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34 .\" @(#)getpriority.2 8.1 (Berkeley) 6/4/93
42 .Nd get/set program scheduling priority
44 .Fd #include <sys/resource.h>
57 The scheduling priority of the process, process group, or user as indicated by
74 is interpreted relative to
76 (a process identifier for
85 denotes the current process, process group, or user.
87 is a value in the range -20 to 20. The default priority is 0;
88 lower priorities cause more favorable scheduling.
92 call returns the highest priority (lowest numerical value)
93 enjoyed by any of the specified processes.
96 call sets the priorities of all of the specified processes
97 to the specified value. Only the super-user may lower priorities.
99 Additionally, the current thread or process can be placed in a background state
100 by specifying PRIO_DARWIN_THREAD or PRIO_DARWIN_PROCESS for
102 Only a value of zero (the current thread or process) is supported for
104 when setting or getting background state.
106 is either 0 (to remove current thread from background status) or PRIO_DARWIN_BG
107 (to set current thread into background state).
108 When a thread or process is in a background state the scheduling priority is set
109 to the lowest value, disk IO is throttled (with behavior similar to using
111 to set a throttleable policy), and network IO is throttled for
112 any sockets opened after going into background state. Any previously opened
113 sockets are not affected.
116 call returns 0 when current thread or process is not in background state or 1
117 when the current thread is in background state. Any thread or process can set
118 itself into background state.
122 can legitimately return the value -1, it is necessary
123 to clear the external variable
126 call, then check it afterward to determine
127 if a -1 is an error or a legitimate value.
130 call returns 0 if there is no error, or
145 .Dv PRIO_DARWIN_THREAD ,
147 .Dv PRIO_DARWIN_PROCESS .
151 is not a valid process, process group, or user ID.
158 .Dv PRIO_DARWIN_THREAD
160 .Dv PRIO_DARWIN_PROCESS .
163 No process can be located using the
171 In addition to the errors indicated above,
176 A non super-user attempts to lower a process priority.
179 A process is located,
180 but neither its effective nor real user ID
181 matches the effective user ID of the caller.
184 .Fd #include <sys/types.h>
185 .Fd #include <sys/resource.h>
212 .Xr setiopolicy_np 3 ,
218 function call appeared in