03-16-2009
Performance issue!
In my C program i am using very large file(approx 400MB) to read parts of it frequently. But due to large file the performance of the program goes down very badly. It shows very high I/O usage and I/O wait time.
My question is, What are the ways to optimize or tune I/O on linux or how i can get better performance when i have to read a large flat file?
I am using
Red Hat Enterprise Linux ES release 4 (Nahant Update 4)
2.6.9-42.EL, x86_64 GNU/Linux
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LEARN ABOUT DEBIAN
approx
APPROX(8) System Manager's Manual APPROX(8)
NAME
approx - proxy server for Debian archive files
SYNOPSIS
approx [OPTION]...
DESCRIPTION
approx responds to HTTP requests made by apt-get(8). It maintains a cache of Debian archive files that have been previously downloaded, so
that it can respond with a local copy when possible. If a file not in the cache is requested, approx will download it from a remote Debian
repository and deliver the contents to the client, simultaneously caching it for future use.
Over time, the approx server cache will grow to contain multiple, unneeded versions of Debian packages. The approx-gc(8) program removes
these from the cache.
OPTIONS
-c file, --config file
Specify an additional configuration file. May be used multiple times.
USAGE
approx is invoked by inetd(8).
EXAMPLES
Suppose that a client machine's /etc/apt/sources.list file contains the following lines:
deb http://apt:9999/debian testing main
deb http://apt:9999/security testing/updates main
deb-src http://apt:9999/debian unstable main
In this example, apt is the hostname of the approx server machine on the local network. Each distribution, such as "debian" or "security",
is mapped to a remote repository in the approx server's configuration file.
For example, the approx.conf file on the approx server might contain the lines
debian http://ftp.debian.org/debian
security http://security.debian.org
The mapping scheme is very simple. If the approx.conf file contains the line
repository http://remote-host/initial/path
then any request to the approx server of the form
http://approx-server/repository/rest/of/URL
is rewritten to
http://remote-host/initial/path/rest/of/URL
when there is a "cache miss", and that file is cached as
/var/cache/approx/repository/rest/of/URL
(Note that the repository name on the left-hand side is not included in the rewritten URL unless it is explicitly mentioned in the right-
hand side's initial path.)
FILES
/etc/approx/approx.conf
Configuration file for approx and related programs.
/var/cache/approx
Default cache directory for archive files.
SEE ALSO
approx.conf(5), inetd(8), approx-import(8), approx-gc(8), apt-get(8), sources.list(5)
AUTHOR
Eric Cooper <ecc@cmu.edu>
May 2011 APPROX(8)