11-14-2014
sort is a merge-sort, which has no need or use for gigantic memory buffers -- unless you want to use more memory than is available and eat into swap, that is. If you have very high-performance swap that can be useful. Otherwise, leave -buffer-size out and let it manage itself.
-parallel should be a big performance gain -- if you have enough memory that it doesn't need to thrash your disk, and fast enough disks to keep up. If not, it will just make things worse.
I don't see any something-for-nothing solutions here. You won't squeeze out anything but percents here and there unless you deal with the bottlenecks. Every time you tell it "use more resources" and it slows down, that's a bottleneck. Every time you tell it "use less files" and it speeds up, that's a bottleneck.
1) More RAM -- the more the OS can cache, the less it has to wait on the disk. Brute force, but there's a reason RAM is popular, it works really well.
2) A different temp space. If you put /tmp/ on a different disk spindle than the file you are sorting, you can get the bandwidth of two disks instead of splitting the bandwidth of one disk several ways (and eliminate a lot of disk thrashing time). It doesn't have to be /tmp/ of course, sort -T puts the files wherever you ask.
3) Faster swap. Eat up more RAM than you have available and depend on an SSD to make up the difference. This could be good, though sounds rather complicated to me.
Last edited by Corona688; 11-14-2014 at 12:29 PM..
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LEARN ABOUT DEBIAN
dphys-swapfile
DPHYS-SWAPFILE(8) System Manager's Manual DPHYS-SWAPFILE(8)
NAME
dphys-swapfile - set up, mount/unmount, and delete an swap file
SYNOPSIS
dphys-swapfile setup|swapon|swapoff|uninstall
DESCRIPTION
dphys-swapfile computes the size for an optimal swap file (and resizes an existing swap file if necessary), mounts an swap file, unmounts
it, and and delete it if not wanted any more.
OPTIONS
There is only one parameter, an command, which can be either of these:
setup Tells dphys-swapfile to compute the optimal swap file size and (re-)generate an fitting swap file. Default it 2 times RAM size. This
can be called at boot time, so the file allways stays the right size for current RAM, or run by hand whenever RAM size has changed.
swapon and swapoff These run the swapon and swapoff commands on the swapfile. Note that direct swapon/off from /etc/fstab is not possible,
as that is (at least on Debian) done in the same script that mounts /var (which is where the swap file most likely resides). And we
need to do our setup between those actions. So pass up /etc/fstab, and do our own swapon/off.
uninstall
Gets rid of an unwanted swap file, reclaiming the disk space.
CONFIG
The config file /etc/dphys-swapfile allows the user to set up the working environment for dphys-swapfile.
This config file is a sh script fragment full of assignments, which is sourced. Standard sh syntax rules apply. Assignments are:
CONF_SWAPFILE
Set where the swap file should be placed. Defaults to /var/swap. It is unlikely that you will need to change this, unless you have
very strange partitioning, and then you will most likely be using an swap partition anyway.
CONF_SWAPSIZE
Force file size to this. Default is 2*RAM size. This is unlikely to be needed, unless in strange diskspace situations. Note that
swap enabled and smaller than RAM causes kernal-internal VM trouble on random systems.
CONF_SWAPFACTOR
Set the relation between RAM and swap size. Must be an integer. Defaults to 2 which means swap size = 2 * RAM size
CONF_MAXSWAP
Set maximum size of the swap file in MBytes. Defaults to 2048 which was the former kernel limit for the swapfile size and is now a
limit to prevent unusual big swap files on systems with a lot of RAM.
FILES
/etc/dphys-swapfile
user config
$CONF_SWAPFILE
the swap file, target of the whole action (defaults to /var/swap)
EXAMPLES
dphys-swapfile is usually run at system startup and shutdown from an /etc/init.d (or /etc/rc.d) script, such as this (minimal) one:
#!/bin/sh
# /etc/init.d/dphys-swapfile - automatically set up an swapfile
# author franklin, last modification 2004.06.04
# This script is copyright ETH Zuerich Physics Departement,
# use under either modified/non-advertising BSD or GPL license
case "$1" in
start)
/sbin/dphys-swapfile setup
/sbin/dphys-swapfile swapon
;;
stop)
/sbin/dphys-swapfile swapoff
;;
esac
exit 0
If an sysadmin wants to have his swapfile in annother place, say /var/run/swap, he can use:
In /etc/dphys-swapfile:
CONF_SWAPFILE=/var/run/swap
AUTHOR
franklin@phys.ethz.ch, http://www.phys.ethz.ch/~franklin/
D-PHYS Swapfile Tools 2006.09.15 DPHYS-SWAPFILE(8)