I usually do this in a few steps. You do need to be root to do this. First I want to see what is currently being used.
free
Then I run the actual commands that empty the swap:
swapoff -a && swapon -a
Then I check what is being used after doing this.
free
I have these three steps in a script and then I just run the script, but, the commands could easily be run from the command line.
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13 comments:
Thanx it help for me
Thanks. I had puzzling situation with 4G RAM mostly free but a whole G of swap in use.
Your command line cleared swap although I'm still a bit puzzled.
top shows Swap: 2031608k total, 0k used, 2031608k free, 2031472k cached
What is that cached swap?
colymoore@gmail.com
Yes! Did exactly what I was wanting to do.
yup...really good advice...only that I don't think you really need the exact amount of free RAM as the amount of occupied swap...
I had 700 MB of used RAM out of 2 GB and 1.3 GB of swap. after using your commands I have 1.3 GB of RAM used and no swap :P
Thank you anyway
Thankkkkkkks, just what I was looking for.
Thanks Dude. Short and sweet. Did exactly what I needed. Much Appreciated!
Rather use:
sync; echo 3 > /proc/sys/vm/drop_caches
It is better to sync before messing with cache
Thanks I was exactly looking for this.
Burhan
Below will decrease number incached colum and increased number in fee Mem colum. No effect for swap usages.
sync; echo 3 > /proc/sys/vm/drop_caches
[root@uksysops004 ~]# free -to
total used free shared buffers cached
Mem: 4046272 3924208 122064 0 334268 967444
Swap: 8191992 1499496 6692496
Total: 12238264 5423704 6814560
# sync; echo 3 > /proc/sys/vm/drop_caches
# free -to
total used free shared buffers cached
Mem: 4046272 2458000 1588272 0 404 59940
Swap: 8191992 1499496 6692496
Total: 12238264 3957496 8280768
#
The best super all in one clear cache, buffers and swap file in one go:
sync && sudo /sbin/sysctl vm.drop_caches=3 && sudo swapoff -a && sudo swapon -a
You might need to alter the permissions on the sysctl or vm.drop_caches file, or run the following command under su/root:
sync && /sbin/sysctl vm.drop_caches=3 && swapoff -a && swapon -a
Works flawless, every time :)
-Jamie M.
Also, /proc/sys/vm/swappiness by default is 60, with 100 being aggressive swapping, 0 being "use swap only when actually running out of RAM"
Nice quick article. Agreed about sync first, though. Just in case.
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