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I had browse for this issue in the forums, but the answers I found are not concrete or refers to older version of ubuntu.

I am using ubuntu 14 (3.13.0-35-generic #62-Ubuntu x86_64 x86_64 x86_64) and the RAM usage usually reach the 100%. even with a just-booted system, it is more than 50%.

is this normal in this version of ubuntu? for a 4 GB RAM machine it would be better to switch to lubuntu or other desktop with less RAM requirements? 

$ free -h
            total       used       free     shared    buffers     cached
Mem:         3.9G       2.3G       1.6G       23M       318M       1.0G
-/+ buffers/cache:      1.0G       2.9G
Swap:        4,0G         0B       4,0G
Florian Diesch
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cesarpachon
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    The free command doesn't tell you what is using the memory, only how much is being used. You need to examine what programs are using what amount, and possibly file bugs against some. Web browsers for example are very memory heavy programs. Limiting their runtime, and how many tabs you've opened in them, will help keep them down. – dobey Sep 11 '14 at 15:09
  • Do you have any problem with slowness etc? Linux will try to use all of your RAM... to speed things up. Do not worry... see also http://askubuntu.com/a/159358/16395 – Rmano Sep 11 '14 at 15:25
  • the output of the free command is just after a reboot, with none additional application opened. after opening Rubymine and Chromium, it is a matter of one hour or so before the system become completely unresponsive. – cesarpachon Sep 11 '14 at 20:51

1 Answers1

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There is no point in not using available RAM. Linux uses RAM that is not used by applications e.g. as disk cache to speed up disk access. If more RAM for apps is needed Linux shrinks the disk cache appropriately.

In the output of free the line starting with -/+ buffers/cache tells you the amount of RAM that is/could be used by apps.

In your example 1.0G (out of 3.9G available) is used by apps, and 2.9G are still available. 1.3G are used for cache and similar things and will be freed if needed.

Florian Diesch
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