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25.Dd March 12, 1998
26.Dt SCHED_GET_PRIORITY_MAX 2
27.Os
28.Sh NAME
29.Nm sched_get_priority_max ,
30.Nm sched_get_priority_min ,
31.Nm sched_rr_get_interval
32.Nd get scheduling parameter limits
33.Sh LIBRARY
34.Lb libc
35.Sh SYNOPSIS
36.In sched.h
37.Ft int
38.Fn sched_get_priority_max "int policy"
39.Ft int
40.Fn sched_get_priority_min "int policy"
41.Ft int
42.Fn sched_rr_get_interval "pid_t pid" "struct timespec *interval"
43.Sh DESCRIPTION
44The
45.Fn sched_get_priority_max
46and
47.Fn sched_get_priority_min
48system calls return the appropriate maximum or minimum, respectively,
49for the scheduling policy specified by
50.Fa policy .
51The
52.Fn sched_rr_get_interval
53system call updates the
54.Fa timespec
55structure referenced by the
56.Fa interval
57argument to contain the current execution time limit (i.e., time
58quantum) for the process specified by
59.Fa pid .
60If
61.Fa pid
62is zero, the current execution time limit for the calling process is
63returned.
64.Pp
65The value of
66.Fa policy
67should be one of the scheduling policy values defined in
68.Fa <sched.h> :
69.Bl -tag -width [SCHED_OTHER]
70.It Bq Er SCHED_FIFO
71First-in-first-out fixed priority scheduling with no round robin scheduling;
72.It Bq Er SCHED_OTHER
73The standard time sharing scheduler;
74.It Bq Er SCHED_RR
75Round-robin scheduling across same priority processes.
76.El
77.Sh RETURN VALUES
78If successful, the
79.Fn sched_get_priority_max
80and
81.Fn sched_get_priority_min
82system calls shall return the appropriate maximum or minimum values,
83respectively.
84If unsuccessful, they shall return a value of -1 and set
85.Fa errno
86to indicate the error.
87.Pp
88.Rv -std sched_rr_get_interval
89.Sh ERRORS
90On failure
91.Va errno
92will be set to the corresponding value:
93.Bl -tag -width Er
94.It Bq Er EINVAL
95The value of the
96.Fa policy
97argument does not represent a defined scheduling policy.
98.It Bq Er ENOSYS
99The
100.Fn sched_get_priority_max ,
101.Fn sched_get_priority_min ,
102and
103.Fn sched_rr_get_interval
104system calls are not supported by the implementation.
105.It Bq Er ESRCH
106No process can be found corresponding to that specified by
107.Fa pid .
108.El
109.Sh SEE ALSO
110.Xr sched_getparam 2 ,
111.Xr sched_getscheduler 2 ,
112.Xr sched_setparam 2 ,
113.Xr sched_setscheduler 2
114.Sh STANDARDS
115The
116.Fn sched_get_priority_max ,
117.Fn sched_get_priority_min ,
118and
119.Fn sched_rr_get_interval
120system calls conform to
121.St -p1003.1b-93 .
122