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SCHED_SETSCHEDULER(3P) POSIX Programmer's Manual SCHED_SETSCHEDULER(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_setscheduler — set scheduling policy and parameters (REALTIME)
#include <sched.h>
int sched_setscheduler(pid_t pid, int policy,
const struct sched_param *param);
The sched_setscheduler() function shall set the scheduling policy and
scheduling parameters of the process specified by pid to policy and
the parameters specified in the sched_param structure pointed to by
param, respectively. The value of the sched_priority member in the
sched_param structure shall be any integer within the inclusive
priority range for the scheduling policy specified by policy. If the
value of pid is negative, the behavior of the sched_setscheduler()
function is unspecified.
The possible values for the policy parameter are defined in the
<sched.h> header.
If a process specified by 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 pid.
If pid is zero, the scheduling policy and scheduling parameters shall
be set for the calling process.
The conditions under which one process has appropriate privileges to
change the scheduling parameters of another process are
implementation-defined.
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.
The sched_setscheduler() function shall be considered successful if
it succeeds in setting the scheduling policy and scheduling
parameters of the process specified by pid to the values specified by
policy and the structure pointed to by param, respectively.
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 and associated
scheduling parameters for the underlying kernel-scheduled entities
used by the process contention scope threads.
Upon successful completion, the function shall return the former
scheduling policy of the specified process. If the
sched_setscheduler() function fails to complete successfully, the
policy and scheduling parameters shall remain unchanged, and the
function shall return a value of −1 and set errno to indicate the
error.
The sched_setscheduler() function shall fail if:
EINVAL The value of the policy parameter is invalid, or one or more
of the parameters contained in param is outside the valid
range for the specified scheduling policy.
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.
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_setparam(3p)
The Base Definitions volume of POSIX.1‐2008, sched.h(0p)
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) 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.unix.org/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 2013 SCHED_SETSCHEDULER(3P)
Pages that refer to this page: sched.h(0p), getpriority(3p), posix_spawn(3p), sched_getparam(3p), sched_get_priority_max(3p), sched_getscheduler(3p), sched_rr_get_interval(3p), sched_setparam(3p)