linux sysinfo函数使用方法－－获取内存大小

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Linux中,sysinfo是用来获取系统相关信息的结构体。
函数声明和原型：
#include <sys/sysinfo.h>

int sysinfo(struct sysinfo *info);

结构体信息：
在Linux 2.3.16中，结构体的信息是（单位是字节）：

struct sysinfo {
long uptime;
/* 启动到现在经过的时间 */
unsigned long loads[3];

/* 1, 5, and 15 minute load averages */
unsigned long totalram; /* 总的可用的内存大小 */
unsigned long freeram; /* 还未被使用的内存大小 */
unsigned long sharedram; /* 共享的存储器的大小 */
unsigned long bufferram; /* 缓冲区大小 */
unsigned long totalswap; /* 交换区大小 */
unsigned long freeswap; /* 还可用的交换区大小 */
unsigned short procs; /* 当前进程数目 */
char _f[22]; /* 64字节的补丁结构 */
};

在Linux 2.3.23(i386), 2.3.48 (all architectures)中，结构体的信息是（单位是mem_unit字节）：

struct sysinfo {
long uptime; /* 启动到现在经过的时间 */
unsigned long loads[3];

/* 1, 5, and 15 minute load averages */
unsigned long totalram; /* 总的可用的内存大小 */
unsigned long freeram; /* 还未被使用的内存大小 */
unsigned long sharedram; /* 共享的存储器的大小*/
unsigned long bufferram; /* 共享的存储器的大小 */
unsigned long totalswap; /* 交换区大小 */
unsigned long freeswap; /* 还可用的交换区大小 */
unsigned short procs; /* 当前进程数目 */
unsigned long totalhigh; /* 总的高内存大小 */
unsigned long freehigh; /* 可用的高内存大小 */
unsigned int mem_unit; /* 以字节为单位的内存大小 */
char _f[20-2*sizeof(long)-sizeof(int)];

/* libc5的补丁
};

返回值：
操作成功返回0，错误返回-1；
样例：
#include <stdio.h>

#include <linux/unistd.h> /* 包含调用 _syscallX 宏等相关信息*/
#include <linux/kernel.h> /* 包含sysinfo结构体信息*/

_syscall1(int, sysinfo, struct sysinfo*, info);
//using namespace std;
int main(int argc, char *agrv[])
{
struct sysinfo s_info;
int error;

error = sysinfo(&s_info);
printf("\n\ncode error=%d\n",error);
printf("Uptime = %ds\nLoad: 1 min%d / 5 min %d / 15 min %d\n"
"RAM: total %d / free %d /shared%d\n"
"Memory in buffers = %d\nSwap:total%d/free%d\n"
"Number of processes = %d\n",
s_info.uptime, s_info.loads[0],
s_info.loads[1], s_info.loads[2],
s_info.totalram, s_info.freeram,
s_info.totalswap, s_info.freeswap,
s_info.procs );
return 0;
}

/*输出结果：
/home/chenhd/future> ./Sysinfo_1
code error=0
Uptime = 154s
Load: 1 min22976 / 5 min 13888 / 15 min 5408
RAM: total 128307200 / free 55656448 /shared263168000
Memory in buffers = 263168000
Swap:total50/free1073821804
Number of processes = 1073823352
/home/chenhd/future>
*/

// an example

int main()
{
FILE *fp;
char str[81];
memset(str,0,81);
fp=popen("cat /proc/meminfo | grep MemTotal:|sed -e 's/.*:[^0-9]//'","r");
if(fp < 0)
{
printf("无法读取ram信息\n");
exit(1);
}
fgets(str,80,fp);
fclose(fp);
if (cpuinfo != NULL)
{
strncpy(cpuinfo,str,80);
}
#include <linux/unistd.h> /* 包含调用 _syscallX 宏等相关信息*/

#include <linux/kernel.h> /* 包含sysinfo结构体信息*/
#include <sys/sysinfo.h>
struct sysinfo s_info;
int error;
error = sysinfo(&s_info);

gulong spd=atoi(str);
printf("您ram是%lu kb %s %lu\n",spd, str, s_info.totalram);
return spd;
}