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openmpi/ompi/tools/mpisync/mpigclock.c

169 строки
5.6 KiB
C
Исходник Обычный вид История

/*
* Copyright (c) 2010-2011, Siberian State University of Telecommunications
* and Information Sciences. All rights reserved.
* Copyright (c) 2010-2011, A.V. Rzhanov Institute of Semiconductor Physics SB RAS.
* All rights reserved.
*
* mpigclock.c: MPI clock synchronization.
* http://mpiperf.cpct.sibsutis.ru/index.php
*
* Copyright (C) 2011 Mikhail Kurnosov <mkurnosov@gmail.com>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* Neither the name of the the copyright holders nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* $COPYRIGHT$
2015-06-24 06:59:57 +03:00
*
* Additional copyrights may follow
2015-06-24 06:59:57 +03:00
*
* $HEADER$
*/
#include <stdio.h>
#include <stdlib.h>
#include <mpi.h>
#include "mpigclock.h"
#include "hpctimer.h"
#define INVALIDTIME -1.0
#define MPIGCLOCK_RTTMIN_NOTCHANGED_MAX 100
#define MPIGCLOCK_MSGTAG 128
static double mpigclock_measure_offset_adaptive(MPI_Comm comm, int root, int peer, double *min_rtt, double root_offset);
/*
* mpigclock_sync_linear: Clock synchronization algorithm with O(n) steps.
*/
double mpigclock_sync_linear(MPI_Comm comm, int root, double *rtt)
{
int peer, rank, commsize;
double ret = 0;
MPI_Comm_rank(comm, &rank);
MPI_Comm_size(comm, &commsize);
for (peer = 1; peer < commsize; peer++) {
MPI_Barrier(comm);
if (rank == root || rank == peer) {
ret = mpigclock_measure_offset_adaptive(comm, root, peer, rtt, 0.0);
}
}
return ret;
}
/*
* mpigclock_sync_log: Clock synchronization algorithm with O(logn) steps.
* rtt argumrnt does not have a meaning
*/
double mpigclock_sync_log(MPI_Comm comm, int root, double *rtt)
{
int peer, rank, commsize;
double root_offset = 0;
double ret = 0;
MPI_Comm_rank(comm, &rank);
MPI_Comm_size(comm, &commsize);
/* I am a peer */
if (rank != root) {
root = (rank - 1) / 2;
MPI_Recv(&root_offset, 1, MPI_DOUBLE, root, MPIGCLOCK_MSGTAG, comm, MPI_STATUS_IGNORE);
ret = mpigclock_measure_offset_adaptive(comm, root, rank, rtt, root_offset);
}
root_offset = ret;
/* I am a root */
*rtt = 0;
peer = 2 * rank + 1;
if (peer < commsize) {
MPI_Send(&root_offset, 1, MPI_DOUBLE, peer, MPIGCLOCK_MSGTAG, comm);
mpigclock_measure_offset_adaptive(comm, rank, peer, rtt, root_offset);
}
*rtt = 0;
peer = 2 * rank + 2;
if (peer < commsize) {
MPI_Send(&root_offset, 1, MPI_DOUBLE, peer, MPIGCLOCK_MSGTAG, comm);
mpigclock_measure_offset_adaptive(comm, rank, peer, rtt, root_offset);
}
return ret;
}
/* mpigclock_measure_offset_adaptive: Measures clock's offset of peer. */
static double mpigclock_measure_offset_adaptive(MPI_Comm comm, int root, int peer, double *min_rtt, double root_offset)
{
int rank, commsize, rttmin_notchanged = 0;
double starttime, stoptime, peertime, rtt, rttmin = 1E12,
invalidtime = INVALIDTIME, offset;
MPI_Comm_rank(comm, &rank);
MPI_Comm_size(comm, &commsize);
offset = 0.0;
for (;;) {
if (rank != root) {
/* Peer process */
starttime = hpctimer_wtime();
MPI_Send(&starttime, 1, MPI_DOUBLE, root, MPIGCLOCK_MSGTAG, comm);
MPI_Recv(&peertime, 1, MPI_DOUBLE, root, MPIGCLOCK_MSGTAG, comm,
MPI_STATUS_IGNORE);
stoptime = hpctimer_wtime();
rtt = stoptime - starttime;
if (rtt < rttmin) {
rttmin = rtt;
rttmin_notchanged = 0;
offset = peertime - rtt / 2.0 - starttime;
} else {
if (++rttmin_notchanged == MPIGCLOCK_RTTMIN_NOTCHANGED_MAX) {
MPI_Send(&invalidtime, 1, MPI_DOUBLE, root, MPIGCLOCK_MSGTAG,
comm);
break;
}
}
} else {
/* Root process */
MPI_Recv(&starttime, 1, MPI_DOUBLE, peer, MPIGCLOCK_MSGTAG, comm,
MPI_STATUS_IGNORE);
peertime = hpctimer_wtime() + root_offset;
if (starttime < 0.0) {
break;
}
MPI_Send(&peertime, 1, MPI_DOUBLE, peer, MPIGCLOCK_MSGTAG, comm);
}
} /* for */
if( rank != root ){
*min_rtt = rttmin;
} else {
rtt = 0.0;
}
return offset;
}