allocate pages of memory and dirty them up

swapper.cpp

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


typedef struct {
        int visitcount;
} pagestruct;



int main(int argc, char **argv)
{
        if (argc < 2)
        {
                printf("Usage: swapper <pages>\n\n");
                return 1;
        }

        // how many pages?
        int numPages = atoi(argv[1]);
        printf("%d pages is %d bytes\n", numPages, 4096L * numPages);

        // build table
        std::vector<int> indexes(numPages);
        for (int n = 0; n < numPages; n++)
                indexes[n] = n;
        for (int n = 0; n < numPages; n++)
        {
                int target = (rand() % (numPages - n)) + n;
                // printf("swap %d, %d\n", n, target);
                int t = indexes[n];
                std::swap(indexes[n], indexes[target]);
        }
        /*
        for (int n = 0; n < numPages; n++)
                printf("%d\n", indexes[n]);
        */
          // get the actual memory
        printf("Allocating %d pages ...\n", numPages);
        std::vector<pagestruct*> pages(numPages);
        for (int n = 0; n < numPages; n++)
        {
                pages[n] = (pagestruct*) calloc(1, 4096);
                if (pages[n] == nullptr)
                {
                        printf("Allocation failed!\n");
                        return 1;
                }
        }
        printf("Allocation successful!\n");

        // do something with it
        int visits = 0;
        while (true)
        {
                for (int n = 0; n < numPages; n++)
                {
                        pagestruct* p = pages[indexes[n]];
                        p->visitcount += 1;
                }
                visits += 1;
                if (visits % 100 == 0)
                {
                        for (int n = 0; n < numPages; n++)
                        {
                                if (pages[indexes[n]]->visitcount != visits)
                                {
                                        printf("got %d, expected %d\n", pages[indexes[n]], visits);
                                        return 1;
                                }
                        }
                        printf("done with %d visits\n", visits);
                }
        }

        // done


        return 0;
}