000f9eed4d
This commit updates the entire codebase to use specific opal types for all atomic variables. This is a change from the prior atomic support which required the use of the volatile keyword. This is the first step towards implementing support for C11 atomics as that interface requires the use of types declared with the _Atomic keyword. Signed-off-by: Nathan Hjelm <hjelmn@lanl.gov>
125 строки
4.3 KiB
C
125 строки
4.3 KiB
C
/*
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* Copyright (c) 2004-2005 The Trustees of Indiana University and Indiana
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* University Research and Technology
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* Corporation. All rights reserved.
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* Copyright (c) 2004-2014 The University of Tennessee and The University
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* of Tennessee Research Foundation. All rights
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* reserved.
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* Copyright (c) 2004-2005 High Performance Computing Center Stuttgart,
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* University of Stuttgart. All rights reserved.
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* Copyright (c) 2004-2005 The Regents of the University of California.
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* All rights reserved.
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* Copyright (c) 2015 Cisco Systems, Inc. All rights reserved.
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* $COPYRIGHT$
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*
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* Additional copyrights may follow
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*
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* $HEADER$
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*/
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/** @file */
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#include "ompi_config.h"
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#include "ompi/constants.h"
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#include "ompi/communicator/communicator.h"
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#include "ompi/mca/coll/coll.h"
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#include "opal/sys/atomic.h"
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#include "coll_sm.h"
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/**
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* Shared memory barrier.
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*
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* Tree-based algorithm for a barrier: a fan in to rank 0 followed by
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* a fan out using the barrier segments in the shared memory area.
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*
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* There are 2 sets of barrier buffers -- since there can only be, at
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* most, 2 outstanding barriers at any time, there is no need for more
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* than this. The generalized in-use flags, control, and data
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* segments are not used.
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*
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* The general algorithm is for a given process to wait for its N
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* children to fan in by monitoring a uint32_t in its barrier "in"
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* buffer. When this value reaches N (i.e., each of the children have
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* atomically incremented the value), then the process atomically
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* increases the uint32_t in its parent's "in" buffer. Then the
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* process waits for the parent to set a "1" in the process' "out"
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* buffer. Once this happens, the process writes a "1" in each of its
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* children's "out" buffers, and returns.
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*
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* There's corner cases, of course, such as the root that has no
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* parent, and the leaves that have no children. But that's the
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* general idea.
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*/
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int mca_coll_sm_barrier_intra(struct ompi_communicator_t *comm,
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mca_coll_base_module_t *module)
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{
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int rank, buffer_set;
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mca_coll_sm_comm_t *data;
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uint32_t i, num_children;
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volatile uint32_t *me_in, *me_out, *children = NULL;
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opal_atomic_uint32_t *parent;
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int uint_control_size;
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mca_coll_sm_module_t *sm_module = (mca_coll_sm_module_t*) module;
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/* Lazily enable the module the first time we invoke a collective
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on it */
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if (!sm_module->enabled) {
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int ret;
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if (OMPI_SUCCESS != (ret = ompi_coll_sm_lazy_enable(module, comm))) {
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return ret;
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}
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}
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uint_control_size =
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mca_coll_sm_component.sm_control_size / sizeof(uint32_t);
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data = sm_module->sm_comm_data;
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rank = ompi_comm_rank(comm);
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num_children = data->mcb_tree[rank].mcstn_num_children;
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buffer_set = ((data->mcb_barrier_count++) % 2) * 2;
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me_in = &data->mcb_barrier_control_me[buffer_set];
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me_out = (uint32_t*)
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(((char*) me_in) + mca_coll_sm_component.sm_control_size);
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/* Wait for my children to write to my *in* buffer */
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if (0 != num_children) {
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/* Get children *out* buffer */
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children = data->mcb_barrier_control_children + buffer_set +
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uint_control_size;
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SPIN_CONDITION(*me_in == num_children, exit_label1);
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*me_in = 0;
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}
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/* Send to my parent and wait for a response (don't poll on
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parent's out buffer -- that would cause a lot of network
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traffic / contention / faults / etc. Instead, children poll on
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local memory and therefore only num_children messages are sent
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across the network [vs. num_children *each* time all the
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children poll] -- i.e., the memory is only being polled by one
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process, and it is only changed *once* by an external
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process) */
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if (0 != rank) {
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/* Get parent *in* buffer */
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parent = &data->mcb_barrier_control_parent[buffer_set];
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opal_atomic_add (parent, 1);
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SPIN_CONDITION(0 != *me_out, exit_label2);
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*me_out = 0;
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}
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/* Send to my children */
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for (i = 0; i < num_children; ++i) {
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children[i * uint_control_size * 4] = 1;
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}
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/* All done! End state of the control segment:
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me_in: 0
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me_out: 0
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*/
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return OMPI_SUCCESS;
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}
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