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39 .Nd set and get a LWP's CPU affinity mask
45 .Fn lwp_setaffinity "pid_t pid" "lwpid_t tid" "const cpumask_t *mask"
47 .Fn lwp_getaffinity "pid_t pid" "lwpid_t tid" "cpumask_t *mask"
51 system call sets the CPU affinity mask of the LWP,
52 which is identified by the
56 to the value specified by the
61 then the pid of the calling process is used.
65 then all LWPs of the process identified by the
68 If the LWP specified by the
72 is the current LWP it will be migrated immediately,
73 if necessary, otherwise it will be migrated by the scheduler later.
80 inherits the calling LWP's CPU affinity mask.
81 Same applies to the LWPs created by
83 and the threads created by
84 .Xr pthread_create 3 .
87 writes the affinity mask of the LWP,
88 which is identified by the
92 to the cpumask_t structure pointed to by
97 then the pid of the calling process is used.
101 then the first LWP of specified process is used.
103 These system calls return \-1 on error and
104 0 upon successful completion.
110 system calls will fail if:
115 parameter is outside the process's allocated address space.
119 parameter is negative.
121 The LWP identified by the
129 does not contain a valid CPU.
135 .Xr sched_getaffinity 2 ,
136 .Xr sched_setaffinity 2 ,
138 .Xr pthread_create 3 ,
139 .Xr pthread_getaffinity_np 3 ,
140 .Xr pthread_setaffinity_np 3
146 functions first appeared in