Commit 9b5553a5a46045658faf15680d4272f8e446fd84
1 parent
51366efbad
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master
Memory access time
Showing 1 changed file with 45 additions and 0 deletions Side-by-side Diff
memory_access_time.c
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9b5553a
| 1 | +#include<stdio.h> | |
| 2 | +#include <sys/time.h> | |
| 3 | +#include <stdlib.h> | |
| 4 | + | |
| 5 | +#define KB 1024 | |
| 6 | +#define MB 1024 * KB | |
| 7 | +#define MAX_ARRAY_SIZE 32*MB | |
| 8 | +#define STRIDE_SIZE 16 | |
| 9 | +#define CPU_FREQ 900 | |
| 10 | + | |
| 11 | +typedef unsigned long long int u64; | |
| 12 | + | |
| 13 | +u64 access_time_1(u64 size, int stride_size){ | |
| 14 | + struct timeval start, end; | |
| 15 | + struct timezone tz; | |
| 16 | + | |
| 17 | + int *array = (int *)malloc(size); | |
| 18 | + int len = (size)/sizeof(int); | |
| 19 | + unsigned int i; | |
| 20 | + | |
| 21 | + gettimeofday(&start, &tz); | |
| 22 | + for(i=0; i < MAX_ARRAY_SIZE; i++) { | |
| 23 | + array[( i * stride_size) % len]++; | |
| 24 | + } | |
| 25 | + gettimeofday(&end, &tz); | |
| 26 | + | |
| 27 | + free(array); | |
| 28 | + return ((end.tv_sec * 1e6) + end.tv_usec - (start.tv_sec * 1e6) - start.tv_usec); | |
| 29 | +} | |
| 30 | + | |
| 31 | +int main() | |
| 32 | +{ | |
| 33 | + int i, j; | |
| 34 | + | |
| 35 | + for (j = 4; j <= 32; j*=2) { | |
| 36 | + printf("Stride size: %u\n", j); | |
| 37 | + for (i = 1024; i <= 32 * MB; i*=2) { | |
| 38 | + u64 access_time = access_time_1(i, j); | |
| 39 | + u64 overhead = 10; | |
| 40 | + double avg = (access_time * 1000.0)/(2 * MAX_ARRAY_SIZE); | |
| 41 | + printf("Size: %uKB access: %lluus, avg: %gns\n", i >> 10, access_time, avg - overhead); | |
| 42 | + } | |
| 43 | + } | |
| 44 | + return 0; | |
| 45 | +} |