sched_setscheduler.3p (5619B)
- '\" et
- .TH SCHED_SETSCHEDULER "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
- sched_setscheduler
- \(em set scheduling policy and parameters
- (\fBREALTIME\fP)
- .SH SYNOPSIS
- .LP
- .nf
- #include <sched.h>
- .P
- int sched_setscheduler(pid_t \fIpid\fP, int \fIpolicy\fP,
- const struct sched_param *\fIparam\fP);
- .fi
- .SH DESCRIPTION
- The
- \fIsched_setscheduler\fR()
- function shall set the scheduling policy and scheduling parameters
- of the process specified by
- .IR pid
- to
- .IR policy
- and the parameters specified in the
- .BR sched_param
- structure pointed to by
- .IR param ,
- respectively. The value of the
- .IR sched_priority
- member in the
- .BR sched_param
- structure shall be any integer within the inclusive priority range
- for the scheduling policy specified by
- .IR policy .
- If the value of
- .IR pid
- is negative, the behavior of the
- \fIsched_setscheduler\fR()
- function is unspecified.
- .P
- The possible values for the
- .IR policy
- parameter are defined in the
- .IR <sched.h>
- header.
- .P
- If a process specified by
- .IR pid
- exists, and if the calling process has permission, the scheduling
- policy and scheduling parameters shall be set for the process whose
- process ID is equal to
- .IR pid .
- .P
- If
- .IR pid
- is zero, the scheduling policy and scheduling parameters shall be
- set for the calling process.
- .P
- The conditions under which one process has appropriate privileges to
- change the scheduling parameters of another process are
- implementation-defined.
- .P
- Implementations may require that the requesting process have permission
- to set its own scheduling parameters or those of another process.
- Additionally, implementation-defined restrictions may apply as to the
- appropriate privileges required to set the scheduling
- policy of the process, or the scheduling policy of another process,
- to a particular value.
- .P
- The
- \fIsched_setscheduler\fR()
- function shall be considered successful if it succeeds in setting the
- scheduling policy and scheduling parameters of the process specified by
- .IR pid
- to the values specified by
- .IR policy
- and the structure pointed to by
- .IR param ,
- respectively.
- .P
- See
- .IR "Scheduling Policies"
- for a description on how this function affects the scheduling of the
- threads within the target process.
- .P
- If the current scheduling policy for the target process is not
- SCHED_FIFO, SCHED_RR,
- or SCHED_SPORADIC,
- the result is implementation-defined; this case includes the
- SCHED_OTHER policy.
- .P
- 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.
- .P
- The value of
- .IR sched_ss_max_repl
- shall be within the inclusive range [1,{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
- This function is not atomic with respect to other threads in the
- process. Threads may continue to execute while this function call is in
- the process of changing the scheduling policy and associated scheduling
- parameters for the underlying kernel-scheduled entities used by the
- process contention scope threads.
- .SH "RETURN VALUE"
- Upon successful completion, the function shall return the former
- scheduling policy of the specified process. If the
- \fIsched_setscheduler\fR()
- function fails to complete successfully, the policy and scheduling
- parameters shall remain unchanged, and the function shall return a
- value of \-1 and set
- .IR errno
- to indicate the error.
- .SH ERRORS
- The
- \fIsched_setscheduler\fR()
- function shall fail if:
- .TP
- .BR EINVAL
- The value of the
- .IR policy
- parameter is invalid, or one or more of the parameters contained in
- .IR param
- is outside the valid range for the specified scheduling policy.
- .TP
- .BR EPERM
- The requesting process does not have permission to set either or both
- of the scheduling parameters or the scheduling policy of the specified
- process.
- .TP
- .BR ESRCH
- No process can be found corresponding to that specified by
- .IR pid .
- .LP
- .IR "The following sections are informative."
- .SH EXAMPLES
- None.
- .SH "APPLICATION USAGE"
- None.
- .SH RATIONALE
- None.
- .SH "FUTURE DIRECTIONS"
- None.
- .SH "SEE ALSO"
- .IR "Scheduling Policies",
- .IR "\fIsched_getparam\fR\^(\|)",
- .IR "\fIsched_getscheduler\fR\^(\|)",
- .IR "\fIsched_setparam\fR\^(\|)"
- .P
- The Base Definitions volume of POSIX.1\(hy2017,
- .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 .