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34 .Dt SCHED_SETAFFINITY 2
37 .Nm sched_setaffinity,
39 .Nd set and get a process's CPU affinity mask
46 .Fn sched_setaffinity "pid_t pid" "size_t cpusetsize" "const cpu_set_t *mask"
48 .Fn sched_getaffinity "pid_t pid" "size_t cpusetsize" "cpu_set_t *mask"
52 .Fn CPU_ISSET cpu &mask
54 .Fn CPU_AND &dstmask &srcmask1 &srcmask2
55 .Fn CPU_OR &dstmask &srcmask1 srcmask2
56 .Fn CPU_XOR &dstmask &srcmask1 &srcmask2
57 .Fn CPU_EQUAL &mask1 &mask2
62 sets the CPU affinity mask of the process,
63 which is identified by the
65 to the value specified by the
69 is the length (in bytes) of the data pointed to by
71 Normally this argument would be specified as sizeof(cpu_set_t).
75 then the pid of the calling process is used.
76 All threads of the process identified by
79 If the calling thread is one of the target process's threads,
80 then the calling thread will be migrated immediately,
82 while other threads of the targt process will be migrated
83 by the scheduler later.
90 inherits the calling thread's CPU affinity mask.
91 Same applies to the threads created by
93 and the threads created by
94 .Xr pthread_create 3 .
97 writes the affinity mask of the process
100 to the cpu_set_t structure pointed to by
105 then the pid of the calling process is used.
106 If the process is multithreaded,
107 then the CPU affinity mask of the first thread will be returned.
109 The cpu_set_t data structure represents a set of CPUs.
110 The first available CPU on the system corresponds to a cpu value of 0,
111 the next CPU corresponds to a cpu value of 1,
112 and so on and so forth.
115 specifies a value one greater than the maximum
116 CPU number that can be stored in cpu_set_t.
117 The cpu_set_t should be treated as opaque data structure;
118 all manipulation of cpu_set_t should be done via the following macros:
119 .Bl -tag -width "CPU_COUNTxxx"
123 so that it contains no CPUs.
135 Test to see whether the
140 Return the number of CPUs in the
143 Store the intersection of the
151 could be one of the source masks.
153 Store the union of the
161 could be one of the source masks.
171 could be one of the source masks.
177 contain the same CPUs.
180 These system calls return \-1 on error and
181 0 upon successful completion.
184 .Fn sched_setaffinity
186 .Fn sched_getaffinity
192 parameter is outside the process's allocated address space.
196 parameter is negative.
198 The process identified by the
204 does not contain a valid CPU.
209 .Xr lwp_getaffinity 2
210 .Xr lwp_setaffinity 2
216 .Fn sched_setaffinity
218 .Fn sched_getaffinity
219 functions first appeared in