Skip to content

Instantly share code, notes, and snippets.

@mikeblas
Created September 1, 2023 01:44
Show Gist options
  • Save mikeblas/7f75f16c94652ba6c4317559ad315f86 to your computer and use it in GitHub Desktop.
Save mikeblas/7f75f16c94652ba6c4317559ad315f86 to your computer and use it in GitHub Desktop.
allocate pages of memory and dirty them up
#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;
}
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment