1PTHREAD_GETSCHEDPARAM(3P) POSIX Programmer's Manual PTHREAD_GETSCHEDPARAM(3P)
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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.
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13 pthread_getschedparam, pthread_setschedparam — dynamic thread schedul‐
14 ing parameters access (REALTIME THREADS)
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17 #include <pthread.h>
18 int pthread_getschedparam(pthread_t thread, int *restrict policy,
20 struct sched_param *restrict param);
21 int pthread_setschedparam(pthread_t thread, int policy,
22 const struct sched_param *param);
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25 The pthread_getschedparam() and pthread_setschedparam() functions
26 shall, respectively, get and set the scheduling policy and parameters
27 of individual threads within a multi-threaded process to be retrieved
28 and set. For SCHED_FIFO and SCHED_RR, the only required member of the
29 sched_param structure is the priority sched_priority. For SCHED_OTHER,
30 the affected scheduling parameters are implementation-defined.
31 The pthread_getschedparam() function shall retrieve the scheduling pol‐
33 icy and scheduling parameters for the thread whose thread ID is given
34 by thread and shall store those values in policy and param, respec‐
35 tively. The priority value returned from pthread_getschedparam() shall
36 be the value specified by the most recent pthread_setschedparam(),
37 pthread_setschedprio(), or pthread_create() call affecting the target
38 thread. It shall not reflect any temporary adjustments to its priority
39 as a result of any priority inheritance or ceiling functions. The
40 pthread_setschedparam() function shall set the scheduling policy and
41 associated scheduling parameters for the thread whose thread ID is
42 given by thread to the policy and associated parameters provided in
43 policy and param, respectively.
44 The policy parameter may have the value SCHED_OTHER, SCHED_FIFO, or
46 SCHED_RR. The scheduling parameters for the SCHED_OTHER policy are
47 implementation-defined. The SCHED_FIFO and SCHED_RR policies shall have
48 a single scheduling parameter, priority.
49 If _POSIX_THREAD_SPORADIC_SERVER is defined, then the policy argument
51 may have the value SCHED_SPORADIC, with the exception for the
52 pthread_setschedparam() function that if the scheduling policy was not
53 SCHED_SPORADIC at the time of the call, it is implementation-defined
54 whether the function is supported; in other words, the implementation
55 need not allow the application to dynamically change the scheduling
56 policy to SCHED_SPORADIC. The sporadic server scheduling policy has the
57 associated parameters sched_ss_low_priority, sched_ss_repl_period,
58 sched_ss_init_budget, sched_priority, and sched_ss_max_repl. The spec‐
59 ified sched_ss_repl_period shall be greater than or equal to the speci‐
60 fied sched_ss_init_budget for the function to succeed; if it is not,
61 then the function shall fail. The value of sched_ss_max_repl shall be
62 within the inclusive range [1,{SS_REPL_MAX}] for the function to suc‐
63 ceed; if not, the function shall fail. It is unspecified whether the
64 sched_ss_repl_period and sched_ss_init_budget values are stored as pro‐
65 vided by this function or are rounded to align with the resolution of
66 the clock being used.
67 If the pthread_setschedparam() function fails, the scheduling parame‐
69 ters shall not be changed for the target thread.
70
72 If successful, the pthread_getschedparam() and pthread_setschedparam()
73 functions shall return zero; otherwise, an error number shall be
74 returned to indicate the error.
75
77 The pthread_setschedparam() function shall fail if:
78 ENOTSUP
80 An attempt was made to set the policy or scheduling parameters
81 to an unsupported value.
82 ENOTSUP
84 An attempt was made to dynamically change the scheduling policy
85 to SCHED_SPORADIC, and the implementation does not support this
86 change.
87 The pthread_setschedparam() function may fail if:
89 EINVAL The value specified by policy or one of the scheduling parame‐
91 ters associated with the scheduling policy policy is invalid.
92 EPERM The caller does not have appropriate privileges to set either
94 the scheduling parameters or the scheduling policy of the speci‐
95 fied thread.
96 EPERM The implementation does not allow the application to modify one
98 of the parameters to the value specified.
99 These functions shall not return an error code of [EINTR].
101 The following sections are informative.
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105 None.
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108 None.
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111 If an implementation detects use of a thread ID after the end of its
112 lifetime, it is recommended that the function should fail and report an
113 [ESRCH] error.
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116 None.
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119 pthread_setschedprio(), sched_getparam(), sched_getscheduler()
120 The Base Definitions volume of POSIX.1‐2008, <pthread.h>, <sched.h>
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124 Portions of this text are reprinted and reproduced in electronic form
125 from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
126 -- Portable Operating System Interface (POSIX), The Open Group Base
127 Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
128 cal and Electronics Engineers, Inc and The Open Group. (This is
129 POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
130 event of any discrepancy between this version and the original IEEE and
131 The Open Group Standard, the original IEEE and The Open Group Standard
132 is the referee document. The original Standard can be obtained online
133 at http://www.unix.org/online.html .
134 Any typographical or formatting errors that appear in this page are
136 most likely to have been introduced during the conversion of the source
137 files to man page format. To report such errors, see https://www.ker‐
138 nel.org/doc/man-pages/reporting_bugs.html .
139IEEE/The Open Group 2013 PTHREAD_GETSCHEDPARAM(3P)