[嵌入式]嵌入式linux内存超载工具设计

一、介绍
在业务测试的时候需要测试极限条件下业务工作是否正常，所以需要写一些极限测试工具

二、原理
使用malloc函数分配

三、代码实现
memtest.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/time.h>
#include <signal.h>

volatile int timer_cnt = 0;
volatile int set_cnt = 0;
volatile int set_memuse = 0;


void fun()
{
	timer_cnt++;
	alarm(1);
}

int read_memuseinfo()
{
	int ret = 0;
 	char buf[64] = {'\0'};
    FILE *Stream;
    int MemFree = 0,Memtotal = 0;

//	printf("read_memuseinfo\n");
	
	Stream = popen("cat /proc/meminfo | grep MemTotal | awk {'print $2'}", "r");
    fread(buf, sizeof(char), sizeof(buf), Stream);
    Memtotal = atoi(buf); 
	pclose(Stream);
//	printf("read Memtotal %d\n", Memtotal);
	
    Stream = popen("cat /proc/meminfo | grep MemFree | awk {'print $2'}", "r");
    fread(buf, sizeof(char), sizeof(buf), Stream); 
    MemFree = atoi(buf);
	pclose(Stream);
//	printf("read MemFree %d\n", MemFree);
	
	ret = (Memtotal - MemFree) * 100 / Memtotal;
	printf("total:%d byte free:%d byte use:%d%\n", Memtotal, MemFree, ret);
	
	return ret;
}

int memget(int x)
{
	int memuse = 0;
	void *p = NULL;
	static char state = 0;
	int memsize = 0;

	//printf("memget\n");
	memuse = read_memuseinfo();
	while(memuse < x)
	{
		memuse = read_memuseinfo();
		if(memuse == NULL)
		{
			state++;
			printf("memget fail\n");
		}
			
		if(state > 6)
			state = 6;
		switch(state)
		{
			case 0:memsize = 1024*1024;break;//1M		
			case 1:memsize = 500*1024;break;//500k
			case 2:memsize = 100*1024;break;//100k
			case 3:memsize = 50*1024;break;//50k
			case 4:memsize = 10*1024;break;//10k
			case 5:memsize = 5*1024;break;//5k
				default:memsize = 1*1024;break;//1k
		}
		p = malloc(memsize);
		memset(p, 0, memsize);
	}

	return 0;
}

int main(int argc, char *argv[])
{
	int ret = 0;
	if(argc > 1)
	{
		set_cnt = atoi(argv[1]);
		printf("set timer %d s\n", set_cnt);
		set_memuse = atoi(argv[2]);
		printf("set_memuse %d s\n", set_memuse);
	}
	else
	{
		printf("parameter error\n");
		exit(-1);
	}
	
	signal(SIGALRM, fun);
	alarm(1);
	
	while(1)
	{	
		memget(set_memuse);
		if(timer_cnt > set_cnt)
			break;
	}
	printf("get mem finish\n");
	
	return 0;
}

编译
mipsel-linux-gcc memtest.c -o memget -w

运行
./memget 120 80&

现象
会在120s内，内存使用率提升到80%