1.\" Copyright (c) 2017 The DragonFly Project. All rights reserved. 2.\" 3.\" This code is derived from software contributed to The DragonFly Project 4.\" by Sepherosa Ziehau <sepherosa@gmail.com>. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in 14.\" the documentation and/or other materials provided with the 15.\" distribution. 16.\" 3. Neither the name of The DragonFly Project nor the names of its 17.\" contributors may be used to endorse or promote products derived 18.\" from this software without specific, prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 21.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 22.\" LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 23.\" FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 24.\" COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 25.\" INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 26.\" BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 27.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 28.\" AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 29.\" OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 30.\" OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31.\" SUCH DAMAGE. 32.\" 33.Dd January 14, 2017 34.Dt PTHREAD_SETAFFINITY_NP 3 35.Os 36.Sh NAME 37.Nm pthread_setaffinity_np , 38.Nm pthread_getaffinity_np 39.Nd set and get the thread's CPU affinity mask 40.Sh LIBRARY 41.Lb libpthread 42.Sh SYNOPSIS 43.In pthread.h 44.In pthread_np.h 45.Ft int 46.Fn pthread_setaffinity_np "pthread_t tid" "size_t cpusetsize" "const cpu_set_t *mask" 47.Ft int 48.Fn pthread_getaffinity_np "pthread_t tid" "size_t cpusetsize" "cpu_set_t *mask" 49.Sh DESCRIPTION 50The 51.Fn pthread_setaffinity_np 52sets the CPU affinity mask of the thread identified by 53.Fa tid 54to the value specified by the 55.Fa mask . 56The 57.Fa cpusetsize 58is the length (in bytes) of the data pointed to by 59.Fa mask . 60Normally this argument would be specified as sizeof(cpu_set_t). 61If the thread specified by the 62.Fa tid 63is the current thread, 64it will be migrated immediately, 65if necessary, otherwise it will be migrated by the scheduler later. 66.Pp 67A process created by 68.Xr fork 2 , 69.Xr vfork 2 , 70and 71.Xr rfork 2 72inherits the calling thread's CPU affinity mask. 73Same applies to the threads created by 74.Xr lwp_create 2 , 75and the threads created by 76.Xr pthread_create 3 . 77.Pp 78.Fn pthread_getaffinity_np 79writes the affinity mask of the thread 80identified by the 81.Fa tid 82to the cpu_set_t structure pointed to by 83.Fa mask . 84.Pp 85The cpu_set_t data structure represents a set of CPUs. 86See 87.Xr sched_setaffinity 2 88for details. 89.Sh RETURN VALUES 90If successful, 91these functions will return zero. 92Otherwise an error number will be returned to indicate the error. 93.Sh ERRORS 94The 95.Fn pthread_setaffinity_np 96and 97.Fn pthread_getaffinity_np 98will fail if: 99.Bl -tag -width Er 100.It Bq Er EFAULT 101The 102.Fa mask 103parameter is outside the process's allocated address space. 104.It Bq Er EINVAL 105The 106.Fa tid 107parameter is invalid. 108.It Bq Er ESRCH 109The thread identified by the 110.Fa tid 111does not exist. 112.It Bq Er EPERM 113The 114.Fa mask 115does not contain a valid CPU. 116.El 117.Sh SEE ALSO 118.Xr fork 2 , 119.Xr lwp_create 2 , 120.Xr lwp_getaffinity 2 , 121.Xr lwp_setaffinity 2 , 122.Xr rfork 2 , 123.Xr sched_getaffinity 2 , 124.Xr sched_setaffinity 2 , 125.Xr vfork 2 , 126.Xr pthread_create 3 127.Sh HISTORY 128The 129.Fn pthread_setaffinity_np 130and 131.Fn pthread_getaffinity_np 132functions first appeared in 133.Dx 4.7 . 134