1SCHED_SETSCHEDULER(3P) POSIX Programmer's Manual SCHED_SETSCHEDULER(3P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
12 sched_setscheduler — set scheduling policy and parameters (REALTIME)
13
15 #include <sched.h>
16 int sched_setscheduler(pid_t pid, int policy,
18 const struct sched_param *param);
19
21 The sched_setscheduler() function shall set the scheduling policy and
22 scheduling parameters of the process specified by pid to policy and the
23 parameters specified in the sched_param structure pointed to by param,
24 respectively. The value of the sched_priority member in the sched_param
25 structure shall be any integer within the inclusive priority range for
26 the scheduling policy specified by policy. If the value of pid is neg‐
27 ative, the behavior of the sched_setscheduler() function is unspeci‐
28 fied.
29 The possible values for the policy parameter are defined in the
31 <sched.h> header.
32 If a process specified by pid exists, and if the calling process has
34 permission, the scheduling policy and scheduling parameters shall be
35 set for the process whose process ID is equal to pid.
36 If pid is zero, the scheduling policy and scheduling parameters shall
38 be set for the calling process.
39 The conditions under which one process has appropriate privileges to
41 change the scheduling parameters of another process are implementation-
42 defined.
43 Implementations may require that the requesting process have permission
45 to set its own scheduling parameters or those of another process.
46 Additionally, implementation-defined restrictions may apply as to the
47 appropriate privileges required to set the scheduling policy of the
48 process, or the scheduling policy of another process, to a particular
49 value.
50 The sched_setscheduler() function shall be considered successful if it
52 succeeds in setting the scheduling policy and scheduling parameters of
53 the process specified by pid to the values specified by policy and the
54 structure pointed to by param, respectively.
55 See Scheduling Policies for a description on how this function affects
57 the scheduling of the threads within the target process.
58 If the current scheduling policy for the target process is not
60 SCHED_FIFO, SCHED_RR, or SCHED_SPORADIC, the result is implementation-
61 defined; this case includes the SCHED_OTHER policy.
62 The specified sched_ss_repl_period shall be greater than or equal to
64 the specified sched_ss_init_budget for the function to succeed; if it
65 is not, then the function shall fail.
66 The value of sched_ss_max_repl shall be within the inclusive range
68 [1,{SS_REPL_MAX}] for the function to succeed; if not, the function
69 shall fail. It is unspecified whether the sched_ss_repl_period and
70 sched_ss_init_budget values are stored as provided by this function or
71 are rounded to align with the resolution of the clock being used.
72 This function is not atomic with respect to other threads in the
74 process. Threads may continue to execute while this function call is in
75 the process of changing the scheduling policy and associated scheduling
76 parameters for the underlying kernel-scheduled entities used by the
77 process contention scope threads.
78
80 Upon successful completion, the function shall return the former sched‐
81 uling policy of the specified process. If the sched_setscheduler()
82 function fails to complete successfully, the policy and scheduling
83 parameters shall remain unchanged, and the function shall return a
84 value of -1 and set errno to indicate the error.
85
87 The sched_setscheduler() function shall fail if:
88 EINVAL The value of the policy parameter is invalid, or one or more of
90 the parameters contained in param is outside the valid range for
91 the specified scheduling policy.
92 EPERM The requesting process does not have permission to set either or
94 both of the scheduling parameters or the scheduling policy of
95 the specified process.
96 ESRCH No process can be found corresponding to that specified by pid.
98 The following sections are informative.
100
102 None.
103
105 None.
106
108 None.
109
111 None.
112
114 Scheduling Policies, sched_getparam(), sched_getscheduler(), sched_set‐
115 param()
116 The Base Definitions volume of POSIX.1‐2017, <sched.h>
118
120 Portions of this text are reprinted and reproduced in electronic form
121 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
122 table Operating System Interface (POSIX), The Open Group Base Specifi‐
123 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
124 Electrical and Electronics Engineers, Inc and The Open Group. In the
125 event of any discrepancy between this version and the original IEEE and
126 The Open Group Standard, the original IEEE and The Open Group Standard
127 is the referee document. The original Standard can be obtained online
128 at http://www.opengroup.org/unix/online.html .
129 Any typographical or formatting errors that appear in this page are
131 most likely to have been introduced during the conversion of the source
132 files to man page format. To report such errors, see https://www.ker‐
133 nel.org/doc/man-pages/reporting_bugs.html .
134IEEE/The Open Group 2017 SCHED_SETSCHEDULER(3P)