Swap performance testing

Question

I understand the general concept of swap memory, but I need to somehow build a program that forces the use of swap memory for performance testing and I don't know where to even begin.

Basically, I am going to install a flash memory card that will be used as swap space, and I want to test how the performance improves by doing so. I thought it would be easiest to make a simple program that uses multiple threads to test how well it handles multiple processes running simultaneously. Problem is, I just don't know enough about swap (or gathered enough insight from what i've read) to know how I can "force" these threads to use swap space.

Anyone have some solid suggestions on how I can approach this? I would be running this on a 64-bit linux OS, most likely Fedora 18.

Answer 1

I don't know if this is better way to archive what you want to do, but i used a C code like this

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


#define MB(size) ( (size) * 1024 * 1024 )

int main(){
    char *p;
    if((p = (char *)malloc(MB(256))) != NULL){
            memset(p, "A", MB(256));
            sleep(300);
    }
}

gcc -o mhog mhog.c
echo 1 > /proc/sys/vm/overcommit_memory

and run ./mhog many times in this way

./mhog &

When your server or computer will be in out of memory situation, you will see the begin used