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.\" $FreeBSD: head/lib/libc/sys/sched_get_priority_max.2 131504 2004-07-02 23:52:20Z ru $
.\"
.Dd March 12, 1998
.Dt SCHED_GET_PRIORITY_MAX 2
.Os
.Sh NAME
.Nm sched_get_priority_max ,
.Nm sched_get_priority_min ,
.Nm sched_rr_get_interval
.Nd get scheduling parameter limits
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sched.h
.Ft int
.Fn sched_get_priority_max "int policy"
.Ft int
.Fn sched_get_priority_min "int policy"
.Ft int
.Fn sched_rr_get_interval "pid_t pid" "struct timespec *interval"
.Sh DESCRIPTION
The
.Fn sched_get_priority_max
and
.Fn sched_get_priority_min
system calls return the appropriate maximum or minimum, respectively,
for the scheduling policy specified by
.Fa policy .
The
.Fn sched_rr_get_interval
system call updates the
.Fa timespec
structure referenced by the
.Fa interval
argument to contain the current execution time limit (i.e., time
quantum) for the process specified by
.Fa pid .
If
.Fa pid
is zero, the current execution time limit for the calling process is
returned.
.Pp
The value of
.Fa policy
should be one of the scheduling policy values defined in
.Fa <sched.h> :
.Bl -tag -width [SCHED_OTHER]
.It Bq Er SCHED_FIFO
First-in-first-out fixed priority scheduling with no round robin scheduling;
.It Bq Er SCHED_OTHER
The standard time sharing scheduler;
.It Bq Er SCHED_RR
Round-robin scheduling across same priority processes.
.El
.Sh RETURN VALUES
If successful, the
.Fn sched_get_priority_max
and
.Fn sched_get_priority_min
system calls shall return the appropriate maximum or minimum values,
respectively.
If unsuccessful, they shall return a value of -1 and set
.Fa errno
to indicate the error.
.Pp
.Rv -std sched_rr_get_interval
.Sh ERRORS
On failure
.Va errno
will be set to the corresponding value:
.Bl -tag -width Er
.It Bq Er EINVAL
The value of the
.Fa policy
argument does not represent a defined scheduling policy.
.It Bq Er ENOSYS
The
.Fn sched_get_priority_max ,
.Fn sched_get_priority_min ,
and
.Fn sched_rr_get_interval
system calls are not supported by the implementation.
.It Bq Er ESRCH
No process can be found corresponding to that specified by
.Fa pid .
.El
.Sh SEE ALSO
.Xr sched_getparam 2 ,
.Xr sched_getscheduler 2 ,
.Xr sched_setparam 2 ,
.Xr sched_setscheduler 2
.Sh STANDARDS
The
.Fn sched_get_priority_max ,
.Fn sched_get_priority_min ,
and
.Fn sched_rr_get_interval
system calls conform to
.St -p1003.1b-93 .