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Goktug
Asked: 2018-10-18 02:21:02 +0800 CST

流程的友好性和优先级

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根据我阅读的一些资源，nice 值低的进程具有更高的优先级。因为它具有更高的优先级，所以 CPU 会为该进程分配更多时间。

但是，这听起来有点奇怪，因为进程的优先级值是通过将 nice 值与 20 相加来计算的。

PR = NI + 20。这可以通过命令轻松查看top

根据这个公式，nice 值越高的进程优先级越高，但有些资源说nice 值低的进程优先级更高。

哪一个是真的？

process process-priority nice

1 个回答

  1. Best Answer

    根据这个公式，nice 值越高的进程优先级越高，但有些资源说nice 值低的进程优先级更高。

    关闭，但没有 cookie。优先级的数值高不代表优先级高。 top从 读取优先级/proc/<pid>/stat。请参阅man 5 proc该文件的说明：

    (18) priority  %ld
    (Explanation  for Linux 2.6) For processes running a real-time scheduling
    policy (policy below; see sched_setscheduler(2)),  this  is  the  negated
    scheduling  priority,  minus  one;  that  is, a number in the range -2 to
    -100, corresponding to real-time  priorities  1  to  99.   For  processes
    running  under  a  non-real-time  scheduling policy, this is the raw nice
    value (setpriority(2)) as represented in the kernel.  The  kernel  stores
    nice  values  as numbers in the range 0 (high) to 39 (low), corresponding
    to the user-visible nice range of -20 to 19.

    Before Linux 2.6,  this  was  a  scaled  value  based  on  the  scheduler
    weighting given to this process.

    所以：PR 从 0（高）到 39（低）。

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