lustre/tests/write_disjoint.c

   1 /* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
   2  * vim:expandtab:shiftwidth=8:tabstop=8:
   3  *
   4  * Each loop does 3 things:
   5  *   - rank 0 truncates to 0
   6  *   - all ranks agree on a random chunk size
   7  *   - all ranks race to write their pattern to their chunk of the file
   8  *   - rank 0 makes sure that the resulting file size is ranks * chunk size
   9  *   - rank 0 makes sure that everyone's patterns went to the right place
  10  *
  11  * compile: mpicc -g -Wall -o write_disjoint write_disjoint.c
  12  * run:     mpirun -np N -machlist <hostlist file> write_disjoint
  13  *  or:     pdsh -w <N hosts> write_disjoint
  14  *  or:     prun -n N [-N M] write_disjoint
  15  */
  16 #include <stdlib.h>
  17 #include <stdio.h>
  18 #include <sys/types.h>
  19 #include <sys/stat.h>
  20 #include <fcntl.h>
  21 #include <string.h>
  22 #include <errno.h>
  23 #include <unistd.h>
  24 #include <stdarg.h>
  25 #include "mpi.h"
  26
  27
  28 #define FILENAME "/mnt/lustre/write_disjoint"
  29 #define CHUNK_MAX_SIZE 123456
  30
  31 int rprintf(int rank, int loop, const char *fmt, ...)
  32 {
  33         va_list       ap;
  34
  35         printf("rank %d, loop %d: ", rank, loop);
  36
  37         va_start(ap, fmt);
  38
  39         vprintf(fmt, ap);
  40
  41         MPI_Finalize();
  42         exit(1);
  43 }
  44
  45 int main (int argc, char *argv[]) {
  46          int i, n, fd, chunk_size, file_size;
  47          int rank, noProcessors, done;
  48          off_t offset;
  49          char **chunk_buf;
  50          char *read_buf;
  51          struct stat stat_buf;
  52          ssize_t ret;
  53
  54          MPI_Init(&argc, &argv);
  55          MPI_Comm_size(MPI_COMM_WORLD, &noProcessors);
  56          MPI_Comm_rank(MPI_COMM_WORLD, &rank);
  57
  58          chunk_buf = malloc(noProcessors * sizeof(chunk_buf[0]));
  59          for (i=0; i < noProcessors; i++) {
  60                 chunk_buf[i] = malloc(CHUNK_MAX_SIZE);
  61                 memset(chunk_buf[i], 'A'+ i, CHUNK_MAX_SIZE);
  62          }
  63          read_buf = malloc(noProcessors * CHUNK_MAX_SIZE);
  64
  65          if (rank == 0) {
  66                 fd = open(FILENAME, O_WRONLY|O_CREAT|O_TRUNC, 0666);
  67                 if (fd < 0)
  68                         rprintf(rank, -1, "open() returned %s\n",
  69                                 strerror(errno));
  70          }
  71          MPI_Barrier(MPI_COMM_WORLD);
  72
  73          fd = open(FILENAME, O_RDWR);
  74          if (fd < 0)
  75                  rprintf(rank, -1, "open() returned %s\n", strerror(errno));
  76
  77          for (n=0; n < 1000 ; n++) {
  78                  /* reset the environment */
  79                  if (rank == 0) {
  80                          ret = truncate(FILENAME, 0);
  81                          if (ret != 0)
  82                                  rprintf(rank, n, "truncate() returned %s\n",
  83                                          strerror(errno) );
  84                  }
  85                  chunk_size = rand() % CHUNK_MAX_SIZE;
  86
  87                  if (n % 1000 == 0 && rank == 0)
  88                          printf("loop %d: chunk_size %d\n", n, chunk_size);
  89
  90                  MPI_Barrier(MPI_COMM_WORLD);
  91
  92                  /* Do the race */
  93                  offset = rank * chunk_size;
  94                  lseek(fd, offset, SEEK_SET);
  95
  96                  done = 0;
  97                  do {
  98                         ret = write(fd, chunk_buf[rank]+done, chunk_size-done);
  99                         if (ret < 0)
 100                                  rprintf(rank, n, "write() returned %s\n",
 101                                          strerror(errno));
 102                         done += ret;
 103                  } while (done != chunk_size);
 104
 105                  MPI_Barrier(MPI_COMM_WORLD);
 106
 107                  /* Check the result */
 108                  if (rank == 0) {
 109                          lseek(fd, 0, SEEK_SET);
 110
 111                          /* quick check */
 112                          stat(FILENAME, &stat_buf);
 113                          file_size = stat_buf.st_size;
 114                          if (file_size != chunk_size * noProcessors)
 115                                   rprintf(rank, n, "invalid file size %d"
 116                                           " instead of %d\n", file_size,
 117                                           chunk_size * noProcessors);
 118
 119                         done = 0;
 120                         do {
 121                                 ret = read(fd, read_buf + done,
 122                                            (chunk_size * noProcessors) - done);
 123                                 if (ret < 0)
 124                                         rprintf(rank, n, "read returned %s\n",
 125                                                 strerror(errno));
 126
 127                                 done += ret;
 128                         } while (done != chunk_size * noProcessors);
 129
 130                         for (i = 0; i < noProcessors; i++) {
 131                                 char command[4096];
 132                                 int j;
 133                                 if (!memcmp(read_buf + (i * chunk_size),
 134                                            chunk_buf[i], chunk_size))
 135                                         continue;
 136
 137                                 printf("rank %d, loop %d: chunk %d corrupted "
 138                                        "with chunk_size %d\n", rank, n, i,
 139                                        chunk_size);
 140                                 printf("(ranks: page boundry, chunk boundry, "
 141                                        "page boundry)\n");
 142                                 for (j = 1 ; j < noProcessors; j++) {
 143                                         int b = j * chunk_size;
 144                                         printf("\t%c -> %c: %d %d %d\n",
 145                                                'A' + j - 1, 'A' + j,
 146                                                b & ~(4096-1), b,
 147                                                (b + 4096) & ~(4096-1));
 148                                 }
 149
 150                                 sprintf(command, "od -Ad -a %s", FILENAME);
 151                                 system(command);
 152                                 MPI_Finalize();
 153                                 exit(1);
 154                         }
 155                 }
 156         }
 157
 158         printf("Finished after %d loops\n", n);
 159         MPI_Finalize();
 160         return 0;
 161 }