09-17-2014
That depends on how you're doing your IO operations. How are your apps coded to do read and/or stream your files? Do you have control over your application IO? What filesystem(s) are you using for data?
Assuming you're streaming video files without much random searching, you should be using direct IO and bypassing the cache since it's extremely unlikely that the proper file data will be cached when you do any searching.
Direct IO will be faster and it won't fragment memory because you won't be using the page cache.
Caching of file data only helps when data can be held in memory long enough to allow multiple reads of the same data, or when write operations are small and/or slow enough to be effectively coalesced into a smaller number of write operations. Streaming or copying large files fits neither of those criteria.
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LEARN ABOUT CENTOS
vfs_cacheprime
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)