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sched_getscheduler(3)
NAME
  sched_getscheduler - Returns the scheduling policy of a process (P1003.1b)

SYNOPSIS
  #include <sched.h>

  int sched_getscheduler (
  pid_t pid);

LIBRARY
  Realtime Library (librt.so, librt.a)

PARAMETERS
  pid Specifies the ID of the process for which the scheduling policy is to
      be obtained. If pid is zero, the scheduling policy of the calling
      process is obtained.

DESCRIPTION
  The sched_getscheduler function returns the current scheduling policy of a
  process. The values that can be returned are defined in the header file
  <sched.h>.

  The sched_setscheduler function changes the scheduling policy and priority
  of a process. Changing the scheduling policy and priority ensures that an
  application can determine more effectively when a process will run.

  The realtime scheduling policies are as follows:

  SCHED_FIFO
      Specifies the first-in, first-out (FIFO) scheduling policy

  SCHED_RR
      Specifies the round-robin (RR) scheduling policy

  SCHED_OTHER
      Specifies the standard timesharing scheduling policy

  The SCHED_FIFO and SCHED_RR scheduling policies are fixed-priority
  scheduling policies. You can specify a priority for your process and the
  scheduler will not adjust it. Setting priorities in conjunction with a
  SCHED_FIFO scheduling policy allows a critical process to run as soon as it
  is ready, for as long as it needs to run, because the process will preempt
  other lower-priority processes.

  The round-robin scheduling policy is similar to first in-first out, but
  also imposes a quantum on execution time. Use the sched_rr_get_interval
  function to determine the current quantum for process execution under the
  SCHED_RR scheduling policy.

  The scheduler adjusts process priorities running under the timesharing
  scheduling policy.

  No special privileges are needed to use the sched_getscheduler function.

RETURN VALUES
  On a successful call to sched_getscheduler, the scheduling policy of the
  process is returned. If there is an error, -1 is returned and errno is set
  to indicate the error.

ERRORS
  The sched_getscheduler function fails under the following condition:

  [ESRCH]
      No process can be found corresponding to that specified by pid.

SEE ALSO
  Functions: getpid(2), sched_getparam(3), sched_setparam(3),
  sched_setscheduler(3)

  Guide to Realtime Programming

Index for Section 3

Alphabetical listing for S

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