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PTHREAD_AFFINITY_NP(3) FreeBSD Library Functions Manual PTHREAD_AFFINITY_NP(3) NAME pthread_getaffinity_np, pthread_setaffinity_np -- manage CPU affinity LIBRARY POSIX Threads Library (libpthread, -lpthread) SYNOPSIS #include <pthread_np.h> int pthread_getaffinity_np(pthread_t td, size_t cpusetsize, cpuset_t *cpusetp); int pthread_setaffinity_np(pthread_t td, size_t cpusetsize, const cpuset_t *cpusetp); DESCRIPTION pthread_getaffinity_np() and pthread_setaffinity_np() allow the manipula- tion of sets of CPUs available to the specified thread. Masks of type cpuset_t are composed using the CPU_SET macros. The kernel tolerates large sets as long as all CPUs specified in the set exist. Sets smaller than the kernel uses generate an error on calls to pthread_getaffinity_np() even if the result set would fit within the user supplied set. Calls to pthread_setaffinity_np() tolerate small sets with no restrictions. The supplied mask should have a size of cpusetsize bytes. This size is usually provided by calling sizeof(cpuset_t) which is ultimately deter- mined by the value of CPU_SETSIZE as defined in <sys/cpuset.h>. pthread_getaffinity_np() retrieves the mask from the thread specified by td, and stores it in the space provided by cpusetp. pthread_setaffinity_np() attempts to set the mask for the thread speci- fied by td to the value in cpusetp. RETURN VALUES If successful, the pthread_getaffinity_np() and pthread_setaffinity_np() functions will return zero. Otherwise an error number will be returned to indicate the error. ERRORS The pthread_getaffinity_np() and pthread_setaffinity_np() functions may fail if: [EDEADLK] The pthread_setaffinity_np() call would leave a thread without a valid CPU to run on because the set does not overlap with the thread's anonymous mask. [EFAULT] The cpusetp pointer passed was invalid. [ESRCH] The thread specified by the td argument could not be found. [ERANGE] The cpusetsize was either preposterously large or smaller than the kernel set size. [EPERM] The calling thread did not have the credentials re- quired to complete the operation. SEE ALSO cpuset(1), cpuset(2), cpuset_getid(2), cpuset_setid(2), pthread(3), pthread_attr_getaffinity_np(3), pthread_attr_setaffinity_np(3) STANDARDS The pthread_getaffinity_np and pthread_setaffinity_np functions are non- standard FreeBSD extensions and may be not available on other operating systems. HISTORY The pthread_getaffinity_np and pthread_setaffinity_np function first ap- peared in FreeBSD 7.2. AUTHORS The pthread_getaffinity_np and pthread_setaffinity_np functions were written by David Xu <davidxu@FreeBSD.org>, and this manpage was written by Xin LI <delphij@FreeBSD.org>. FreeBSD 13.0 March 23, 2010 FreeBSD 13.0
NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | STANDARDS | HISTORY | AUTHORS
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