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AFFINITY(3) Library Functions Manual AFFINITY(3) NAME pthread_setaffinity_np, pthread_getaffinity_np -- affinity of threads LIBRARY POSIX Threads Library (libpthread, -lpthread) SYNOPSIS #include <pthread.h> #include <sched.h> int pthread_setaffinity_np(pthread_t thread, size_t size, cpuset_t *set); int pthread_getaffinity_np(pthread_t thread, size_t size, cpuset_t *set); DESCRIPTION Thread affinity allows to run the thread on specified CPU or CPUs only. The pthread_setaffinity_np() function sets the affinity mask set for thread. At least one valid CPU must be set in the mask. The pthread_getaffinity_np() function gets the affinity mask of thread into set. Note that set must be created and initialized using the cpuset(3) functions. IMPLEMENTATION NOTES Setting CPU pthread_setaffinity_np requires super-user privileges. Ordi- nary users can be allowed to control CPU affinity of their threads via the security.models.extensions.user_set_cpu_affinity sysctl(7). See sec- model_extensions(9). Portable applications should not use the pthread_setaffinity_np() and pthread_getaffinity_np() functions. RETURN VALUES The pthread_setaffinity_np() and pthread_getaffinity_np() functions return 0 on success. Otherwise, an error number is returned to indicate the er- ror. EXAMPLES An example of code fragment, which sets the affinity for the current thread to the CPU whose ID is 0: cpuset_t *cset; pthread_t pth; cpuid_t ci; cset = cpuset_create(); if (cset == NULL) { err(EXIT_FAILURE, "cpuset_create"); } ci = 0; cpuset_set(ci, cset); pth = pthread_self(); error = pthread_setaffinity_np(pth, cpuset_size(cset), cset); if (error) { ... } cpuset_destroy(cset); COMPATIBILITY Both functions are non-standard extensions. ERRORS Both functions may fail if: [EINVAL] The specified set was invalid. [EPERM] The calling process lacks the appropriate privileges to perform the operation. [ESRCH] No thread could be found corresponding to the one speci- fied by thread. NOTES There is an alternative processor sets interface, see pset(3). However, thread affinity and processor sets are mutually exclusive, hence mixing of these interfaces is prohibited. SEE ALSO cpuset(3), pset(3), pthread_getschedparam(3), pthread_setschedparam(3), sched(3), schedctl(8) NetBSD 9.0 December 4, 2011 AFFINITY(3)
NAME | LIBRARY | SYNOPSIS | DESCRIPTION | IMPLEMENTATION NOTES | RETURN VALUES | EXAMPLES | COMPATIBILITY | ERRORS | NOTES | SEE ALSO
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