功能描述：

    获取进程的资源使用信息。

    用法：

    #include

    #include

    int getrusage(int who, struct rusage *usage);    

    参数：

    who：可能选择有

    RUSAGE_SELF：获取当前进程的资源使用信息。

    RUSAGE_CHILDREN：获取子进程的资源使用信息。

    usage：指向存放资源使用信息的结构指针

    struct rusage {

     struct timeval ru_utime; /* user time used */

     struct timeval ru_stime; /* system time used */

     long ru_maxrss; /* maximum resident set size */

     long ru_ixrss; /* integral shared memory size */

     long ru_idrss; /* integral unshared data size */

     long ru_isrss; /* integral unshared stack size */

     long ru_minflt; /* page reclaims */

     long ru_majflt; /* page faults */

     long ru_nswap; /* swaps */

     long ru_inblock; /* block input operations */

     long ru_oublock; /* block output operations */

     long ru_msgsnd; /* messages sent */

     long ru_msgrcv; /* messages received */

     long ru_nsignals; /* signals received */

     long ru_nvcsw; /* voluntary context switches */

     long ru_nivcsw; /* involuntary context switches */

    };

    返回说明：

    成功执行时，返回0。失败返回-1，errno被设为以下的某个值

    EFAULT：usage指针指向的空间不可访问

    EINVAL：who参数无效