SCHED_SETPARAM(3)          POSIX Programmer's Manual         SCHED_SETPARAM(3)



PROLOG
       This manual page is part of the POSIX Programmer's Manual.  The OS
       implementation of this interface may differ (consult the corresponding
       OS manual page for details of OS behavior), or the interface may not be
       implemented on OS.

NAME
       sched_setparam -- set scheduling parameters (REALTIME)

SYNOPSIS
       #include <sched.h>

       int sched_setparam(pid_t pid, const struct sched_param *param);

DESCRIPTION
       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.

RETURN VALUE
       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.

ERRORS
       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.

EXAMPLES
       None.

APPLICATION USAGE
       None.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       Scheduling Policies, sched__getparam(), sched__getscheduler(),
       sched__setscheduler()

       The Base Definitions volume of POSIX.1-2017, <sched.h>

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 .

       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(3)
