| [860] | 1 | '\" t
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| 2 | .\" Title: vfs_readahead
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| 3 | .\" Author: [see the "AUTHOR" section]
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| [988] | 4 | .\" Generator: DocBook XSL Stylesheets v1.78.1 <http://docbook.sf.net/>
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| [989] | 5 | .\" Date: 10/25/2016
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| [860] | 6 | .\" Manual: System Administration tools
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| [988] | 7 | .\" Source: Samba 4.4
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| [860] | 8 | .\" Language: English
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| 9 | .\"
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| [989] | 10 | .TH "VFS_READAHEAD" "8" "10/25/2016" "Samba 4\&.4" "System Administration tools"
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| [860] | 11 | .\" -----------------------------------------------------------------
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| 12 | .\" * Define some portability stuff
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| 13 | .\" -----------------------------------------------------------------
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| 14 | .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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| 15 | .\" http://bugs.debian.org/507673
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| 16 | .\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
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| 21 | .\" * set default formatting
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| 27 | .\" -----------------------------------------------------------------
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| 28 | .\" * MAIN CONTENT STARTS HERE *
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| 29 | .\" -----------------------------------------------------------------
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| 30 | .SH "NAME"
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| 31 | vfs_readahead \- pre\-load the kernel buffer cache
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| 32 | .SH "SYNOPSIS"
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| 33 | .HP \w'\ 'u
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| 34 | vfs objects = readahead
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| 35 | .SH "DESCRIPTION"
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| 36 | .PP
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| 37 | This VFS module is part of the
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| 38 | \fBsamba\fR(7)
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| 39 | suite\&.
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| 40 | .PP
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| 41 | This
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| 42 | vfs_readahead
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| 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\&.
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| 44 | .PP
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| 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\&.
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| 46 | .PP
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| 47 | The offset multiple used is given by the readahead:offset option, which defaults to 0x80000\&.
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| 48 | .PP
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| 49 | The size of the disk read operations performed by
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| 50 | vfs_readahead
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| 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\&.
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| 52 | .PP
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| 53 | This module is stackable\&.
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