affinity(3) - NetBSD Manual Pages

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AFFINITY(3)             NetBSD Library Functions Manual            AFFINITY(3)

pthread_setaffinity_np, pthread_getaffinity_np -- affinity of threads
POSIX Threads Library (libpthread, -lpthread)
#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);
Thread affinity allows to run the thread on specified CPU or CPUs only. 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) func- tions.
The pthread_setaffinity_np() and pthread_getaffinity_np() functions return 0 on success. Otherwise, an error number is returned to indicate the error.
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);
The pthread_setaffinity_np() and pthread_getaffinity_np() functions 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 specified by thread.
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.
cpuset(3), pset(3), pthread_getschedparam(3), pthread_setschedparam(3), sched(3), schedctl(8) NetBSD 5.0 October 18, 2008 NetBSD 5.0
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