scheduling

sched_getscheduler(3)					     Library Functions Manual					     sched_getscheduler(3)

NAME

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

LIBRARY

       Realtime Library (librt.so, librt.a)

SYNOPSIS

       #include <sched.h>

       int sched_getscheduler (
       pid_t pid);

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.

RELATED INFORMATION

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

       Guide to Realtime Programming delim off

															     sched_getscheduler(3)