nice(2) 맨 페이지 - 윈디하나의 솔라나라

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nice(2)

nice(2)                          System Calls                          nice(2)



NAME
       nice - change priority of a process

SYNOPSIS
       #include <unistd.h>

       int nice(int incr);

DESCRIPTION
       The nice() function allows a process to change its priority. The invok‐
       ing process must be in a scheduling class that supports the nice().


       The nice() function adds the value of incr to the  nice  value  of  the
       calling  process.  A  process's nice value is a non-negative number for
       which a greater positive value results in lower CPU priority.


       A maximum nice value of (2 * NZERO) −1 and a minimum nice  value  of  0
       are  imposed  by  the  system.  NZERO  is  defined in <limits.h> with a
       default value of 20. Requests for values above or  below  these  limits
       result  in  the nice value being set to the corresponding limit. A nice
       value of 40 is treated as 39.


       Calling the nice() function has no effect on the priority of  processes
       or threads with policy SCHED_FIFO or SCHED_RR.


       Only  a  process  with the {PRIV_PROC_PRIOCNTL} privilege can lower the
       nice value.

RETURN VALUES
       Upon successful completion, nice() returns the  new  nice  value  minus
       NZERO.  Otherwise,  −1  is  returned,  the  process's nice value is not
       changed, and errno is set to indicate the error.

ERRORS
       The nice() function will fail if:

       EINVAL    The nice() function is called by a process  in  a  scheduling
                 class other than time-sharing or fixed-priority.


       EPERM     The  incr  argument  is  negative  or greater than 40 and the
                 {PRIV_PROC_PRIOCNTL} privilege is not asserted in the  effec‐
                 tive set of the calling process.


USAGE
       The priocntl(2) function is a more general interface to scheduler func‐
       tions.


       Since −1 is a permissible return value in a  successful  situation,  an
       application  wishing  to check for error situations should set errno to
       0, then call nice(), and if it returns −1, check to  see  if  errno  is
       non-zero.

ATTRIBUTES
       See attributes(7) for descriptions of the following attributes:


       tab()  box; cw(2.75i) |cw(2.75i) lw(2.75i) |lw(2.75i) ATTRIBUTE TYPEAT‐
       TRIBUTE VALUE _ Interface  StabilityCommitted  _  MT-LevelAsync-Signal-
       Safe _ StandardSee standards(7).


SEE ALSO
       nice(1),  exec(2),  priocntl(2), getpriority(3C), attributes(7), privi‐
       leges(7), standards(7)



Oracle Solaris 11.4               1 Apr 2004                           nice(2)
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