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1 perry 1 GETPRIORITY
2 !!!GETPRIORITY
3 NAME
4 SYNOPSIS
5 DESCRIPTION
6 RETURN VALUE
7 ERRORS
8 NOTE
9 CONFORMING TO
10 SEE ALSO
11 ----
12 !!NAME
13
14
15 getpriority, setpriority - get/set program scheduling priority
16 !!SYNOPSIS
17
18
19 __#include __
20 #include __
21
22
23 __int getpriority(int__ ''which''__, int__
24 ''who''__);
25 int setpriority(int__ ''which''__, int__
26 ''who''__, int__ ''prio''__);__
27 !!DESCRIPTION
28
29
30 The scheduling priority of the process, process group, or
31 user, as indicated by ''which'' and ''who'' is
32 obtained with the __getpriority__ call and set with the
33 __setpriority__ call. ''Which'' is one of
34 __PRIO_PROCESS__, __PRIO_PGRP__, or __PRIO_USER__,
35 and ''who'' is interpreted relative to ''which'' (a
36 process identifier for __PRIO_PROCESS__, process group
37 identifier for __PRIO_PGRP__, and a user ID for
38 __PRIO_USER__). A zero value of ''who'' denotes the
39 current process, process group, or user. ''Prio'' is a
40 value in the range -20 to 20. The default priority is 0;
41 lower priorities cause more favorable
42 scheduling.
43
44
45 The __getpriority__ call returns the highest priority
46 (lowest numerical value) enjoyed by any of the specified
47 processes. The __setpriority__ call sets the priorities
48 of all of the specified processes to the specified value.
49 Only the super-user may lower priorities.
50 !!RETURN VALUE
51
52
53 Since __getpriority__ can legitimately return the value
54 -1, it is necessary to clear the external variable
55 ''errno'' prior to the call, then check it afterwards to
56 determine if a -1 is an error or a legitimate value. The
57 __setpriority__ call returns 0 if there is no error, or
58 -1 if there is.
59 !!ERRORS
60
61
62 __ESRCH__
63
64
65 No process was located using the ''which'' and ''who''
66 values specified.
67
68
69 __EINVAL__
70
71
72 ''Which'' was not one of __PRIO_PROCESS__,
73 __PRIO_PGRP__, or __PRIO_USER__.
74
75
76 In addition to the errors indicated above,
77 __setpriority__ will fail if:
78
79
80 __EPERM__
81
82
83 A process was located, but neither its effective nor real
84 user ID matched the effective user ID of the
85 caller.
86
87
88 __EACCES__
89
90
91 A non super-user attempted to lower a process
92 priority.
93 !!NOTE
94
95
96 Including '''' is not required these
97 days, but increases portability. (Indeed,
98 '''' defines the ''rusage''
99 structure with fields of type ''struct timeval'' defined
100 in ''''.)
101 !!CONFORMING TO
102
103
104 SVr4, 4.4BSD (these function calls first appeared in
105 4.2BSD).
106 !!SEE ALSO
107
108
109 nice(1), fork(2),
110 renice(8)
111 ----
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