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All Rights Reserved. .\" .TH SCHED_SETSCHEDULER 3C "Nov 26, 2017" .SH NAME sched_setscheduler \- set scheduling policy and scheduling parameters .SH SYNOPSIS .LP .nf #include \fBint\fR \fBsched_setscheduler\fR(\fBpid_t\fR \fIpid\fR, \fBint\fR \fIpolicy\fR, \fBconst struct sched_param *\fR\fIparam\fR); .fi .SH DESCRIPTION .LP The \fBsched_setscheduler()\fR function sets the scheduling policy and scheduling parameters of the process specified by \fIpid\fR to \fIpolicy\fR and the parameters specified in the \fBsched_param\fR structure pointed to by \fIparam\fR, respectively. The value of the \fBsched_priority\fR member in the \fBsched_param\fR structure is any integer within the inclusive priority range for the scheduling policy specified by \fIpolicy\fR. The \fBsched_setscheduler()\fR function ignores the other members of the \fBsched_param\fR structure. If the value of \fIpid\fR is negative, the behavior of the \fBsched_setscheduler()\fR function is unspecified. .sp .LP The possible values for the \fIpolicy\fR parameter are defined in the header <\fBsched.h\fR> (see \fBsched.h\fR(3HEAD)): .sp .LP If a process specified by \fIpid\fR exists and if the calling process has permission, the scheduling policy and scheduling parameters are set for the process whose process \fBID\fR is equal to \fIpid.\fR The real or effective user \fBID\fR of the calling process must match the real or saved (from \fBexec\fR(2)) user \fBID\fR of the target process unless the effective user \fBID\fR of the calling process is 0. See \fBIntro\fR(2). .sp .LP If \fIpid\fR is 0, the scheduling policy and scheduling parameters are set for the calling process. .sp .LP To change the \fIpolicy\fR of any process to either of the real time policies \fBSCHED_FIFO\fR or \fBSCHED_RR\fR, the calling process must either have the \fBSCHED_FIFO\fR or \fBSCHED_RR\fR policy or have an effective user \fBID\fR of \fB0\fR. .sp .LP The \fBsched_setscheduler()\fR function is considered successful if it succeeds in setting the scheduling policy and scheduling parameters of the process specified by \fIpid\fR to the values specified by \fIpolicy\fR and the structure pointed to by \fIparam\fR, respectively. .SH RETURN VALUES .LP Upon successful completion, the function returns the former scheduling policy of the specified process. If the \fBsched_setscheduler()\fR function fails to complete successfully, the policy and scheduling parameters remain unchanged, and the function returns \(mi1 and sets \fBerrno\fR to indicate the error. .SH ERRORS .LP The \fBsched_setscheduler()\fR function will fail if: .sp .ne 2 .na \fB\fBEINVAL\fR\fR .ad .RS 10n The value of \fIpolicy\fR is invalid, or one or more of the parameters contained in \fIparam\fR is outside the valid range for the specified scheduling policy. .RE .sp .ne 2 .na \fB\fBEPERM\fR\fR .ad .RS 10n The requesting process does not have permission to set either or both of the scheduling parameters or the scheduling policy of the specified process. .RE .sp .ne 2 .na \fB\fBESRCH\fR\fR .ad .RS 10n No process can be found corresponding to that specified by \fIpid.\fR .RE .SH ATTRIBUTES .LP See \fBattributes\fR(5) for descriptions of the following attributes: .sp .sp .TS box; c | c l | l . ATTRIBUTE TYPE ATTRIBUTE VALUE _ Interface Stability Committed _ MT-Level MT-Safe _ Standard See \fBstandards\fR(5). .TE .SH SEE ALSO .LP \fBpriocntl\fR(1), \fBIntro\fR(2), \fBexec\fR(2), \fBpriocntl\fR(2), \fBlibrt\fR(3LIB), \fBsched.h\fR(3HEAD), \fBsched_get_priority_max\fR(3C), \fBsched_getparam\fR(3C), \fBsched_getscheduler\fR(3C), \fBsched_setparam\fR(3C), \fBattributes\fR(5), \fBstandards\fR(5)