【sysinfo系统调用】

功能描述：
获取系统总体统计信息。

用法：
#include

int sysinfo(struct sysinfo *info);

参数：
info：指向sysinfo结构的指针，原型如下，Linux版本必须>=2.3.23(i386)，或者>=2.3.48(其它平台)。

struct sysinfo {
long uptime; /* Seconds since boot */
unsigned long loads[3]; /* 1, 5, and 15 minute load averages */
unsigned long totalram; /* Total usable main memory size */
unsigned long freeram; /* Available memory size */
unsigned long sharedram; /* Amount of shared memory */
unsigned long bufferram; /* Memory used by buffers */
unsigned long totalswap; /* Total swap space size */
unsigned long freeswap; /* swap space still available */
unsigned short procs; /* Number of current processes */
unsigned long totalhigh; /* Total high memory size */
unsigned long freehigh; /* Available high memory size */
unsigned int mem_unit; /* Memory unit size in bytes */
char _f[20-2*sizeof(long)-sizeof(int)]; /* Padding for libc5 */
};

返回说明：
成功执行时，返回0。失败返回-1，errno被设为EFAULT。