1.\" Copyright (c) 2003 Poul-Henning Kamp 2.\" 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.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. The names of the authors may not be used to endorse or promote 13.\" products derived from this software without specific prior written 14.\" permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" $FreeBSD$ 29.\" 30.Dd February 8, 2003 31.Dt LIBGEOM 3 32.Os 33.Sh NAME 34.Nm geom_stats_open , 35.Nm geom_stats_close , 36.Nm geom_stats_resync , 37.Nm geom_stats_snapshot_get , 38.Nm geom_stats_snapshot_free , 39.Nm geom_stats_snapshot_timestamp , 40.Nm geom_stats_snapshot_reset , 41.Nm geom_stats_snapshot_next 42.Nd userland API library for kernel GEOM subsystem 43.Sh LIBRARY 44.Lb libgeom 45.Sh SYNOPSIS 46.In libgeom.h 47.Ss "Statistics Functions" 48.Ft void 49.Fn geom_stats_close void 50.Ft int 51.Fn geom_stats_open void 52.Ft void 53.Fn geom_stats_resync void 54.Ft "void *" 55.Fn geom_stats_snapshot_get void 56.Ft void 57.Fn geom_stats_snapshot_free "void *arg" 58.Ft void 59.Fn geom_stats_snapshot_timestamp "void *arg" "struct timespec *tp" 60.Ft void 61.Fn geom_stats_snapshot_reset "void *arg" 62.Ft "struct g_stat *" 63.Fn geom_stats_snapshot_next "void *arg" 64.Sh DESCRIPTION 65The 66.Nm geom 67library contains the official and publicized API for 68interacting with the GEOM subsystem in the kernel. 69.Ss "Statistics Functions" 70GEOM collects statistics data for all consumers and providers, but does 71not perform any normalization or presentation on the raw data, this is 72left as an excercize for user-land presentation utilities. 73.Pp 74The 75.Fn geom_stats_open 76and 77.Fn geom_stats_close 78functions open and close the necessary pathways to access the raw 79statistics information in the kernel. 80These functions are likely to 81open one or more files and cache the file descriptors locally. 82.Fn geom_stats_open 83returns zero on success, and sets 84.Va errno 85if not. 86.Pp 87The 88.Fn geom_stats_resync 89function will check if more statistics collection points have been 90added in the kernel since 91.Fn geom_stats_open 92or the previous call to 93.Fn geom_stats_resync . 94.Pp 95The 96.Fn geom_stats_snapshot_get 97function 98will acquire a snapshot of the raw data from the kernel, and while a 99reasonable effort is made to make this snapshot as atomic and consistent 100as possible, no guarantee is given that it will actually be so. 101The snapshot must be freed again using the 102.Fn geom_stats_snapshot_free 103function. 104.Fn geom_stats_snapshot_get 105returns 106.Dv NULL 107on failure. 108.Pp 109The 110.Fn geom_stats_snapshot_timestamp 111function 112provides access to the timestamp acquired in the snapshot. 113.Pp 114The 115.Fn geom_stats_snapshot_reset 116and 117.Fn geom_stats_snapshot_next 118functions 119provide an iterator over the statistics slots in the snapshot. 120The 121.Fn geom_stats_snapshot_reset 122function 123forces the internal pointer in the snapshot back to before the first item. 124The 125.Fn geom_stats_snapshot_next 126function 127returns the next item, and 128.Dv NULL 129if there are no more items in the snapshot. 130.Sh AUTHORS 131.An Poul-Henning Kamp Aq phk@FreeBSD.org 132.Sh HISTORY 133The 134.Nm geom 135library appeared in 136.Fx 5.1 . 137