156 lines
2.8 KiB
C
156 lines
2.8 KiB
C
#include <limits.h>
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#include <time.h>
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#include <stdio.h>
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#include <mpi.h>
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#include <stdlib.h>
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#include <math.h>
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#include <unistd.h>
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static double
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get_time()
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{
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struct timespec tv;
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if(clock_gettime(CLOCK_MONOTONIC, &tv) != 0)
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{
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perror("clock_gettime failed");
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exit(EXIT_FAILURE);
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}
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return (double)(tv.tv_sec) * 1.0e-9 +
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(double)tv.tv_nsec;
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}
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static int
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cmp_double(const void *pa, const void *pb)
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{
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double a, b;
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a = *(const double *) pa;
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b = *(const double *) pb;
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if(a < b)
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return -1;
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else if(a > b)
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return 1;
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else
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return 0;
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}
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/* Called by rank 0 */
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static void
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get_offset(double *timetable, char (*hosttable)[HOST_NAME_MAX], int nproc, int nsamples)
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{
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int i, j;
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double median, mean, var, std;
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double *offset;
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double *delta;
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offset = malloc(nproc * sizeof(double));
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delta = malloc(nsamples * sizeof(double));
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if(!offset || !delta)
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{
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perror("malloc");
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exit(EXIT_FAILURE);
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}
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/* We use as ref the clock in rank 0 */
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printf("%-10s %-20s %-20s %-20s\n", "rank", "hostname", "offset_median", "offset_std");
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for(i=0; i<nproc; i++)
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{
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for(j=0; j<nsamples; j++)
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delta[j] = timetable[j] - timetable[i*nsamples + j];
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mean = 0.0;
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var = 0.0;
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qsort(delta, sizeof(*delta), nsamples, cmp_double);
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median = delta[nsamples / 2];
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for(j=0; j<nsamples; j++)
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{
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//printf("%f\n", delta[j]);
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mean += delta[j];
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}
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mean /= nsamples;
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for(j=0; j<nsamples; j++)
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{
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var += (delta[j] - mean) * (delta[j] - mean);
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}
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var /= (double) (nsamples - 1);
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std = sqrt(var);
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offset[i] = mean;
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printf("%-10d %-20s %-20.0f %-20f\n", i, hosttable[i], median, std);
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}
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free(offset);
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free(delta);
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}
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int
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main(int argc, char *argv[])
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{
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double *t;
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double *timetable;
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int i, rank, nprocs, nsamples;
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char (*hosttable)[HOST_NAME_MAX];
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MPI_Init(&argc, &argv);
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if(!argv[1])
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nsamples = 100;
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else
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nsamples = atoi(argv[1]);
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MPI_Comm_rank(MPI_COMM_WORLD, &rank);
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MPI_Comm_size(MPI_COMM_WORLD, &nprocs);
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timetable = calloc(nsamples * nprocs, sizeof(double));
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hosttable = calloc(nprocs, sizeof(*hosttable));
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t = calloc(nsamples, sizeof(double));
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if(!timetable || !t || !hosttable)
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{
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perror("calloc");
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exit(EXIT_FAILURE);
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}
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/* Warm up iterations */
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for(i=0; i<20; i++)
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{
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MPI_Barrier(MPI_COMM_WORLD);
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get_time();
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}
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for(i=0; i<nsamples; i++)
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{
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MPI_Barrier(MPI_COMM_WORLD);
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t[i] = get_time();
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}
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if(gethostname(hosttable[rank], HOST_NAME_MAX) != 0)
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{
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perror("gethostname");
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exit(EXIT_FAILURE);
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}
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MPI_Gather(hosttable[rank], sizeof(*hosttable), MPI_CHAR,
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hosttable[0], sizeof(*hosttable), MPI_CHAR,
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0, MPI_COMM_WORLD);
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MPI_Gather(t, nsamples, MPI_DOUBLE,
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timetable, nsamples, MPI_DOUBLE,
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0, MPI_COMM_WORLD);
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if(rank == 0)
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get_offset(timetable, hosttable, nprocs, nsamples);
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free(hosttable);
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free(timetable);
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free(t);
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MPI_Finalize();
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return 0;
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}
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