| 1 | '\" t
|
|---|
| 2 | .\" Title: vfs_readahead
|
|---|
| 3 | .\" Author: [see the "AUTHOR" section]
|
|---|
| 4 | .\" Generator: DocBook XSL Stylesheets v1.76.1 <http://docbook.sf.net/>
|
|---|
| 5 | .\" Date: 09/18/2013
|
|---|
| 6 | .\" Manual: System Administration tools
|
|---|
| 7 | .\" Source: Samba 3.6
|
|---|
| 8 | .\" Language: English
|
|---|
| 9 | .\"
|
|---|
| 10 | .TH "VFS_READAHEAD" "8" "09/18/2013" "Samba 3\&.6" "System Administration tools"
|
|---|
| 11 | .\" -----------------------------------------------------------------
|
|---|
| 12 | .\" * Define some portability stuff
|
|---|
| 13 | .\" -----------------------------------------------------------------
|
|---|
| 14 | .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|---|
| 15 | .\" http://bugs.debian.org/507673
|
|---|
| 16 | .\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
|
|---|
| 17 | .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|---|
| 18 | .ie \n(.g .ds Aq \(aq
|
|---|
| 19 | .el .ds Aq '
|
|---|
| 20 | .\" -----------------------------------------------------------------
|
|---|
| 21 | .\" * set default formatting
|
|---|
| 22 | .\" -----------------------------------------------------------------
|
|---|
| 23 | .\" disable hyphenation
|
|---|
| 24 | .nh
|
|---|
| 25 | .\" disable justification (adjust text to left margin only)
|
|---|
| 26 | .ad l
|
|---|
| 27 | .\" -----------------------------------------------------------------
|
|---|
| 28 | .\" * MAIN CONTENT STARTS HERE *
|
|---|
| 29 | .\" -----------------------------------------------------------------
|
|---|
| 30 | .SH "NAME"
|
|---|
| 31 | vfs_readahead \- pre\-load the kernel buffer cache
|
|---|
| 32 | .SH "SYNOPSIS"
|
|---|
| 33 | .HP \w'\ 'u
|
|---|
| 34 | vfs objects = readahead
|
|---|
| 35 | .SH "DESCRIPTION"
|
|---|
| 36 | .PP
|
|---|
| 37 | This VFS module is part of the
|
|---|
| 38 | \fBsamba\fR(7)
|
|---|
| 39 | suite\&.
|
|---|
| 40 | .PP
|
|---|
| 41 | This
|
|---|
| 42 | vfs_readahead
|
|---|
| 43 | VFS module detects read requests at multiples of a given offset (hex 0x80000 by default) and then tells the kernel via either the readahead system call (on Linux) or the posix_fadvise system call to pre\-fetch this data into the buffer cache\&.
|
|---|
| 44 | .PP
|
|---|
| 45 | This module is useful for Windows Vista clients reading data using the Windows Explorer program, which asynchronously does multiple file read requests at offset boundaries of 0x80000 bytes\&.
|
|---|
| 46 | .PP
|
|---|
| 47 | The offset multiple used is given by the readahead:offset option, which defaults to 0x80000\&.
|
|---|
| 48 | .PP
|
|---|
| 49 | The size of the disk read operations performed by
|
|---|
| 50 | vfs_readahead
|
|---|
| 51 | is determined by the readahead:length option\&. By default this is set to the same value as the readahead:offset option and if not set explicitly will use the current value of readahead:offset\&.
|
|---|
| 52 | .PP
|
|---|
| 53 | This module is stackable\&.
|
|---|
| 54 | .SH "OPTIONS"
|
|---|
| 55 | .PP
|
|---|
| 56 | readahead:offset = BYTES
|
|---|
| 57 | .RS 4
|
|---|
| 58 | The offset multiple that causes readahead to be requested of the kernel buffer cache\&.
|
|---|
| 59 | .RE
|
|---|
| 60 | .PP
|
|---|
| 61 | readahead:length = BYTES
|
|---|
| 62 | .RS 4
|
|---|
| 63 | The number of bytes requested to be read into the kernel buffer cache on each readahead call\&.
|
|---|
| 64 | .RE
|
|---|
| 65 | .PP
|
|---|
| 66 | The following suffixes may be applied to BYTES:
|
|---|
| 67 | .sp
|
|---|
| 68 | .RS 4
|
|---|
| 69 | .ie n \{\
|
|---|
| 70 | \h'-04'\(bu\h'+03'\c
|
|---|
| 71 | .\}
|
|---|
| 72 | .el \{\
|
|---|
| 73 | .sp -1
|
|---|
| 74 | .IP \(bu 2.3
|
|---|
| 75 | .\}
|
|---|
| 76 | K
|
|---|
| 77 | \- BYTES is a number of kilobytes
|
|---|
| 78 | .RE
|
|---|
| 79 | .sp
|
|---|
| 80 | .RS 4
|
|---|
| 81 | .ie n \{\
|
|---|
| 82 | \h'-04'\(bu\h'+03'\c
|
|---|
| 83 | .\}
|
|---|
| 84 | .el \{\
|
|---|
| 85 | .sp -1
|
|---|
| 86 | .IP \(bu 2.3
|
|---|
| 87 | .\}
|
|---|
| 88 | M
|
|---|
| 89 | \- BYTES is a number of megabytes
|
|---|
| 90 | .RE
|
|---|
| 91 | .sp
|
|---|
| 92 | .RS 4
|
|---|
| 93 | .ie n \{\
|
|---|
| 94 | \h'-04'\(bu\h'+03'\c
|
|---|
| 95 | .\}
|
|---|
| 96 | .el \{\
|
|---|
| 97 | .sp -1
|
|---|
| 98 | .IP \(bu 2.3
|
|---|
| 99 | .\}
|
|---|
| 100 | G
|
|---|
| 101 | \- BYTES is a number of gigabytes
|
|---|
| 102 | .RE
|
|---|
| 103 | .SH "EXAMPLES"
|
|---|
| 104 | .sp
|
|---|
| 105 | .if n \{\
|
|---|
| 106 | .RS 4
|
|---|
| 107 | .\}
|
|---|
| 108 | .nf
|
|---|
| 109 | \fI[hypothetical]\fR
|
|---|
| 110 | \m[blue]\fBvfs objects = readahead\fR\m[]
|
|---|
| 111 | .fi
|
|---|
| 112 | .if n \{\
|
|---|
| 113 | .RE
|
|---|
| 114 | .\}
|
|---|
| 115 | .SH "VERSION"
|
|---|
| 116 | .PP
|
|---|
| 117 | This man page is correct for version 3\&.0\&.25 of the Samba suite\&.
|
|---|
| 118 | .SH "AUTHOR"
|
|---|
| 119 | .PP
|
|---|
| 120 | The original Samba software and related utilities were created by Andrew Tridgell\&. Samba is now developed by the Samba Team as an Open Source project similar to the way the Linux kernel is developed\&.
|
|---|
