1-batch.c

#include <stdio.h> 
#include <stdlib.h>
#include <time.h>

#define KB 1024
#define MB 1024 * 1024

int main() {
    unsigned int steps = 256 * 1024 * 1024;
    static int arr[4 * 1024 * 1024];
    int lengthMod;
    unsigned int i;
    double timeTaken;
    clock_t start;
    int sizes[] = { 
        1 * KB, 4 * KB, 8 * KB, 16 * KB, 32 * KB, 64 * KB, 128 * KB, 256 * KB,
        512 * KB, 1 * MB, 1.5 * MB, 2 * MB, 2.5 * MB, 3 * MB, 3.5 * MB, 4 * MB
    };
    int results[sizeof(sizes)/sizeof(int)];
    int s;

    // for each size to test for ... 
    for (s = 0; s < sizeof(sizes)/sizeof(int); s++) {
	    lengthMod = sizes[s] - 1;
	    start = clock();
	    for (i = 0; i < steps; i++) {
	        arr[(i * 16) & lengthMod] *= 10;
            arr[(i * 16) & lengthMod] /= 10;
	    }

	    timeTaken = (double)(clock() - start)/CLOCKS_PER_SEC;
        printf("%d, %.8f \n", sizes[s] / 1024, timeTaken);
    }

    return 0;
}

1-single.c

#include <stdio.h> 
#include <stdlib.h>
#include <time.h>

#define KB 1024
#define MB 1024 * 1024

int main() {
    unsigned int steps = 512 * 1024 * 1024;
    static int arr[4 * 1024 * 1024];
    int lengthMod = 512 * KB - 1;
    unsigned int i;
    double timeTaken;
    clock_t start;

    start = clock();
    for (i = 0; i < steps; i++) {
        arr[(i * 16) & lengthMod] *= 10;
        arr[(i * 16) & lengthMod] /= 10;
    }
    timeTaken = (double)(clock() - start)/CLOCKS_PER_SEC;
    printf("%d, %.8f \n", (lengthMod+1)/ 1024, timeTaken);

    return 0;
}

cache-profile.c

#include <stdio.h> 
#include <stdlib.h>
#include <time.h>

#define KB 1024
#define MB 1024 * 1024

long long wall_clock_time() {
	#ifdef __linux__
		struct timespec tp;
		clock_gettime(CLOCK_REALTIME, &tp);
		return (long long)(tp.tv_nsec + (long long)tp.tv_sec * 1000000000ll);
	#else
		#warning "Your timer resoultion might be too low. Compile on Linux and link with librt"
		struct timeval tv;
		gettimeofday(&tv, NULL);
		return (long long)(tv.tv_usec * 1000 + (long long)tv.tv_sec * 1000000000ll);
	#endif
}

int main() {
    unsigned int steps = 1024 * 1024 * 1024;
    static int arr[4 * 1024 * 1024];
    int lengthMod;
    unsigned int i;
    int sizes[] = { 
        1 * KB, 4 * KB, 8 * KB, 16 * KB, 32 * KB, 64 * KB, 128 * KB, 256 * KB, 
        384 * KB, 512 * KB, 0.75 * MB, 1 * MB, 1.25 * MB, 1.5 * MB, 1.75 * MB, 
        2 * MB, 2.25 * MB, 2.5 * MB, 2.75 * MB, 3 * MB, 3.25 * MB, 3.5 * MB,
        3.75 * MB, 4 * MB
    };
    int results[sizeof(sizes)/sizeof(int)];
    int s;
    long long start, end;
    float timeTaken;

    // for each size to test for ... 
    for (s = 0; s < sizeof(sizes)/sizeof(int); s++) {
	    lengthMod = sizes[s] - 1;
	    start = wall_clock_time();
	    for (i = 0; i < steps; i++) {
	        arr[(i * 4) & lengthMod]++;
	    }
	    end = wall_clock_time();
	    timeTaken = ((float)(end - start))/1000000000;
        printf("%d, %1.4f \n", sizes[s] / 1024, timeTaken);
    }

    return 0;  
}

try.c

int main() {
    unsigned int steps = 256 * 1024 * 1024;
    static int arr[4 * 1024 * 1024];
    int lengthMod;
    unsigned int i;
    double timeTaken;
    clock_t start;
    int size; // in KB
    int increment = 16; // +4KB each iteration

    // for each size to test for ... 
    for (size = 4; (size * KB) <= (sizeof(arr)); size += increment) {
	    lengthMod = (size * KB) - 1;
	    start = clock();
	    for (i = 0; i < steps; i++) {
	        arr[(i * 16) & lengthMod]++;
	    }

	    timeTaken = (double)(clock() - start)/CLOCKS_PER_SEC;
	    printf("%d, %.8f \n", (lengthMod+1) / 1024, timeTaken);
    }
}