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1. Address Spaces

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2. Sharing Memory

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3. Code, Heap, Stack

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4. Experiment

va.c

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

int main(int argc, char *argv[]) {
    printf("location of code : %p\n", main);
    printf("location of heap : %p\n", malloc(100e6));
    int x = 3;
    printf("location of stack: %p\n", &x);
    return 0;
}

Sample output:

location of code : 0x55aa16a896fa
location of heap : 0x7f9c83599010
location of stack: 0x7ffddc28c204

note: stack/1e9 = 140728, i.e. 140 TB

try: static data

try commands: free, ps, pmap, top, lscpu; also see: /proc/<pid>/maps, /proc/cpuinfo

Homework Q3: Create a little program that uses a certain amount of memory, called memory-user.c. This program should take one command-line argument: the number of megabytes of memory it will use. When run, it should allocate an array, and constantly stream through the array, touching each entry. The program should do this indefinitely, or, perhaps, for a certain amount of time also specified at the command line.

alternative: see malloc() example