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PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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SCHED_SETPARAM(3P) POSIX Programmer's Manual SCHED_SETPARAM(3P)
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.
sched_setparam — set scheduling parameters (REALTIME)
#include <sched.h>
int sched_setparam(pid_t pid, const struct sched_param *param);
The sched_setparam() function shall set the scheduling parameters
of the process specified by pid to the values specified by the
sched_param structure pointed to by param. The value of the
sched_priority member in the sched_param structure shall be any
integer within the inclusive priority range for the current
scheduling policy of the process specified by pid. Higher
numerical values for the priority represent higher priorities. If
the value of pid is negative, the behavior of the sched_setparam()
function is unspecified.
If a process specified by pid exists, and if the calling process
has permission, the scheduling parameters shall be set for the
process whose process ID is equal to pid.
If pid is zero, the scheduling parameters shall be set for the
calling process.
The conditions under which one process has permission to change
the scheduling parameters of another process are implementation-
defined.
Implementations may require the requesting process to have
appropriate privileges to set its own scheduling parameters or
those of another process.
See Scheduling Policies for a description on how this function
affects the scheduling of the threads within the target process.
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.
The specified sched_ss_repl_period shall be greater than or equal
to the specified sched_ss_init_budget for the function to succeed;
if it is not, then the function shall fail.
The value of 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
sched_ss_repl_period and 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.
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 for the
underlying kernel-scheduled entities used by the process
contention scope threads.
If successful, the sched_setparam() function shall return zero.
If the call to sched_setparam() is unsuccessful, the priority
shall remain unchanged, and the function shall return a value of
-1 and set errno to indicate the error.
The sched_setparam() function shall fail if:
EINVAL One or more of the requested scheduling parameters is
outside the range defined for the scheduling policy of the
specified pid.
EPERM The requesting process does not have permission to set the
scheduling parameters for the specified process, or does
not have appropriate privileges to invoke sched_setparam().
ESRCH No process can be found corresponding to that specified by
pid.
The following sections are informative.
None.
None.
None.
None.
Scheduling Policies, sched_getparam(3p), sched_getscheduler(3p),
sched_setscheduler(3p)
The Base Definitions volume of POSIX.1‐2017, sched.h(0p)
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 .
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 .
IEEE/The Open Group 2017 SCHED_SETPARAM(3P)
Pages that refer to this page: sched.h(0p), posix_spawn(3p), sched_getparam(3p), sched_get_priority_max(3p), sched_getscheduler(3p), sched_rr_get_interval(3p), sched_setscheduler(3p)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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