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39 .Nd set and get a LWP's CPU affinity mask
46 .Fn lwp_setaffinity "pid_t pid" "lwpid_t tid" "const cpumask_t *mask"
48 .Fn lwp_getaffinity "pid_t pid" "lwpid_t tid" "cpumask_t *mask"
52 system call sets the CPU affinity mask of the LWP,
53 which is identified by the
57 to the value specified by the
62 then the pid of the calling process is used.
66 then all LWPs of the process identified by the
69 If the LWP specified by the
73 is the current LWP it will be migrated immediately,
74 if necessary, otherwise it will be migrated by the scheduler later.
81 inherits the calling LWP's CPU affinity mask.
82 Same applies to the LWPs created by
84 and the threads created by
85 .Xr pthread_create 3 .
88 writes the affinity mask of the LWP,
89 which is identified by the
93 to the cpumask_t structure pointed to by
98 then the pid of the calling process is used.
102 then the first LWP of specified process is used.
104 These system calls return \-1 on error and
105 0 upon successful completion.
111 system calls will fail if:
116 parameter is outside the process's allocated address space.
120 parameter is negative.
122 The LWP identified by the
130 does not contain a valid CPU.
136 .Xr pthread_getaffinity_np 3
137 .Xr pthread_setaffinity_np 3
139 .Xr sched_getaffinity 2
140 .Xr sched_setaffinity 2
147 functions first appeared in