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.Dd March 12, 1998 .Dt SCHED_SETSCHEDULER 2 .Os .Sh NAME .Nm sched_setscheduler , .Nm sched_getscheduler .Nd set/get scheduling policy and scheduler parameters .Sh LIBRARY .Lb libc .Sh SYNOPSIS n sched.h .Ft int .Fn sched_setscheduler "pid_t pid" "int policy" "const struct sched_param *param" .Ft int .Fn sched_getscheduler "pid_t pid" .Sh DESCRIPTION The .Fn sched_setscheduler system call sets the scheduling policy and scheduling parameters of the process specified by .Fa pid to .Fa policy and the parameters specified in the .Vt sched_param structure pointed to by .Fa param , respectively. The value of the .Fa sched_priority member in the .Fa param structure must be any integer within the inclusive priority range for the scheduling policy specified by .Fa policy .
p In this implementation, if the value of .Fa pid is negative the system call will fail.
p If a process specified by .Fa pid exists and if the calling process has permission, the scheduling policy and scheduling parameters will be set for the process whose process ID is equal to .Fa pid .
p If .Fa pid is zero, the scheduling policy and scheduling parameters are set for the calling process.
p In this implementation, the policy of when a process can affect the scheduling parameters of another process is specified in .St -p1003.1b-93 as a write-style operation.
p The scheduling policies are in .Fa <sched.h> : l -tag -width [SCHED_OTHER] t Bq Er SCHED_FIFO First-in-first-out fixed priority scheduling with no round robin scheduling; t Bq Er SCHED_OTHER The standard time sharing scheduler; t Bq Er SCHED_RR Round-robin scheduling across same priority processes. .El
p The .Vt sched_param structure is defined in .Fa <sched.h> : d -literal -offset indent struct sched_param { int sched_priority; /* scheduling priority */ }; .Ed
p The .Fn sched_getscheduler system call returns the scheduling policy of the process specified by .Fa pid .
p If a process specified by .Fa pid exists and if the calling process has permission, the scheduling parameters for the process whose process ID is equal to .Fa pid are returned.
p In this implementation, the policy of when a process can obtain the scheduling parameters of another process are detailed in .St -p1003.1b-93 as a read-style operation.
p If .Fa pid is zero, the scheduling parameters for the calling process will be returned. In this implementation, the .Fa sched_getscheduler system call will fail if .Fa pid is negative. .Sh RETURN VALUES .Rv -std .Sh ERRORS On failure .Va errno will be set to the corresponding value: l -tag -width Er t Bq Er ENOSYS The system is not configured to support this functionality. t Bq Er EPERM The requesting process doesn not have permission as detailed in .St -p1003.1b-93 . t Bq Er ESRCH No process can be found corresponding to that specified by .Fa pid . t Bq Er EINVAL The value of the .Fa policy argument is invalid, or one or more of the parameters contained in .Fa param is outside the valid range for the specified scheduling policy. .El .Sh SEE ALSO .Xr sched_get_priority_max 2 , .Xr sched_get_priority_min 2 , .Xr sched_getparam 2 , .Xr sched_rr_get_interval 2 , .Xr sched_setparam 2 , .Xr sched_yield 2 .Sh STANDARDS The .Fn sched_setscheduler and .Fn sched_getscheduler system calls conform to .St -p1003.1b-93 .