How Can I Accurately Retrieve a C Program's Runtime Memory Usage on Linux?

Retrieving Runtime Memory Usage in C with /proc/pid

In C , obtaining information about a program's memory usage at runtime can be challenging. Despite attempts using getrusage(), the poster consistently encountered zero values. An alternative approach exists that involves querying files in the /proc/pid directory.

On Linux systems, /proc/pid contains process-specific information, including memory usage. One of the most reliable files for this purpose is /proc/self/stat. By parsing this file, we can extract the following fields:

• vsize: Program's virtual memory size in kilobytes (KB)
• rss: Program's resident set size in KB (amount of physical memory currently being used)

To retrieve these values, we can utilize the process_mem_usage() function:

void process_mem_usage(double& vm_usage, double& resident_set)
{
    // Parse /proc/self/stat
    ifstream stat_stream("/proc/self/stat");
    stat_stream >> ... >> vsize >> rss;
    stat_stream.close();

    // Convert to KB
    long page_size_kb = sysconf(_SC_PAGE_SIZE) / 1024;
    vm_usage     = vsize / 1024.0;
    resident_set = rss * page_size_kb;
}

Within our main() function, we can use process_mem_usage() to print the virtual memory usage and resident set size:

int main()
{
    double vm, rss;
    process_mem_usage(vm, rss);
    cout << "VM: " << vm << "; RSS: " << rss << endl;
}

Using this approach, we can accurately obtain the memory usage information of the current program at runtime.

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