Question

我有一个打印一些系统统计信息的C程序。

#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与/ proc / loadavg

不同

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

为什么呢？我打印13248但“top”或“cat / proc / loadavg”给出0.24。有什么问题？

Answer 1

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。

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，请参阅this thread。

我的猜测（在阅读链接之前）是它表示为按比例缩放65,535（2 ¹⁶），这似乎也是他们发现的。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)。

sysinfo系统调用在linux上返回错误的加载平均值

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