1 2 # include <stdio.h> 3 # include <math.h> 4 # include <limits.h> 5 # include <float.h> 6 #include <petscsys.h> 7 8 /* 9 * Program: Stream 10 * Programmer: Joe R. Zagar 11 * Revision: 4.0-BETA, October 24, 1995 12 * Original code developed by John D. McCalpin 13 * 14 * This program measures memory transfer rates in MB/s for simple 15 * computational kernels coded in C. These numbers reveal the quality 16 * of code generation for simple uncacheable kernels as well as showing 17 * the cost of floating-point operations relative to memory accesses. 18 * 19 * INSTRUCTIONS: 20 * 21 * 1) Stream requires a good bit of memory to run. Adjust the 22 * value of 'N' (below) to give a 'timing calibration' of 23 * at least 20 clock-ticks. This will provide rate estimates 24 * that should be good to about 5% precision. 25 */ 26 27 # define N 2000000 28 # define NTIMES 50 29 # define OFFSET 0 30 31 /* 32 * 3) Compile the code with full optimization. Many compilers 33 * generate unreasonably bad code before the optimizer tightens 34 * things up. If the results are unreasonably good, on the 35 * other hand, the optimizer might be too smart for me! 36 * 37 * Try compiling with: 38 * cc -O stream_d.c second.c -o stream_d -lm 39 * 40 * This is known to work on Cray, SGI, IBM, and Sun machines. 41 * 42 * 43 * 4) Mail the results to mccalpin@cs.virginia.edu 44 * Be sure to include: 45 * a) computer hardware model number and software revision 46 * b) the compiler flags 47 * c) all of the output from the test case. 48 * Thanks! 49 * 50 */ 51 52 # define HLINE "-------------------------------------------------------------\n" 53 54 # ifndef MIN 55 # define MIN(x,y) ((x)<(y) ? (x) : (y)) 56 # endif 57 # ifndef MAX 58 # define MAX(x,y) ((x)>(y) ? (x) : (y)) 59 # endif 60 61 static double a[N+OFFSET], 62 b[N+OFFSET], 63 c[N+OFFSET]; 64 /*double *a,*b,*c;*/ 65 66 static double mintime[4] = {FLT_MAX,FLT_MAX,FLT_MAX,FLT_MAX}; 67 68 static double bytes[4] = { 69 2 * sizeof(double) * N, 70 2 * sizeof(double) * N, 71 3 * sizeof(double) * N, 72 3 * sizeof(double) * N 73 }; 74 75 int main(int argc,char **args) 76 { 77 int quantum, checktick(void); 78 register int j, k; 79 double scalar, t, times[4][NTIMES],irate[4],rate[4]; 80 int rank,size,resultlen; 81 char hostname[MPI_MAX_PROCESSOR_NAME]; 82 MPI_Status status; 83 int ierr; 84 FILE *fd; 85 86 ierr = PetscInitialize(&argc,&args,NULL,NULL);if (ierr) return ierr; 87 ierr = MPI_Comm_rank(MPI_COMM_WORLD,&rank);if (ierr) return ierr; 88 ierr = MPI_Comm_size(MPI_COMM_WORLD,&size);if (ierr) return ierr; 89 90 for (j=0; j<MPI_MAX_PROCESSOR_NAME; j++) { 91 hostname[j] = 0; 92 } 93 ierr = MPI_Get_processor_name(hostname,&resultlen);if (ierr) return ierr; 94 if (!rank) { 95 for (j=1; j<size; j++) { 96 ierr = MPI_Recv(hostname,MPI_MAX_PROCESSOR_NAME,MPI_CHAR,j,0,MPI_COMM_WORLD,&status);if (ierr) return ierr; 97 } 98 } else { 99 ierr = MPI_Send(hostname,MPI_MAX_PROCESSOR_NAME,MPI_CHAR,0,0,MPI_COMM_WORLD);if (ierr) return ierr; 100 } 101 ierr = MPI_Barrier(MPI_COMM_WORLD); 102 103 /* --- SETUP --- determine precision and check timing --- */ 104 105 if (!rank) { 106 /*printf(HLINE); 107 printf("Array size = %d, Offset = %d\n" , N, OFFSET); 108 printf("Total memory required = %.1f MB.\n", (3 * N * BytesPerWord) / 1048576.0); 109 printf("Each test is run %d times, but only\n", NTIMES); 110 printf("the *best* time for each is used.\n"); 111 printf(HLINE); */ 112 } 113 114 /* Get initial value for system clock. */ 115 116 /* a = malloc(N*sizeof(double)); 117 b = malloc(N*sizeof(double)); 118 c = malloc(N*sizeof(double));*/ 119 for (j=0; j<N; j++) { 120 a[j] = 1.0; 121 b[j] = 2.0; 122 c[j] = 0.0; 123 } 124 125 if (!rank) { 126 if ((quantum = checktick()) >= 1) ; /* printf("Your clock granularity/precision appears to be %d microseconds.\n", quantum); */ 127 else ; /* printf("Your clock granularity appears to be less than one microsecond.\n");*/ 128 } 129 130 t = MPI_Wtime(); 131 for (j = 0; j < N; j++) a[j] = 2.0E0 * a[j]; 132 t = 1.0E6 * (MPI_Wtime() - t); 133 134 if (!rank) { 135 /* printf("Each test below will take on the order of %d microseconds.\n", (int) t); 136 printf(" (= %d clock ticks)\n", (int) (t/quantum)); 137 printf("Increase the size of the arrays if this shows that\n"); 138 printf("you are not getting at least 20 clock ticks per test.\n"); 139 printf(HLINE);*/ 140 } 141 142 /* --- MAIN LOOP --- repeat test cases NTIMES times --- */ 143 144 scalar = 3.0; 145 for (k=0; k<NTIMES; k++) 146 { 147 ierr = MPI_Barrier(MPI_COMM_WORLD); 148 times[0][k] = MPI_Wtime(); 149 /* should all these barriers be pulled outside of the time call? */ 150 ierr = MPI_Barrier(MPI_COMM_WORLD); 151 for (j=0; j<N; j++) c[j] = a[j]; 152 ierr = MPI_Barrier(MPI_COMM_WORLD); 153 times[0][k] = MPI_Wtime() - times[0][k]; 154 155 times[1][k] = MPI_Wtime(); 156 ierr = MPI_Barrier(MPI_COMM_WORLD); 157 for (j=0; j<N; j++) b[j] = scalar*c[j]; 158 ierr = MPI_Barrier(MPI_COMM_WORLD); 159 times[1][k] = MPI_Wtime() - times[1][k]; 160 161 times[2][k] = MPI_Wtime(); 162 ierr = MPI_Barrier(MPI_COMM_WORLD); 163 for (j=0; j<N; j++) c[j] = a[j]+b[j]; 164 ierr = MPI_Barrier(MPI_COMM_WORLD); 165 times[2][k] = MPI_Wtime() - times[2][k]; 166 167 times[3][k] = MPI_Wtime(); 168 ierr = MPI_Barrier(MPI_COMM_WORLD); 169 for (j=0; j<N; j++) a[j] = b[j]+scalar*c[j]; 170 ierr = MPI_Barrier(MPI_COMM_WORLD); 171 times[3][k] = MPI_Wtime() - times[3][k]; 172 } 173 174 /* --- SUMMARY --- */ 175 176 for (k=0; k<NTIMES; k++) 177 for (j=0; j<4; j++) mintime[j] = MIN(mintime[j], times[j][k]); 178 179 for (j=0; j<4; j++) irate[j] = 1.0E-06 * bytes[j]/mintime[j]; 180 ierr = MPI_Reduce(irate,rate,4,MPI_DOUBLE,MPI_SUM,0,MPI_COMM_WORLD); 181 if (ierr) printf("Error calling MPI\n"); 182 183 if (!rank) { 184 if (size == 1) { 185 printf("%d %11.4f Rate (MB/s)\n",size, rate[3]); 186 fd = fopen("flops","w"); 187 fprintf(fd,"%g\n",rate[3]); 188 fclose(fd); 189 } else { 190 double prate; 191 fd = fopen("flops","r"); 192 fscanf(fd,"%lg",&prate); 193 fclose(fd); 194 printf("%d %11.4f Rate (MB/s) %g \n", size, rate[3],rate[3]/prate); 195 } 196 } 197 PetscFinalize(); 198 return 0; 199 } 200 201 # define M 20 202 203 int checktick(void) 204 { 205 int i, minDelta, Delta; 206 double t1, t2, timesfound[M]; 207 208 /* Collect a sequence of M unique time values from the system. */ 209 210 for (i = 0; i < M; i++) { 211 t1 = MPI_Wtime(); 212 while (((t2=MPI_Wtime()) - t1) < 1.0E-6) ; 213 timesfound[i] = t1 = t2; 214 } 215 216 /* 217 * Determine the minimum difference between these M values. 218 * This result will be our estimate (in microseconds) for the 219 * clock granularity. 220 */ 221 222 minDelta = 1000000; 223 for (i = 1; i < M; i++) { 224 Delta = (int)(1.0E6 * (timesfound[i]-timesfound[i-1])); 225 minDelta = MIN(minDelta, MAX(Delta,0)); 226 } 227 228 return(minDelta); 229 } 230 231