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openmpi/ompi/mca/coll/sm/coll_sm_reduce.c
George Bosilca 4d00c59b2e Cleanup the memory handling for temporary buffers in
some of the collective modules. Added a new function
opan_datatype_span, to compute the memory span of
count number of datatype, excluding the gaps in the
beginning and at the end. If a memory allocation is
made using the returned value, the gap (also returned)
should be removed from the allocated pointer.
2015-12-02 20:42:18 -05:00

569 строки
22 KiB
C

/*
* 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) 2009-2013 Cisco Systems, Inc. All rights reserved.
* Copyright (c) 2015 Research Organization for Information Science
* and Technology (RIST). All rights reserved.
* $COPYRIGHT$
*
* Additional copyrights may follow
*
* $HEADER$
*/
#include "ompi_config.h"
#include <string.h>
#include "opal/datatype/opal_convertor.h"
#include "opal/sys/atomic.h"
#include "ompi/constants.h"
#include "ompi/communicator/communicator.h"
#include "ompi/mca/coll/coll.h"
#include "ompi/op/op.h"
#include "coll_sm.h"
/*
* Local functions
*/
static int reduce_inorder(const void *sbuf, void* rbuf, int count,
struct ompi_datatype_t *dtype,
struct ompi_op_t *op,
int root, struct ompi_communicator_t *comm,
mca_coll_base_module_t *module);
#define WANT_REDUCE_NO_ORDER 0
#if WANT_REDUCE_NO_ORDER
static int reduce_no_order(const void *sbuf, void* rbuf, int count,
struct ompi_datatype_t *dtype,
struct ompi_op_t *op,
int root, struct ompi_communicator_t *comm,
mca_coll_base_module_t *module);
#endif
/*
* Useful utility routine
*/
#if !defined(min)
static inline int min(int a, int b)
{
return (a < b) ? a : b;
}
#endif
/**
* Shared memory reduction.
*
* Simply farms out to the associative or non-associative functions.
*/
int mca_coll_sm_reduce_intra(const void *sbuf, void* rbuf, int count,
struct ompi_datatype_t *dtype,
struct ompi_op_t *op,
int root, struct ompi_communicator_t *comm,
mca_coll_base_module_t *module)
{
size_t size;
mca_coll_sm_module_t *sm_module = (mca_coll_sm_module_t*) module;
/* There are several possibilities:
*
* 0. If the datatype is larger than a segment, fall back to
* underlying module
* 1. If the op is user-defined, use the strict order
* 2. If the op is intrinsic:
* a. If the op is float-associative, use the unordered
* b. If the op is not float-associative:
* i. if the data is floating point, use the strict order
* ii. if the data is not floating point, use the unordered
*/
ompi_datatype_type_size(dtype, &size);
if ((int)size > mca_coll_sm_component.sm_control_size) {
return sm_module->previous_reduce(sbuf, rbuf, count,
dtype, op, root, comm,
sm_module->previous_reduce_module);
}
#if WANT_REDUCE_NO_ORDER
else {
/* Lazily enable the module the first time we invoke a
collective on it */
if (!sm_module->enabled) {
if (OMPI_SUCCESS !=
(ret = ompi_coll_sm_lazy_enable(module, comm))) {
return ret;
}
}
if (!ompi_op_is_intrinsic(op) ||
(ompi_op_is_intrinsic(op) && !ompi_op_is_float_assoc(op) &&
0 != (dtype->flags & OMPI_DATATYPE_FLAG_DATA_FLOAT))) {
return reduce_inorder(sbuf, rbuf, count, dtype, op,
root, comm, module);
} else {
return reduce_no_order(sbuf, rbuf, count, dtype, op,
root, comm, module);
}
}
#else
else {
/* Lazily enable the module the first time we invoke a
collective on it */
if (!sm_module->enabled) {
int ret;
if (OMPI_SUCCESS !=
(ret = ompi_coll_sm_lazy_enable(module, comm))) {
return ret;
}
}
return reduce_inorder(sbuf, rbuf, count, dtype, op, root, comm, module);
}
#endif
}
/**
* In-order shared memory reduction.
*
* This function performs the reduction in order -- combining elements
* starting with (0 operation 1), then (result operation 2), then
* (result operation 3), etc.
*
* Root's algorithm:
*
* If our datatype is "friendly" (i.e., the representation of the
* buffer is the same packed as it is unpacked), then the root doesn't
* need a temporary buffer -- we can combine the operands directly
* from the shared memory segments to the root's rbuf. Otherwise, we
* need a receive convertor and receive each fragment into a temporary
* buffer where we can combine that operan with the root's rbuf.
*
* In general, there are two loops:
*
* 1. loop over all fragments (which must be done in units of an
* integer number of datatypes -- remember that if this function is
* called, we know that the datattype is smaller than the max size of
* a fragment, so this is definitely possible)
*
* 2. loop over all the processes -- 0 to (comm_size-1).
* For process 0:
* - if the root==0, copy the *entire* buffer (i.e., don't copy
* fragment by fragment -- might as well copy the entire thing) the
* first time through the algorithm, and no-op every other time
* - else, copy from the shmem fragment to the out buffer
* For all other proceses:
* - if root==i, combine the relevant fragment from the sbuf to the
* relevant fragment on the rbuf
* - else, if the datatype is friendly, combine relevant fragment from
* the shmem segment to the relevant fragment in the rbuf. Otherwise,
* use the convertor to copy the fragment out of shmem into a temp
* buffer and do the combination from there to the rbuf.
*
* If we don't have a friendly datatype, then free the temporary
* buffer at the end.
*/
static int reduce_inorder(const void *sbuf, void* rbuf, int count,
struct ompi_datatype_t *dtype,
struct ompi_op_t *op,
int root, struct ompi_communicator_t *comm,
mca_coll_base_module_t *module)
{
struct iovec iov;
mca_coll_sm_module_t *sm_module = (mca_coll_sm_module_t*) module;
mca_coll_sm_comm_t *data = sm_module->sm_comm_data;
int ret, rank, size;
int flag_num, segment_num, max_segment_num;
size_t total_size, max_data, bytes;
mca_coll_sm_in_use_flag_t *flag;
mca_coll_sm_data_index_t *index;
size_t ddt_size, segsize;
size_t segment_ddt_count, segment_ddt_bytes, zero = 0;
ptrdiff_t extent, gap;
/* Setup some identities */
rank = ompi_comm_rank(comm);
size = ompi_comm_size(comm);
/* Figure out how much we should have the convertor copy. We need
to have it be in units of a datatype -- i.e., we only want to
copy a whole datatype worth of data or none at all (we've
already guaranteed above that the datatype is not larger than a
segment, so we'll at least get 1). */
/* ddt_size is the packed size (e.g., MPI_SHORT_INT is 6) */
ompi_datatype_type_size(dtype, &ddt_size);
/* extent is from lb to ub (e.g., MPI_SHORT_INT is 8) */
ompi_datatype_type_extent(dtype, &extent);
segment_ddt_count = mca_coll_sm_component.sm_fragment_size / ddt_size;
iov.iov_len = segment_ddt_bytes = segment_ddt_count * ddt_size;
total_size = ddt_size * count;
bytes = 0;
/* Only have one top-level decision as to whether I'm the root or
not. Do this at the slight expense of repeating a little logic
-- but it's better than a conditional branch in every loop
iteration. */
/*********************************************************************
* Root
*********************************************************************/
if (root == rank) {
opal_convertor_t rtb_convertor, rbuf_convertor;
char *reduce_temp_buffer, *free_buffer, *reduce_target;
char *inplace_temp;
int peer;
size_t count_left = (size_t)count;
int frag_num = 0;
bool first_operation = true;
/* If the datatype is the same packed as it is unpacked, we
can save a memory copy and just do the reduction operation
directly from the shared memory segment. However, if the
representation is not the same, then we need to get a
receive convertor and a temporary buffer to receive
into. */
if (ompi_datatype_is_contiguous_memory_layout(dtype, count)) {
reduce_temp_buffer = free_buffer = NULL;
} else {
/* When we have a non-contiguous datatype, we need one or
* two convertors:
*
* rtb_convertor: unpacking from the shmem to the
* reduce_temp_buffer (where we can then apply the
* reduction).
*
* rbuf_convertor: unpacking from the shmem directly to the
* rbuf (no need to go to the reduce_temp_buffer first and
* then apply the reduction -- just copy straight to the
* target buffer).
*/
OBJ_CONSTRUCT(&rtb_convertor, opal_convertor_t);
OBJ_CONSTRUCT(&rbuf_convertor, opal_convertor_t);
/* See lengthy comment in coll basic reduce about
explanation for how to malloc the extra buffer. Note
that we do not need a buffer big enough to hold "count"
instances of the datatype (i.e., big enough to hold the
entire user buffer) -- we only need to be able to hold
"segment_ddt_count" instances (i.e., the number of
instances that can be held in a single fragment) */
segsize = opal_datatype_span(&dtype->super, segment_ddt_count, &gap);
free_buffer = (char*)malloc(segsize);
if (NULL == free_buffer) {
return OMPI_ERR_OUT_OF_RESOURCE;
}
reduce_temp_buffer = free_buffer - gap;
/* Trickery here: we use a potentially smaller count than
the user count -- use the largest count that is <=
user's count that will fit within a single segment. */
if (OMPI_SUCCESS !=
(ret = opal_convertor_copy_and_prepare_for_recv(
ompi_mpi_local_convertor,
&(dtype->super),
segment_ddt_count,
reduce_temp_buffer,
0,
&rtb_convertor))) {
free(free_buffer);
return ret;
}
/* See if we need the rbuf_convertor */
if (size - 1 != rank) {
if (OMPI_SUCCESS !=
(ret = opal_convertor_copy_and_prepare_for_recv(
ompi_mpi_local_convertor,
&(dtype->super),
count,
rbuf,
0,
&rbuf_convertor))) {
free(free_buffer);
return ret;
}
}
}
/* If we're a) doing MPI_IN_PLACE (which means we're the root
-- wouldn't have gotten down here with MPI_IN_PLACE if we
weren't the root), and b) we're not rank (size-1), then we
need to copy the rbuf into a temporary buffer and use that
as the sbuf */
if (MPI_IN_PLACE == sbuf && (size - 1) != rank) {
segsize = opal_datatype_span(&dtype->super, count, &gap);
inplace_temp = (char*)malloc(segsize);
if (NULL == inplace_temp) {
if (NULL != free_buffer) {
free(free_buffer);
}
return OMPI_ERR_OUT_OF_RESOURCE;
}
sbuf = inplace_temp - gap;
ompi_datatype_copy_content_same_ddt(dtype, count, (char *)sbuf, (char *)rbuf);
} else {
inplace_temp = NULL;
}
/* Main loop over receiving / reducing fragments */
do {
flag_num = (data->mcb_operation_count %
mca_coll_sm_component.sm_comm_num_in_use_flags);
FLAG_SETUP(flag_num, flag, data);
FLAG_WAIT_FOR_IDLE(flag, reduce_root_flag_label);
FLAG_RETAIN(flag, size, data->mcb_operation_count);
++data->mcb_operation_count;
/* Loop over all the segments in this set */
segment_num =
flag_num * mca_coll_sm_component.sm_segs_per_inuse_flag;
max_segment_num =
(flag_num + 1) * mca_coll_sm_component.sm_segs_per_inuse_flag;
reduce_target = (((char*) rbuf) + (frag_num * extent * segment_ddt_count));
do {
/* Note that all the other coll modules reduce from
process (size-1) to 0, so that's the order we'll do
it here. */
/* Process (size-1) is the root (special case) */
if (size - 1 == rank) {
/* If we're the root *and* the first process to be
combined *and* this is the first segment in the
entire algorithm, then just copy the whole sbuf
to rbuf. That way, we never need to copy from
my sbuf again (i.e., do the copy all at once
since all the data is local, and then don't
worry about it for the rest of the
algorithm) */
if (first_operation) {
first_operation = false;
if (MPI_IN_PLACE != sbuf) {
ompi_datatype_copy_content_same_ddt(dtype, count,
reduce_target, (char*)sbuf);
}
}
}
/* Process (size-1) is not the root */
else {
/* Wait for the data to be copied into shmem, just
like any other non-root process */
index = &(data->mcb_data_index[segment_num]);
PARENT_WAIT_FOR_NOTIFY_SPECIFIC(size - 1, rank, index, max_data, reduce_root_parent_label1);
/* If the datatype is contiguous, just copy it
straight to the reduce_target */
if (NULL == free_buffer) {
memcpy(reduce_target, ((char*)index->mcbmi_data) +
(size - 1) * mca_coll_sm_component.sm_fragment_size, max_data);
}
/* If the datatype is noncontiguous, use the
rbuf_convertor to unpack it straight to the
rbuf */
else {
max_data = segment_ddt_bytes;
COPY_FRAGMENT_OUT(rbuf_convertor, size - 1, index,
iov, max_data);
}
}
/* Loop over all the remaining processes, receiving
and reducing them in order */
for (peer = size - 2; peer >= 0; --peer) {
/* Handle the case where the source is this
process (which, by definition, excludes the
sbuf_copied_to_rbuf case because that can
*only* happen when root==0). In this case, we
don't need to wait for the peer (i.e., me) to
copy into shmem -- just reduce directly from my
sbuf. */
if (rank == peer) {
ompi_op_reduce(op,
((char *) sbuf) +
frag_num * extent * segment_ddt_count,
reduce_target,
min(count_left, segment_ddt_count),
dtype);
}
/* Now handle the case where the source is not
this process. Wait for the process to copy to
the segment into shmem. */
else {
index = &(data->mcb_data_index[segment_num]);
PARENT_WAIT_FOR_NOTIFY_SPECIFIC(peer, rank,
index, max_data, reduce_root_parent_label2);
/* If we don't need an extra buffer, then do the
reduction operation on the fragment straight
from the shmem. */
if (NULL == free_buffer) {
ompi_op_reduce(op,
(index->mcbmi_data +
(peer * mca_coll_sm_component.sm_fragment_size)),
reduce_target,
min(count_left, segment_ddt_count),
dtype);
}
/* Otherwise, unpack the fragment to the temporary
buffer and then do the reduction from there */
else {
/* Unpack the fragment into my temporary
buffer */
max_data = segment_ddt_bytes;
COPY_FRAGMENT_OUT(rtb_convertor, peer, index,
iov, max_data);
opal_convertor_set_position(&rtb_convertor, &zero);
/* Do the reduction on this fragment */
ompi_op_reduce(op, reduce_temp_buffer,
reduce_target,
min(count_left, segment_ddt_count),
dtype);
}
} /* whether this process was me or not */
} /* loop over all proceses */
/* We've iterated through all the processes -- now we
move on to the next segment */
count_left -= segment_ddt_count;
bytes += segment_ddt_bytes;
++segment_num;
++frag_num;
reduce_target += extent * segment_ddt_count;
} while (bytes < total_size && segment_num < max_segment_num);
/* Root is now done with this set of segments */
FLAG_RELEASE(flag);
} while (bytes < total_size);
/* Kill the convertor, if we had one */
if (NULL != free_buffer) {
OBJ_DESTRUCT(&rtb_convertor);
OBJ_DESTRUCT(&rbuf_convertor);
free(free_buffer);
}
if (NULL != inplace_temp) {
free(inplace_temp);
}
}
/*********************************************************************
* Non-root
*********************************************************************/
else {
/* Here we get a convertor for the full count that the user
provided (as opposed to the convertor that the root got) */
opal_convertor_t sbuf_convertor;
OBJ_CONSTRUCT(&sbuf_convertor, opal_convertor_t);
if (OMPI_SUCCESS !=
(ret =
opal_convertor_copy_and_prepare_for_send(ompi_mpi_local_convertor,
&(dtype->super),
count,
sbuf,
0,
&sbuf_convertor))) {
return ret;
}
/* Loop over sending fragments to the root */
do {
flag_num = (data->mcb_operation_count %
mca_coll_sm_component.sm_comm_num_in_use_flags);
/* Wait for the root to mark this set of segments as
ours */
FLAG_SETUP(flag_num, flag, data);
FLAG_WAIT_FOR_OP(flag, data->mcb_operation_count, reduce_nonroot_flag_label);
++data->mcb_operation_count;
/* Loop over all the segments in this set */
segment_num =
flag_num * mca_coll_sm_component.sm_segs_per_inuse_flag;
max_segment_num =
(flag_num + 1) * mca_coll_sm_component.sm_segs_per_inuse_flag;
do {
index = &(data->mcb_data_index[segment_num]);
/* Copy from the user's buffer to my shared mem
segment */
max_data = segment_ddt_bytes;
COPY_FRAGMENT_IN(sbuf_convertor, index, rank, iov, max_data);
bytes += max_data;
/* Wait for the write to absolutely complete */
opal_atomic_wmb();
/* Tell my parent (always the reduction root -- we're
ignoring the mcb_tree parent/child relationships
here) that this fragment is ready */
CHILD_NOTIFY_PARENT(rank, root, index, max_data);
++segment_num;
} while (bytes < total_size && segment_num < max_segment_num);
/* We're finished with this set of segments */
FLAG_RELEASE(flag);
} while (bytes < total_size);
/* Kill the convertor */
OBJ_DESTRUCT(&sbuf_convertor);
}
/* All done */
return OMPI_SUCCESS;
}
#if WANT_REDUCE_NO_ORDER
/**
* Unordered shared memory reduction.
*
* This function performs the reduction in whatever order the operands
* arrive.
*/
static int reduce_no_order(const void *sbuf, void* rbuf, int count,
struct ompi_datatype_t *dtype,
struct ompi_op_t *op,
int root, struct ompi_communicator_t *comm,
mca_coll_base_module_t *module)
{
return OMPI_ERR_NOT_IMPLEMENTED;
}
#endif