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clean up memory on linux

Terminal - clean up memory on linux
sync; echo 3 | sudo tee /proc/sys/vm/drop_caches
2010-05-23 11:39:35
User: bandie91
Functions: echo sudo sync tee
9
clean up memory on linux

where proc filesystem mounted under /proc

Alternatives

There are 15 alternatives - vote for the best!

Terminal - Alternatives
sync && echo 3 | sudo tee /proc/sys/vm/drop_caches
sync; echo 3 > /proc/sys/vm/drop_caches
sysctl -w vm.drop_caches=3
sudo sync && sudo echo 3 | sudo tee /proc/sys/vm/drop_caches
2012-03-17 08:27:58
User: StephenJudge
Functions: echo sudo sync tee
Tags: memory cache
-1

"That's it. Not much to see here. The first command writes any cache data that hasn't been written to the disk out to the disk. The second command tells the kernel to drop what's cached. Not much to it. This invalidates the write cache as well as the read cache, which is why we have the sync command first. Supposedly, it is possible to have some cached write data never make it to disk, so use it with caution, and NEVER do it on a production server. You could ... but why take the risk?

As long as you are running a post 2.6.16 kernel,..."

Source: http://ubuntuforums.org/showpost.php?p=3621283&postcount=1

free && sync && echo 3 > /proc/sys/vm/drop_caches && free

Know a better way?

If you can do better, submit your command here.

What others think

Why would you want to do this?

Comment by DNSpyder 341 weeks and 2 days ago

Nice, but what would you use it for other than prettying up /usr/bin/free for management's consumption?

Comment by sufoo 341 weeks and 2 days ago

Buffers and caches in linux only use unused memory, i.e. memory not used by processes. So it's incorrect to think that you are making more memory available for programs by using this, in general. As soon as an application makes a big memory request, the kernel may satisfy that request by "dropping" enough buffers or cache to satisfy the request. Because unused memory is a terrible thing to waste. :-) If you do this, and then want to cache a file's contents (if there is memory available) then simply do

cat filename > /dev/null

if you run htop you can see the cache fill up as cat reads this file and automatically uses cache if it can.

Comment by bwoodacre 341 weeks and 2 days ago

bwoodacre: its news for me.

i had hope it decrease number of pagefaults

Comment by bandie91 341 weeks and 1 day ago

under what situation i should use this command??

Comment by criver 339 weeks and 3 days ago

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Comment by xiaozhengm 45 weeks and 1 day ago

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