1.\" 2.\" Copyright (c) 2010 The DragonFly Project. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in 12.\" the documentation and/or other materials provided with the 13.\" distribution. 14.\" 3. Neither the name of The DragonFly Project nor the names of its 15.\" contributors may be used to endorse or promote products derived 16.\" from this software without specific, prior written permission. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 19.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 20.\" LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 21.\" FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 22.\" COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 23.\" INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 24.\" BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 25.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 26.\" AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 27.\" OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 28.\" OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.Dd May 12, 2010 32.Dt IOPRIO_GET 2 33.Os 34.Sh NAME 35.Nm ioprio_get , 36.Nm ioprio_set 37.Nd get/set the I/O priority 38.Sh LIBRARY 39.Lb libc 40.Sh SYNOPSIS 41.In sys/resource.h 42.Ft int 43.Fn ioprio_get "int which" "int who" 44.Ft int 45.Fn ioprio_set "int which" "int who" "int prio" 46.Sh DESCRIPTION 47The 48.Fn ioprio_get 49and 50.Fn ioprio_set 51functions get and set the I/O scheduler priority of a process, process group 52or all processes of a user. 53.Pp 54The 55.Fa which 56argument specifies what type of resource's priority is to be modified. 57It can have the following values (as defined in 58.In sys/resource.h ) : 59.Bl -tag -width ".Dv PRIO_PROCESS" 60.It Dv PRIO_PROCESS 61A single process 62.It Dv PRIO_PGRP 63A process group 64.It Dv PRIO_USER 65All processes of a user 66.El 67.Pp 68The 69.Fa who 70argument specifies, depending on the 71.Fa which 72argument, either the process ID (if 73.Fa which 74is 75.Dv PRIO_PROCESS ) , 76the process group ID (if 77.Fa which 78is 79.Dv PRIO_PGRP ) , 80or the user ID (if 81.Fa which 82is 83.Dv PRIO_USER ) . 84A value of 0 specifies either the current process, the current process group, 85or the current user. 86.Pp 87For the 88.Fn ioprio_set 89function, the 90.Fa prio 91argument specifies the priority to be set. 92It can range from 1 to 10, with higher numbers indicating a higher priority. 93.Sh RETURN VALUES 94.Rv -std ioprio_get ioprio_set 95.Sh ERRORS 96The 97.Fn ioprio_get 98function will fail if: 99.Bl -tag -width ".Bq Er EINVAL" 100.It Bq Er EINVAL 101An invalid value was specified for the 102.Fa which 103argument 104.It Bq Er ESRCH 105No corresponding process, process group or user could be found for the ID 106specified in 107.Fa who 108.El 109.Pp 110The 111.Fn ioprio_set 112function will fail if: 113.Bl -tag -width ".Bq Er EACCES" 114.It Bq Er EACCES 115The caller isn't allowed to access the I/O priority 116.It Bq Er EINVAL 117An invalid value was specified for the 118.Fa which 119argument 120.It Bq Er EPERM 121The caller doesn't own the specified process or processes 122.It Bq Er ESRCH 123No corresponding process, process group or user could be found for the ID 124specified in 125.Fa who 126.El 127.Sh SEE ALSO 128.Xr ioprio 1 129.Sh HISTORY 130The 131.Fn ioprio_get 132and 133.Fn ioprio_set 134function calls first appeared in 135.Dx 2.7 . 136.Sh AUTHORS 137.An -nosplit 138.An Alex Hornung 139