11-12-2014
There is no swap space use with mmap() unless you choose the more exotic options. The basic mmap() swaps in file pages directly to RAM, giving you a way to work huge files with all of RAM as a cache. If you overmap a file, you can write pages. Empty pages can exist, supporting sparse matrices. This is a very powerful door into application use of VM and full exploitation of RAM.
Sorting small into larger in steps allows the problem to periodically expand to the next level of storage: from the caches to the RAM to the disk. The only flaw is that it might be good to merge more than 2 at a time, so when you get to the disk size merges, there is just one or at least fewer. The merge could use some sort of comparison tournament tree to do the merge, sized to fit in L1 cache, where each replacement item needs to be fit into the tree before using the smallest from the tree. Note that each item will take a whole page of RAM, or two, and N-N+2 lines of L1 cache, depending on the cache and item sizes and page/line offsets. Trying to fill L1 cache is fraught with difficulty, as many items may demand the same cache bucket, so it pays to shoot a bit low, like 1/4 - 1/2 L1 cache size.
10 More Discussions You Might Find Interesting
1. UNIX for Dummies Questions & Answers
I am trying to understand the webserver log file for an error which has occured on my live web site.
The webserver access file is very big in size so it's not possible to open this file using vi editor. I know the approximate time the error occured, so i am interested in looking for the log file... (4 Replies)
Discussion started by: sehgalniraj
4 Replies
2. Shell Programming and Scripting
Hi All
I have approximately 10 files that are at least 100+ MB in size. I am importing them into a DB to output them to the web. What i need to do first is clean the files up so i dont have un necessary rows in the DB. Below is what the file looks like:
Ignore the <TAB> annotations as that... (4 Replies)
Discussion started by: caddyjoe77
4 Replies
3. UNIX for Dummies Questions & Answers
How do we check 'large files' is enabled on a Unix box -- HP-UX B11.11 (2 Replies)
Discussion started by: ranj@chn
2 Replies
4. UNIX for Dummies Questions & Answers
I was wondering how sort works.
Does file size and time to sort increase geometrically?
I have a 5.3 billion line file I'd like to use with sort -u I'm wondering if that'll take forever because of a geometric expansion?
If it takes 100 hours that's fine but not 100 days.
Thanks so much. (2 Replies)
Discussion started by: dcfargo
2 Replies
5. Shell Programming and Scripting
hello all,
kindly i need your help, i made a script to print a specific lines from a huge file about 3 million line. the output of the script will be about 700,000 line...the problem is the script is too slow...it kept working for 5 days and the output was only 200,000 lines !!!
the script is... (16 Replies)
Discussion started by: m_wassal
16 Replies
6. Shell Programming and Scripting
Hello everyone!
I have 2 types of files in the following format:
1) *.fa
>1234
...some text...
>2345
...some text...
>3456
...some text...
.
.
.
.
2) *.info
>1234 (7 Replies)
Discussion started by: ad23
7 Replies
7. UNIX for Dummies Questions & Answers
Hi all,
I have problem with searching hundreds of CSV files, the problem is that search is lasting too long (over 5min).
Csv files are "," delimited, and have 30 fields each line, but I always grep same 4 fields - so is there a way to grep just those 4 fields to speed-up search.
Example:... (11 Replies)
Discussion started by: Whit3H0rse
11 Replies
8. Solaris
Hello everyone. Need some help copying a filesystem. The situation is this: I have an oracle DB mounted on /u01 and need to copy it to /u02. /u01 is 500 Gb and /u02 is 300 Gb. The size used on /u01 is 187 Gb. This is running on solaris 9 and both filesystems are UFS.
I have tried to do it using:... (14 Replies)
Discussion started by: dragonov7
14 Replies
9. UNIX for Advanced & Expert Users
Hello all -
I am to this forum and fairly new in learning unix and finding some difficulty in preparing a small shell script. I am trying to make script to sort all the files given by user as input (either the exact full name of the file or say the files matching the criteria like all files... (3 Replies)
Discussion started by: pankaj80
3 Replies
10. Shell Programming and Scripting
Hello,
I have a very large file of around 2 million records which has the following structure:
I have used the standard awk program to sort:
# wordfreq.awk --- print list of word frequencies
{
# remove punctuation
#gsub(/_]/, "", $0)
for (i = 1; i <= NF; i++)
freq++
}
END {
for (word... (3 Replies)
Discussion started by: gimley
3 Replies
LEARN ABOUT HPUX
wrap-and-sort
WRAP-AND-SORT(1) General Commands Manual WRAP-AND-SORT(1)
NAME
wrap-and-sort - wrap long lines and sort items in Debian packaging files
SYNOPSIS
wrap-and-sort [options]
DESCRIPTION
wrap-and-sort wraps the package lists in Debian control files. By default the lists will only split into multiple lines if the entries are
longer than 80 characters. wrap-and-sort sorts the package lists in Debian control files and all .install files. Beside that wrap-and-sort
removes trailing spaces in these files.
This script should be run in the root of a Debian package tree. It searches for control, control.in, copyright, copyright.in, install, and
*.install in the debian directory.
OPTIONS
-h, --help
Show this help message and exit.
-a, --wrap-always
Wrap all package lists in the Debian control file even if the entries are shorter than 80 characters and could fit in one line line.
-s, --short-indent
Only indent wrapped lines by one space (default is in-line with the field name).
-b, --sort-binary-packages
Sort binary package paragraphs by name.
-k, --keep-first
When sorting binary package paragraphs, leave the first one at the top. Unqualified debhelper(7) configuration files are applied to
the first package.
-n, --no-cleanup
Do not remove trailing whitespaces.
-d path, --debian-directory=path
Location of the debian directory (default: ./debian).
-f file, --file=file
Wrap and sort only the specified file. You can specify this parameter multiple times. All supported files will be processed if no
files are specified.
-v, --verbose
Print all files that are touched.
AUTHORS
wrap-and-sort and this manpage have been written by Benjamin Drung <bdrung@debian.org>.
Both are released under the ISC license.
DEBIAN
Debian Utilities WRAP-AND-SORT(1)