
As discussed on https://github.com/mpi-forum/mpi-issues/issues/77#issuecomment-369663119 the conversion to double in the MPI_Wtime decrease the range and accuracy of the resulting timer. By setting the timer to 0 at the first usage we basically maintain the accuracy for 194 days even for gettimeofday. Signed-off-by: George Bosilca <bosilca@icl.utk.edu>
100 строки
3.2 KiB
C
100 строки
3.2 KiB
C
/*
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* Copyright (c) 2004-2007 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) 2004-2018 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) 2006-2014 Cisco Systems, Inc. All rights reserved.
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* Copyright (c) 2015 Research Organization for Information Science
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* and Technology (RIST). All rights reserved.
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* Copyright (c) 2017 IBM Corporation. All rights reserved.
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* Copyright (c) 2017 Los Alamos National Security, LLC. All rights
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* 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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#include "ompi_config.h"
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#ifdef HAVE_SYS_TIME_H
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#include <sys/time.h>
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#endif
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#include <stdio.h>
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#ifdef HAVE_TIME_H
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#include <time.h>
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#endif /* HAVE_TIME_H */
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#include MCA_timer_IMPLEMENTATION_HEADER
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#include "ompi/mpi/c/bindings.h"
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#include "ompi/runtime/mpiruntime.h"
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#if OMPI_BUILD_MPI_PROFILING
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#if OPAL_HAVE_WEAK_SYMBOLS
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#pragma weak MPI_Wtime = PMPI_Wtime
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#endif
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#define MPI_Wtime PMPI_Wtime
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/**
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* Have a base time set on the first call to wtime, to improve the range
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* and accuracy of the user visible timer.
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* More info: https://github.com/mpi-forum/mpi-issues/issues/77#issuecomment-369663119
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*/
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#if defined(__linux__) && OPAL_HAVE_CLOCK_GETTIME
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struct timespec ompi_wtime_time_origin = {.tv_sec = 0};
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#else
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struct timeval ompi_wtime_time_origin = {.tv_sec = 0};
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#endif
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#else /* OMPI_BUILD_MPI_PROFILING */
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#if defined(__linux__) && OPAL_HAVE_CLOCK_GETTIME
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extern struct timespec ompi_wtime_time_origin;
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#else
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extern struct timeval ompi_wtime_time_origin;
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#endif
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#endif
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double MPI_Wtime(void)
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{
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double wtime;
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/*
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* See https://github.com/open-mpi/ompi/issues/3003 to find out
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* what's happening here.
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*/
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#if 0
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#if OPAL_TIMER_CYCLE_NATIVE
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wtime = ((double) opal_timer_base_get_cycles()) / opal_timer_base_get_freq();
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#elif OPAL_TIMER_USEC_NATIVE
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wtime = ((double) opal_timer_base_get_usec()) / 1000000.0;
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#endif
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#else
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#if defined(__linux__) && OPAL_HAVE_CLOCK_GETTIME
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struct timespec tp;
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(void) clock_gettime(CLOCK_MONOTONIC, &tp);
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if( OPAL_UNLIKELY(0 == ompi_wtime_time_origin.tv_sec) ) {
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ompi_wtime_time_origin = tp;
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}
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wtime = (double)(tp.tv_nsec - ompi_wtime_time_origin.tv_nsec)/1.0e+9;
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wtime += (tp.tv_sec - ompi_wtime_time_origin.tv_sec);
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#else
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/* Fall back to gettimeofday() if we have nothing else */
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struct timeval tv;
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gettimeofday(&tv, NULL);
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if( OPAL_UNLIKELY(0 == ompi_wtime_time_origin.tv_sec) ) {
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ompi_wtime_time_origin = tv;
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}
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wtime = (double)(tv.tv_usec - ompi_wtime_time_origin.tv_usec) / 1.0e+6;
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wtime += (tv.tv_sec - ompi_wtime_time_origin.tv_sec);
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#endif
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#endif
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OPAL_CR_NOOP_PROGRESS();
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return wtime;
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}
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