Ask Ubuntu is a question and answer site for Ubuntu users and developers. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I am using Ubuntu 12.10 with 4G RAM. I have changed SWAP to 10 and installed Preload. However, My system only use less than 1G RAM to cache and It remains more than 2G RAM standby.

How can I use up all RAM by cache? By this, I want to speed up open and run applications.

Thank you.

share|improve this question
An app only needs so much RAM. It's good you have plenty extra. Over time, more will get used. – Skaperen Oct 16 '12 at 12:52
up vote 3 down vote accepted

Don't worry about that. The cache optimizations run in the Linux kernel and trust me, when it becomes necessary to cache the data, it will be cached. Run the system for a few days and see what then happens.

Also note that the system has not precognitive powers and it can hardly cache your whole hard disk, so when you run a program for the first time, it will not be cached.

If you find yourself with too much free RAM on your hands and a specific application that relies on ultra low access and read times, you can always construct a RAM-disk. Normally, it is hardly worth an effort.

share|improve this answer
Thank you very much : ) – John Hass Oct 16 '12 at 16:49

In my opinion,your computer dont use your whole ram because it doesn't need whole of your ram.Or your cpu is not powerful to use your whole ram

share|improve this answer

One good use for your extra ram is to add the following line to /etc/fstab:

tmpfs                       /tmp                    tmpfs mode=0777 0 0

This gives you storage for temporary files in RAM. Take care to have enough swap space (2x Ram) so that the /tmp file system can grow.

Note: Files in /tmp are not expected to be preserved over reboot. So it's safe to do this. On the other hand, the directory /var/tmp MUST be preserved over reboots, so don't apply tmpfs to /var/tmp!!!

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.