pthread_getschedparam.3p (6115B)
- '\" et
- .TH PTHREAD_GETSCHEDPARAM "3P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual"
- .\"
- .SH PROLOG
- This manual page is part of the POSIX Programmer's Manual.
- The Linux implementation of this interface may differ (consult
- the corresponding Linux manual page for details of Linux behavior),
- or the interface may not be implemented on Linux.
- .\"
- .SH NAME
- pthread_getschedparam,
- pthread_setschedparam
- \(em dynamic thread scheduling parameters access
- (\fBREALTIME THREADS\fP)
- .SH SYNOPSIS
- .LP
- .nf
- #include <pthread.h>
- .P
- int pthread_getschedparam(pthread_t \fIthread\fP, int *restrict \fIpolicy\fP,
- struct sched_param *restrict \fIparam\fP);
- int pthread_setschedparam(pthread_t \fIthread\fP, int \fIpolicy\fP,
- const struct sched_param *\fIparam\fP);
- .fi
- .SH DESCRIPTION
- The
- \fIpthread_getschedparam\fR()
- and
- \fIpthread_setschedparam\fR()
- functions shall, respectively, get and set the scheduling policy and
- parameters of individual threads within a multi-threaded process to be
- retrieved and set. For SCHED_FIFO and SCHED_RR,
- the only required member of the
- .BR sched_param
- structure is the priority
- .IR sched_priority .
- For SCHED_OTHER,
- the affected scheduling parameters are implementation-defined.
- .P
- The
- \fIpthread_getschedparam\fR()
- function shall retrieve the scheduling policy and scheduling parameters
- for the thread whose thread ID is given by
- .IR thread
- and shall store those values in
- .IR policy
- and
- .IR param ,
- respectively. The priority value returned from
- \fIpthread_getschedparam\fR()
- shall be the value specified by the most recent
- \fIpthread_setschedparam\fR(),
- \fIpthread_setschedprio\fR(),
- or
- \fIpthread_create\fR()
- call affecting the target thread. It shall not reflect any temporary
- adjustments to its priority as a result of any priority inheritance or
- ceiling functions. The
- \fIpthread_setschedparam\fR()
- function shall set the scheduling policy and associated scheduling
- parameters for the thread whose thread ID is given by
- .IR thread
- to the policy and associated parameters provided in
- .IR policy
- and
- .IR param ,
- respectively.
- .P
- The
- .IR policy
- parameter may have the value SCHED_OTHER, SCHED_FIFO, or SCHED_RR. The
- scheduling parameters for the SCHED_OTHER policy are
- implementation-defined. The SCHED_FIFO and SCHED_RR policies shall
- have a single scheduling parameter,
- .IR priority .
- .P
- If _POSIX_THREAD_SPORADIC_SERVER is defined, then the
- .IR policy
- argument may have the value SCHED_SPORADIC, with the exception for the
- \fIpthread_setschedparam\fR()
- function that if the scheduling policy was not SCHED_SPORADIC at the
- time of the call, it is implementation-defined whether the function
- is supported; in other words, the implementation need not allow the
- application to dynamically change the scheduling policy to
- SCHED_SPORADIC. The sporadic server scheduling policy has the
- associated parameters
- .IR sched_ss_low_priority ,
- .IR sched_ss_repl_period ,
- .IR sched_ss_init_budget ,
- .IR sched_priority ,
- and
- .IR sched_ss_max_repl .
- The specified
- .IR sched_ss_repl_period
- shall be greater than or equal to the specified
- .IR sched_ss_init_budget
- for the function to succeed; if it is not, then the function shall
- fail. The value of
- .IR sched_ss_max_repl
- shall be within the inclusive range [1,\c
- {SS_REPL_MAX}]
- for the function to succeed; if not, the function shall fail.
- It is unspecified whether the
- .IR sched_ss_repl_period
- and
- .IR sched_ss_init_budget
- values are stored as provided by this function or are rounded to
- align with the resolution of the clock being used.
- .P
- If the
- \fIpthread_setschedparam\fR()
- function fails, the scheduling parameters shall not be changed
- for the target thread.
- .SH "RETURN VALUE"
- If successful, the
- \fIpthread_getschedparam\fR()
- and
- \fIpthread_setschedparam\fR()
- functions shall return zero; otherwise, an error number shall be
- returned to indicate the error.
- .SH ERRORS
- The
- \fIpthread_setschedparam\fR()
- function shall fail if:
- .TP
- .BR ENOTSUP
- An attempt was made to set the policy or scheduling parameters to an
- unsupported value.
- .TP
- .BR ENOTSUP
- An attempt was made to dynamically change the scheduling policy to
- SCHED_SPORADIC, and the implementation does not support this change.
- .P
- The
- \fIpthread_setschedparam\fR()
- function may fail if:
- .TP
- .BR EINVAL
- The value specified by
- .IR policy
- or one of the scheduling parameters associated with the scheduling
- policy
- .IR policy
- is invalid.
- .TP
- .BR EPERM
- The caller does not have appropriate privileges to set either the
- scheduling parameters or the scheduling policy of the specified
- thread.
- .TP
- .BR EPERM
- The implementation does not allow the application to modify
- one of the parameters to the value specified.
- .P
- These functions shall not return an error code of
- .BR [EINTR] .
- .LP
- .IR "The following sections are informative."
- .SH EXAMPLES
- None.
- .SH "APPLICATION USAGE"
- None.
- .SH RATIONALE
- If an implementation detects use of a thread ID after the end of its
- lifetime, it is recommended that the function should fail and report an
- .BR [ESRCH]
- error.
- .SH "FUTURE DIRECTIONS"
- None.
- .SH "SEE ALSO"
- .IR "\fIpthread_setschedprio\fR\^(\|)",
- .IR "\fIsched_getparam\fR\^(\|)",
- .IR "\fIsched_getscheduler\fR\^(\|)"
- .P
- The Base Definitions volume of POSIX.1\(hy2017,
- .IR "\fB<pthread.h>\fP",
- .IR "\fB<sched.h>\fP"
- .\"
- .SH COPYRIGHT
- Portions of this text are reprinted and reproduced in electronic form
- from IEEE Std 1003.1-2017, Standard for Information Technology
- -- Portable Operating System Interface (POSIX), The Open Group Base
- Specifications Issue 7, 2018 Edition,
- Copyright (C) 2018 by the Institute of
- Electrical and Electronics Engineers, Inc and The Open Group.
- In the event of any discrepancy between this version and the original IEEE and
- The Open Group Standard, the original IEEE and The Open Group Standard
- is the referee document. The original Standard can be obtained online at
- http://www.opengroup.org/unix/online.html .
- .PP
- Any typographical or formatting errors that appear
- in this page are most likely
- to have been introduced during the conversion of the source files to
- man page format. To report such errors, see
- https://www.kernel.org/doc/man-pages/reporting_bugs.html .