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All Rights Reserved. .\" .TH SCHED_SETPARAM 3C "Apr 1, 2008" .SH NAME sched_setparam \- set scheduling parameters .SH SYNOPSIS .LP .nf #include \fBint\fR \fBsched_setparam\fR(\fBpid_t\fR \fIpid\fR, \fBconst struct sched_param *\fR\fIparam\fR); .fi .SH DESCRIPTION .sp .LP The \fBsched_setparam()\fR function sets the scheduling parameters of the process specified by \fIpid\fR to the values specified by the \fBsched_param\fR structure pointed to by \fIparam\fR. The value of the \fIsched_priority\fR member in the \fBsched_param\fR structure is any integer within the inclusive priority range for the current scheduling policy of the process specified by \fIpid\fR. Higher numerical values for the priority represent higher priorities. If the value of \fIpid\fR is negative, the behavior of the \fBsched_setparam()\fR function is unspecified. .sp .LP If a process specified by \fIpid\fR exists and if the calling process has permission, the scheduling parameters will be 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 \fB0\fR. See \fBIntro\fR(2). .sp .LP If \fIpid\fR is zero, the scheduling parameters will be set for the calling process. .sp .LP The target process, whether it is running or not running, resumes execution after all other runnable processes of equal or greater priority have been scheduled to run. .sp .LP If the priority of the process specified by the \fIpid\fR argument is set higher than that of the lowest priority running process and if the specified process is ready to run, the process specified by the \fIpid\fR argument preempts a lowest priority running process. Similarly, if the process calling \fBsched_setparam()\fR sets its own priority lower than that of one or more other non-empty process lists, then the process that is the head of the highest priority list also preempts the calling process. Thus, in either case, the originating process might not receive notification of the completion of the requested priority change until the higher priority process has executed. .SH RETURN VALUES .sp .LP If successful, the \fBsched_setparam()\fR function returns \fB0\fR. .sp .LP If the call to \fBsched_setparam()\fR is unsuccessful, the priority remains unchanged, and the function returns \fB\(mi1\fR and sets \fBerrno\fR to indicate the error. .SH ERRORS .sp .LP The \fBsched_setparam()\fR function will fail if: .sp .ne 2 .na \fB\fBEINVAL\fR\fR .ad .RS 10n One or more of the requested scheduling parameters is outside the range defined for the scheduling policy of the specified \fIpid\fR. .RE .sp .ne 2 .na \fB\fBEPERM\fR\fR .ad .RS 10n The requesting process does not have permission to set the scheduling parameters for the specified process, or does not have the appropriate privilege to invoke \fBsched_setparam()\fR. .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 .sp .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 .sp .LP \fBIntro\fR(2), \fBexec\fR(2), \fBlibrt\fR(3LIB), \fBsched.h\fR(3HEAD), \fBsched_getparam\fR(3C), \fBsched_getscheduler\fR(3C), \fBsched_setscheduler\fR(3C), \fBattributes\fR(5), \fBstandards\fR(5)