sysinfo系统调用在linux上返回错误的加载平均值

Question

我有一个C程序打印一些系统统计信息.

#include <sys/sysinfo.h>
#include <stdio.h>

int main() {
  int days, hours, mins;
  struct sysinfo sys_info;

  if(sysinfo(&sys_info) != 0)
    perror("sysinfo");

  // Uptime
  days = sys_info.uptime / 86400;
  hours = (sys_info.uptime / 3600) - (days * 24);
  mins = (sys_info.uptime / 60) - (days * 1440) - (hours * 60);

  printf("Uptime: %ddays, %dhours, %dminutes, %ldseconds\n",
                      days, hours, mins, sys_info.uptime % 60);

  // Load Averages for 1,5 and 15 minutes
  printf("Load Avgs: 1min(%ld) 5min(%ld) 15min(%ld)\n",
          sys_info.loads[0], sys_info.loads[1], sys_info.loads[2]);

  printf("Total Ram: %lluk\tFree: %lluk\n",
                sys_info.totalram *(unsigned long long)sys_info.mem_unit / 1024,
                sys_info.freeram *(unsigned long long)sys_info.mem_unit/ 1024);


  // Number of processes currently running.
  printf("Number of processes: %d\n", sys_info.procs);

  return 0;
}

我的问题是负载平均值不同于/ proc/loadavg

./a.out 
Uptime: 1days, 4hours, 1minutes, 16seconds
Load Avgs: 1min(13248) 5min(14880) 15min(11840)
Total Ram: 2052956k Free: 188104k
Number of processes: 265

为什么？我打印13248但"top"或"cat/proc/loadavg"给出0.24.问题是什么？

Answer 1

该调用不会返回"错误"值.请注意,类型是整数,因此不能返回正常运行时打印的浮点数.

请参阅此主题以获取有关如何解释返回值以及如何转换为更熟悉的浮点数的调查.

我的猜测(在阅读链接之前)是它的表现为按比例增加65,535(2 ¹⁶),这似乎也是他们发现的结果.因此除以65536.0,或者更清洁(如注释中所指出的)使用SI_LOAD_SHIFT常量并除以(float)(1 << SI_LOAD_SHIFT).