PROLOG         top

       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         top

       sched_setscheduler — set scheduling policy and parameters (REALTIME)

SYNOPSIS         top

       #include <sched.h>

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

DESCRIPTION         top

       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

       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.

RETURN VALUE         top

       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

ERRORS         top

       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

       The following sections are informative.

EXAMPLES         top




RATIONALE         top




SEE ALSO         top

       Scheduling Policies, sched_getparam(3p), sched_getscheduler(3p),

       The Base Definitions volume of POSIX.1‐2008, sched.h(0p)

COPYRIGHT         top

       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 .

       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 .

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)