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 2 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 50.Pp 51The 52.Fn pthread_setaffinity_np 53sets the CPU affinity mask of the thread identified by 54.Fa tid 55to the value specified by the 56.Fa mask . 57The 58.Fa cpusetsize 59is the length (in bytes) of the data pointed to by 60.Fa mask . 61Normally this argument would be specified as sizeof(cpu_set_t). 62If the thread specified by the 63.Fa tid 64is the current thread, 65it will be migrated immediately, 66if necessary, otherwise it will be migrated by the scheduler later. 67.Pp 68A process created by 69.Xr fork 2 , 70.Xr vfork 2 , 71and 72.Xr rfork 2 73inherits the calling thread's CPU affinity mask. 74Same applies to the threads created by 75.Xr lwp_create 2 , 76and the threads created by 77.Xr pthread_create 3 . 78.Pp 79.Fn pthread_getaffinity_np 80writes the affinity mask of the thread 81identified by the 82.Fa tid 83to the cpu_set_t structure pointed to by 84.Fa mask . 85.Pp 86The cpu_set_t data structure represents a set of CPUs. 87See 88.Xr sched_setaffinity 2 89for details. 90.Sh RETURN VALUES 91If successful, 92these functions will return zero. 93Otherwise an error number will be returned to indicate the error. 94.Sh ERRORS 95The 96.Fn pthread_setaffinity_np 97and 98.Fn pthread_getaffinity_np 99will fail if: 100.Bl -tag -width Er 101.It Bq Er EFAULT 102The 103.Fa mask 104parameter is outside the process's allocated address space. 105.It Bq Er EINVAL 106The 107.Fa tid 108parameter is invalid. 109.It Bq Er ESRCH 110The thread identified by the 111.Fa tid 112does not exist. 113.It Bq Er EPERM 114The 115.Fa mask 116does not contain a valid CPU. 117.El 118.Sh SEE ALSO 119.Xr fork 2 120.Xr lwp_create 2 121.Xr lwp_getaffinity 2 122.Xr lwp_setaffinity 2 123.Xr pthread_create 3 124.Xr rfork 2 125.Xr sched_getaffinity 2 126.Xr sched_setaffinity 2 127.Xr vfork 2 128.Sh HISTORY 129The 130.Fn pthread_setaffinity_np 131and 132.Fn pthread_getaffinity_np 133functions first appeared in 134.Dx 4.7 . 135