As promised, here is the chart of a Linux Ubuntu server 24 hours or so after turning off swap (it is still off).
As mentioned, on this server there is plenty of memory (for the applications) so there is zero issue having swap turned off:
I can continue this for a few of my "busy servers", some very busy, but all have plenty of RAM, so all will perform just fine with swap turned off (since they do not really use any swap with it turned on).
Anyway, I don't want to beat this dead horse any longer...
Computer RAM is cheap.... if your system is swapping, buy more RAM.
Hi,
Does any one know what tool to use to visualize how is memory layed out for C on linux systems. I mean how much stack portion is used in functional call.
Where exactly does the argument to function sit in memory ?
I have written small program pasted below. But I am not able to infer... (3 Replies)
HI
I'm a rookie in C programming and I'm working in Monta Vista Linux. I have to write a program that displays free memory. I have memtester(allready written by someone else) and now I have to type how much amount of memory tester will test and I want that memtester finds out himself how much of... (11 Replies)
What's the best way to find out how much memory is being used/available? I tried using free, but I didn't quite understand the output. Can someone explain it?
$ free
total used free shared buffers cached
Mem: 16304536 16256376 48160 0 ... (6 Replies)
Hi,
I having problem with my linux machine
it have 6Gb physical memory and somehow it always almost coming to the bottom neck and than it start writing to the swap memory
you can see that there is more than 4G in cahce, is there any way to clean the cache or to limit it to 2Gb?
host1... (6 Replies)
Hi All,
We are using the linux servers and need to track the memory utilization of the box. Could anyone advice how the same can be achived.
:) (1 Reply)
I am trying to create an application that will be able to sniff memory of other applications.
I am not completely new to systems programming but I am not sure how to go about this task. I understand that accomplishing this mainly require these steps.
1: Get a list of processes
2: Find the... (2 Replies)
Hi ,
As I am new to Linux server, I am facing some doubts like: On linux server virtual memory usage goes to 99%, but I have Threshold limit of 95%. So it crossed the threshold limit and alarmd.
Yesterday I moniterd the server using TOP command, and found some of Tibco process was consuming... (4 Replies)
Dear Friends ,
I am confused about shared memory in Linux . plz look @ the below output :
$ df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 126G 61G 59G 52% /
tmpfs 1.7G 0 1.7G 0% /dev/shm
Here , I see that every time... (1 Reply)
Hello, I am using Linux os.
$ df -k /dev/shm
Filesystem 1K-blocks Used Available Use% Mounted on
tmpfs 2023256 1065000 958256 53% /dev/shm
$
Based on my google this, it is shared memory. What is this shared memory and where exactly it is used? Can you... (5 Replies)
Discussion started by: govindts
5 Replies
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)