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.

  • An app only needs so much RAM. It's good you have plenty extra. Over time, more will get used.
    – Skaperen
    Oct 16, 2012 at 12:52

3 Answers 3


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.


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!!!


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

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