xref: /dflybsd-src/lib/libc/sys/sched_setparam.2 (revision 86d7f5d305c6adaa56ff4582ece9859d73106103)
186d7f5d3SJohn Marino.\" $FreeBSD: src/lib/libc/sys/sched_setparam.2,v 1.4.2.8 2001/12/14 18:34:01 ru Exp $
286d7f5d3SJohn Marino.\" $DragonFly: src/lib/libc/sys/sched_setparam.2,v 1.3 2006/04/08 07:23:35 swildner Exp $
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2786d7f5d3SJohn Marino.Dd March 12, 1998
2886d7f5d3SJohn Marino.Dt SCHED_SETPARAM 2
2986d7f5d3SJohn Marino.Os
3086d7f5d3SJohn Marino.Sh NAME
3186d7f5d3SJohn Marino.Nm sched_setparam ,
3286d7f5d3SJohn Marino.Nm sched_getparam
3386d7f5d3SJohn Marino.Nd set/get scheduling parameters
3486d7f5d3SJohn Marino.Sh LIBRARY
3586d7f5d3SJohn Marino.Lb libc
3686d7f5d3SJohn Marino.Sh SYNOPSIS
3786d7f5d3SJohn Marino.In sched.h
3886d7f5d3SJohn Marino.Ft int
3986d7f5d3SJohn Marino.Fn sched_setparam "pid_t pid" "const struct sched_param *param"
4086d7f5d3SJohn Marino.Ft int
4186d7f5d3SJohn Marino.Fn sched_getparam "pid_t pid" "struct sched_param *param"
4286d7f5d3SJohn Marino.Sh DESCRIPTION
4386d7f5d3SJohn MarinoThe
4486d7f5d3SJohn Marino.Fn sched_setparam
4586d7f5d3SJohn Marinofunction sets the scheduling parameters of the process specified by
4686d7f5d3SJohn Marino.Fa pid
4786d7f5d3SJohn Marinoto the values specified by the
4886d7f5d3SJohn Marino.Fa sched_param
4986d7f5d3SJohn Marinostructure pointed to by
5086d7f5d3SJohn Marino.Fa param .
5186d7f5d3SJohn MarinoThe value of the
5286d7f5d3SJohn Marino.Fa sched_priority
5386d7f5d3SJohn Marinomember in the
5486d7f5d3SJohn Marino.Fa param
5586d7f5d3SJohn Marinostructure must be any integer within the inclusive priority range for
5686d7f5d3SJohn Marinothe current scheduling policy of the process specified by
5786d7f5d3SJohn Marino.Fa pid .
5886d7f5d3SJohn MarinoHigher numerical values for the priority represent higher priorities.
5986d7f5d3SJohn Marino.Pp
6086d7f5d3SJohn MarinoIn this implementation, if the value of
6186d7f5d3SJohn Marino.Fa pid
6286d7f5d3SJohn Marinois negative the function will fail.
6386d7f5d3SJohn Marino.Pp
6486d7f5d3SJohn MarinoIf a process specified by
6586d7f5d3SJohn Marino.Fa pid
6686d7f5d3SJohn Marinoexists and if the calling process has permission, the scheduling
6786d7f5d3SJohn Marinoparameters are set for the process whose process ID is equal to
6886d7f5d3SJohn Marino.Fa pid .
6986d7f5d3SJohn Marino.Pp
7086d7f5d3SJohn MarinoIf
7186d7f5d3SJohn Marino.Fa pid
7286d7f5d3SJohn Marinois zero, the scheduling parameters are set for the calling process.
7386d7f5d3SJohn Marino.Pp
7486d7f5d3SJohn MarinoIn this implementation, the policy of when a process can affect
7586d7f5d3SJohn Marinothe scheduling parameters of another process is specified in
7686d7f5d3SJohn Marino.St -p1003.1b-93
7786d7f5d3SJohn Marinoas a write-style operation.
7886d7f5d3SJohn Marino.Pp
7986d7f5d3SJohn MarinoThe target process, whether it is running or not running, will resume
8086d7f5d3SJohn Marinoexecution after all other runnable processes of equal or greater
8186d7f5d3SJohn Marinopriority have been scheduled to run.
8286d7f5d3SJohn Marino.Pp
8386d7f5d3SJohn MarinoIf the priority of the process specified by the
8486d7f5d3SJohn Marino.Fa pid
8586d7f5d3SJohn Marinoargument is set higher than that of the lowest priority running process
8686d7f5d3SJohn Marinoand if the specified process is ready to run, the process specified by
8786d7f5d3SJohn Marinothe
8886d7f5d3SJohn Marino.Fa pid
8986d7f5d3SJohn Marinoargument will preempt a lowest priority running process.  Similarly, if
9086d7f5d3SJohn Marinothe process calling
9186d7f5d3SJohn Marino.Fn sched_setparam
9286d7f5d3SJohn Marinosets its own priority lower than that of one or more other nonempty
9386d7f5d3SJohn Marinoprocess lists, then the process that is the head of the highest priority
9486d7f5d3SJohn Marinolist will also preempt the calling process.  Thus, in either case, the
9586d7f5d3SJohn Marinooriginating process might not receive notification of the completion of
9686d7f5d3SJohn Marinothe requested priority change until the higher priority process has
9786d7f5d3SJohn Marinoexecuted.
9886d7f5d3SJohn Marino.Pp
9986d7f5d3SJohn MarinoIn this implementation, when the current scheduling policy for the
10086d7f5d3SJohn Marinoprocess specified by
10186d7f5d3SJohn Marino.Fa pid
10286d7f5d3SJohn Marinois normal timesharing (SCHED_OTHER, aka SCHED_NORMAL when not POSIX-source)
10386d7f5d3SJohn Marinoor the idle policy (SCHED_IDLE when not POSIX-source) then the behavior
10486d7f5d3SJohn Marinois as if the process had been running under SCHED_RR with a priority
10586d7f5d3SJohn Marinolower than any actual realtime priority.
10686d7f5d3SJohn Marino.Pp
10786d7f5d3SJohn MarinoThe
10886d7f5d3SJohn Marino.Fn sched_getparam
10986d7f5d3SJohn Marinofunction will return the scheduling parameters of a process specified
11086d7f5d3SJohn Marinoby
11186d7f5d3SJohn Marino.Fa pid
11286d7f5d3SJohn Marinoin the
11386d7f5d3SJohn Marino.Fa sched_param
11486d7f5d3SJohn Marinostructure pointed to by
11586d7f5d3SJohn Marino.Fa param .
11686d7f5d3SJohn Marino.Pp
11786d7f5d3SJohn MarinoIf a process specified by
11886d7f5d3SJohn Marino.Fa pid
11986d7f5d3SJohn Marinoexists and if the calling process has permission,
12086d7f5d3SJohn Marinothe scheduling parameters for the process whose process ID is equal to
12186d7f5d3SJohn Marino.Fa pid
12286d7f5d3SJohn Marinoare returned.
12386d7f5d3SJohn Marino.Pp
12486d7f5d3SJohn MarinoIn this implementation, the policy of when a process can obtain the
12586d7f5d3SJohn Marinoscheduling parameters of another process are detailed in
12686d7f5d3SJohn Marino.St -p1003.1b-93
12786d7f5d3SJohn Marinoas a read-style operation.
12886d7f5d3SJohn Marino.Pp
12986d7f5d3SJohn MarinoIf
13086d7f5d3SJohn Marino.Fa pid
13186d7f5d3SJohn Marinois zero, the scheduling parameters for the calling process will be
13286d7f5d3SJohn Marinoreturned.  In this implementation, the
13386d7f5d3SJohn Marino.Fa sched_getparam
13486d7f5d3SJohn Marinofunction will fail if
13586d7f5d3SJohn Marino.Fa pid
13686d7f5d3SJohn Marinois negative.
13786d7f5d3SJohn Marino.Sh RETURN VALUES
13886d7f5d3SJohn Marino.Rv -std
13986d7f5d3SJohn Marino.Sh ERRORS
14086d7f5d3SJohn MarinoOn failure
14186d7f5d3SJohn Marino.Va errno
14286d7f5d3SJohn Marinowill be set to the corresponding value:
14386d7f5d3SJohn Marino.Bl -tag -width Er
14486d7f5d3SJohn Marino.It Bq Er ENOSYS
14586d7f5d3SJohn MarinoThe system is not configured to support this functionality.
14686d7f5d3SJohn Marino.It Bq Er EPERM
14786d7f5d3SJohn MarinoThe requesting process doesn not have permission as detailed in
14886d7f5d3SJohn Marino.St -p1003.1b-93 .
14986d7f5d3SJohn Marino.It Bq Er ESRCH
15086d7f5d3SJohn MarinoNo process can be found corresponding to that specified by
15186d7f5d3SJohn Marino.Fa pid .
15286d7f5d3SJohn Marino.It Bq Er EINVAL
15386d7f5d3SJohn MarinoFor
15486d7f5d3SJohn Marino.Fn sched_setparam :
15586d7f5d3SJohn Marinoone or more of the requested scheduling parameters
15686d7f5d3SJohn Marinois outside the range defined for the scheduling policy of the specified
15786d7f5d3SJohn Marino.Fa pid .
15886d7f5d3SJohn Marino.El
15986d7f5d3SJohn Marino.Sh SEE ALSO
16086d7f5d3SJohn Marino.Xr sched_getscheduler 2 ,
16186d7f5d3SJohn Marino.Xr sched_get_priority_max 2 ,
16286d7f5d3SJohn Marino.Xr sched_get_priority_min 2 ,
16386d7f5d3SJohn Marino.Xr sched_rr_get_interval 2 ,
16486d7f5d3SJohn Marino.Xr sched_setscheduler 2 ,
16586d7f5d3SJohn Marino.Xr sched_yield 2
16686d7f5d3SJohn Marino.Sh STANDARDS
16786d7f5d3SJohn MarinoThe
16886d7f5d3SJohn Marino.Fn sched_setparam
16986d7f5d3SJohn Marinoand
17086d7f5d3SJohn Marino.Fn sched_getparam
17186d7f5d3SJohn Marinofunctions conform to
17286d7f5d3SJohn Marino.St -p1003.1b-93 .
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