VFS_READAHEAD(8)VFS_READAHEAD(8)NAME
vfs_readahead - pre-load the kernel buffer cache
SYNOPSIS
vfs objects = readahead
DESCRIPTION
This VFS module is part of the samba(7) suite.
This vfs_readahead 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.
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.
The offset multiple used is given by the readahead:offset option, which defaults to 0x80000.
The size of the disk read operations performed by vfs_readahead 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.
This module is stackable.
OPTIONS
readahead:offset = BYTES
The offset multiple that causes readahead to be requested of the kernel buffer cache.
readahead:length = BYTES
The number of bytes requested to be read into the kernel buffer cache on each readahead call.
The following suffixes may be applied to BYTES:
o K - BYTES is a number of kilobytes
o M - BYTES is a number of megabytes
o G - BYTES is a number of gigabytes
EXAMPLES
[hypothetical]
vfs objects = readahead
VERSION
This man page is correct for version 3.0.25 of the Samba suite.
AUTHOR
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.
VFS_READAHEAD(8)
Check Out this Related Man Page
VFS_CACHEPRIME(8) System Administration tools VFS_CACHEPRIME(8)NAME
vfs_cacheprime - prime the kernel file data cache
SYNOPSIS
vfs objects = cacheprime
DESCRIPTION
This VFS module is part of the samba(7) suite.
The vfs_cacheprime VFS module reads chunks of file data near the range requested by clients in order to make sure the data is present in
the kernel file data cache at the time when it is actually requested by clients.
The size of the disk read operations performed by vfs_cacheprime is determined by the cacheprime:rsize option. All disk read operations are
aligned on boundaries that are a multiple of this size. Each range of the file data is primed at most once during the time the client has
the file open.
This module is stackable.
OPTIONS
cacheprime:rsize = BYTES
The number of bytes with which to prime the kernel data cache.
The following suffixes may be applied to BYTES:
o K - BYTES is a number of kilobytes
o M - BYTES is a number of megabytes
o G - BYTES is a number of gigabytes
EXAMPLES
For a hypothetical disk array, it is necessary to ensure that all read operations are of size 1 megabyte (1048576 bytes), and aligned on 1
megabyte boundaries:
[hypothetical]
vfs objects = cacheprime
cacheprime:rsize = 1M
CAVEATS
cacheprime is not a substitute for a general-purpose readahead mechanism. It is intended for use only in very specific environments where
disk operations must be aligned and sized to known values (as much as that is possible).
VERSION
This man page is correct for version 3.0.25 of the Samba suite.
AUTHOR
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.
Samba 4.0 06/17/2014 VFS_CACHEPRIME(8)
i have a serious doubht about the assignment of memory
in hp-ux system .
i read from somewhere that the page allocation in
hp-ux is not unified unlike compaq .
i wanted to know in hp-ux kernel ,once the pages are
assigned for the univarsal buffer cache... (2 Replies)
Hi expert,
I have log :
TOTAL-TIME : 2125264636
DATA-BYTES-DOWN : 3766111307032
DATA-BYTES-UP : 455032157567
DL = (3766111307032/2125264636)/1024 = 1.73
UL = (455032157567/2125264636)/1024 = 0.21
I want the result :
TOTAL = 1.94 ... (4 Replies)