c - 我应该调用什么 API 来获得系统正常运行时间？

Question

我想在基于 linux 的系统上运行的 C 应用程序中获取系统正常运行时间。我不想调用 uptime(1) 并解析输出，我想调用我怀疑存在的底层 C API。有谁知道有没有这样的调用，或者 uptime(1) 只是简单地处理从 wtmp 获得的记录？

Answer 1

您要查找的系统调用是 sysinfo()。

在 sys/sysinfo.h 中定义

它的签名是: int sysinfo(struct sysinfo *info)

自内核 2.4 以来，结构如下所示:

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 */
};

玩得开心!