嵌入式linux中很多内存资源都比较小，所以很多程序中在malloc时就需要提前知道内存剩余的大小
下面是一种调用 sysinfo接口来实现。

示例代码如下：

#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];int i = 0;for(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);
}