl;} } if (NULL != inbuf[0]) free(inbuf[0]); if (NULL != inbuf[1]) free(inbuf[1]); return MPI_SUCCESS; error_hndl: OPAL_OUTPUT((ompi_coll_base_framework.framework_output, "%s:%4d\tRank %d Error occurred %d\n", __FILE__, line, rank, ret)); if (NULL != inbuf[0]) free(inbuf[0]); if (NULL != inbuf[1]) free(inbuf[1]); return ret; } /* * Linear functions are copied from the BASIC coll module * they do not segment the message and are simple implementations * but for some small number of nodes and/or small data sizes they * are just as fast as base/tree based segmenting operations * and as such may be selected by the decision functions * These are copied into this module due to the way we select modules * in V1. i.e. in V2 we will handle this differently and so will not * have to duplicate code. * GEF Oct05 after asking Jeff. */ /* copied function (with appropriate renaming) starts here */ /* * allreduce_intra * * Function: - allreduce using other MPI collectives * Accepts: - same as MPI_Allreduce() * Returns: - MPI_SUCCESS or error code */ int ompi_coll_base_allreduce_intra_basic_linear(void *sbuf, void *rbuf, int count, struct ompi_datatype_t *dtype, struct ompi_op_t *op, struct ompi_communicator_t *comm, mca_coll_base_module_t *module) { int err, rank; rank = ompi_comm_rank(comm); OPAL_OUTPUT((ompi_coll_base_framework.framework_output,"coll:base:allreduce_intra_basic_linear rank %d", rank)); /* Reduce to 0 and broadcast. */ if (MPI_IN_PLACE == sbuf) { if (0 == rank) { err = ompi_coll_base_reduce_intra_basic_linear (MPI_IN_PLACE, rbuf, count, dtype, op, 0, comm, module); } else { err = ompi_coll_base_reduce_intra_basic_linear(rbuf, NULL, count, dtype, op, 0, comm, module); } } else { err = ompi_coll_base_reduce_intra_basic_linear(sbuf, rbuf, count, dtype, op, 0, comm, module); } if (MPI_SUCCESS != err) { return err; } return ompi_coll_base_bcast_intra_basic_linear(rbuf, count, dtype, 0, comm, module); } /* copied function (with appropriate renaming) ends here */