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 SCHED_SETAFFINITY 2 35.Os 36.Sh NAME 37.Nm CPU_AND , 38.Nm CPU_CLR , 39.Nm CPU_COUNT , 40.Nm CPU_EQUAL , 41.Nm CPU_ISSET , 42.Nm CPU_OR , 43.Nm CPU_SET , 44.Nm CPU_XOR , 45.Nm CPU_ZERO , 46.Nm sched_setaffinity , 47.Nm sched_getaffinity 48.Nd set and get a process's CPU affinity mask 49.Sh LIBRARY 50.Lb libc 51.Sh SYNOPSIS 52.In sys/types.h 53.In sys/sched.h 54.Ft int 55.Fn sched_setaffinity "pid_t pid" "size_t cpusetsize" "const cpu_set_t *mask" 56.Ft int 57.Fn sched_getaffinity "pid_t pid" "size_t cpusetsize" "cpu_set_t *mask" 58.Fn CPU_ZERO &mask 59.Fn CPU_SET cpu &mask 60.Fn CPU_CLR cpu &mask 61.Fn CPU_ISSET cpu &mask 62.Fn CPU_COUNT &mask 63.Fn CPU_AND &dstmask &srcmask1 &srcmask2 64.Fn CPU_OR &dstmask &srcmask1 srcmask2 65.Fn CPU_XOR &dstmask &srcmask1 &srcmask2 66.Fn CPU_EQUAL &mask1 &mask2 67.Sh DESCRIPTION 68.Pp 69The 70.Fn sched_setaffinity 71sets the CPU affinity mask of the process, 72which is identified by the 73.Fa pid 74to the value specified by the 75.Fa mask . 76The 77.Fa cpusetsize 78is the length (in bytes) of the data pointed to by 79.Fa mask . 80Normally this argument would be specified as sizeof(cpu_set_t). 81If the 82.Fa pid 83is zero, 84then the pid of the calling process is used. 85All threads of the process identified by 86.Fa pid 87are affected. 88If the calling thread is one of the target process's threads, 89then the calling thread will be migrated immediately, 90if necessary, 91while other threads of the targt process will be migrated 92by the scheduler later. 93.Pp 94A process created by 95.Xr fork 2 , 96.Xr vfork 2 , 97and 98.Xr rfork 2 99inherits the calling thread's CPU affinity mask. 100Same applies to the threads created by 101.Xr lwp_create 2 , 102and the threads created by 103.Xr pthread_create 3 . 104.Pp 105.Fn sched_getaffinity 106writes the affinity mask of the process 107identified by the 108.Fa pid 109to the cpu_set_t structure pointed to by 110.Fa mask . 111If the 112.Fa pid 113is zero, 114then the pid of the calling process is used. 115If the process is multithreaded, 116then the CPU affinity mask of the first thread will be returned. 117.Pp 118The cpu_set_t data structure represents a set of CPUs. 119The first available CPU on the system corresponds to a cpu value of 0, 120the next CPU corresponds to a cpu value of 1, 121and so on and so forth. 122The constant 123.Dv CPU_SETSIZE 124specifies a value one greater than the maximum 125CPU number that can be stored in cpu_set_t. 126The cpu_set_t should be treated as opaque data structure; 127all manipulation of cpu_set_t should be done via the following macros: 128.Bl -tag -width "CPU_COUNTxxx" 129.It Fn CPU_ZERO 130Reset the 131.Fa mask , 132so that it contains no CPUs. 133.It Fn CPU_SET 134Add the 135.Fa cpu 136to the 137.Fa mask . 138.It Fn CPU_CLR 139Remove the 140.Fa cpu 141from the 142.Fa mask . 143.It Fn CPU_ISSET 144Test to see whether the 145.Fa cpu 146is a member of the 147.Fa mask . 148.It Fn CPU_COUNT 149Return the number of CPUs in the 150.Fa mask . 151.It Fn CPU_AND 152Store the intersection of the 153.Fa srcmask1 154and the 155.Fa srcmask2 156in the 157.Fa dstmask . 158The 159.Fa dstmask 160could be one of the source masks. 161.It Fn CPU_OR 162Store the union of the 163.Fa srcmask1 164and the 165.Fa srcmask2 166in the 167.Fa dstmask . 168The 169.Fa dstmask 170could be one of the source masks. 171.It Fn CPU_XOR 172Store the XOR of the 173.Fa srcmask1 174and the 175.Fa srcmask2 176in the 177.Fa dstmask . 178The 179.Fa dstmask 180could be one of the source masks. 181.It Fn CPU_EQUAL 182Test whether the 183.Fa mask1 184and the 185.Fa mask2 186contain the same CPUs. 187.El 188.Sh RETURN VALUES 189These system calls return \-1 on error and 1900 upon successful completion. 191.Sh ERRORS 192The 193.Fn sched_setaffinity 194and 195.Fn sched_getaffinity 196will fail if: 197.Bl -tag -width Er 198.It Bq Er EFAULT 199The 200.Fa mask 201parameter is outside the process's allocated address space. 202.It Bq Er EINVAL 203The 204.Fa pid 205parameter is negative. 206.It Bq Er ESRCH 207The process identified by the 208.Fa pid 209does not exist. 210.It Bq Er EPERM 211The 212.Fa mask 213does not contain a valid CPU. 214.El 215.Sh SEE ALSO 216.Xr fork 2 217.Xr lwp_create 2 218.Xr lwp_getaffinity 2 219.Xr lwp_setaffinity 2 220.Xr pthread_create 3 221.Xr pthread_getaffinity_np 3 222.Xr pthread_setaffinity_np 3 223.Xr rfork 2 224.Xr vfork 2 225.Sh HISTORY 226The 227.Fn sched_setaffinity 228and 229.Fn sched_getaffinity 230functions first appeared in 231.Dx 4.7 . 232