Preface

In embedded linux development board, memory and other resources are often limited. It is often necessary to query how much memory the program consumes. linux commands such as "free-m" can only query static residual memory. In other words, these commands do not query the real-time memory consumed by the program's running process.

code implementation

So a better and accurate way is to call the linux system API in the program code to get the remaining memory, through which the maximum memory needed in the real-time running of the program can be known.

There are usually two ways to get the remaining memory in code:

One is to call the pipeline interface. The sample code is as follows:

fp=popen("cat /proc/meminfo | grep MemTotal:|sed -e 's/.*:[^0-9]//'","r");
if(fp < 0)
{
    printf("Unable to read ram information\n");
    exit(1);
}

The other is to call the sysinfo interface. The sample code is as follows:

#include <stdio.h>
#include <linux/kernel.h>
#include <linux/unistd.h>
#include <sys/sysinfo.h>

int main(void)
{
    struct sysinfo s_info;
    int error = sysinfo(&s_info);
    printf("error0: %d, total: %lu free: %lu \n", error, s_info.totalram, s_info.freeram);
    func_call1(pcModelName);

    error = sysinfo(&s_info);
    printf("error1: %d, total: %lu free: %lu \n", error, s_info.totalram, s_info.freeram);

    int msg[500];
    for (int i = 0; i < 1; i++)
    {
        func_call2(pcSrcFile, msg);
        error = sysinfo(&s_info);
        printf("error2: %d, total: %lu free: %lu \n", error, s_info.totalram, s_info.freeram);

        func_call3(pcSrcFile, msg);
        error = sysinfo(&s_info);
        printf("error3: %d, total: %lu free: %lu \n", error, s_info.totalram, s_info.freeram);
    }

    func_call4();
    error = sysinfo(&s_info);
    printf("error4: %d, total: %lu free: %lu \n", error, s_info.totalram, s_info.freeram);
}

Result analysis

Following is the result of the second method running:

error0: 0, total: 256958464 free: 219029504
xxx xxx
error2: 0, total: 256958464 free: 159387648
xxx xxx
error3: 0, total: 256958464 free: 158969856
xxx xxx
error4: 0, total: 256958464 free: 163442688

As can be seen from the above results, the maximum (peak) memory value required during the running of the program is 219029504 - 158969856 = 60059648/(1024 * 1024) approximately = 57.277MB.