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.

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 .