Hi,

Iam new to Linux and have installed Redhat Linux Enterprise 4. I have noticed that the behaviour of memory usage to be weird. From the default startup, using "Free" , i checked the available memory to be 863836K. i left the system over 4 days without touching it. Upon checking, the available memory drops to 447528K. This is approximately 48% lost. No 3rd party application was installed yet.

Have a few questions
1) Is this a memory leak in RHEL4? Do I have a patch for it?
2) I notice that the cached memory is approx the size lost from the available memory, what is the behaviour of this cache and why wasn't the cache returned to to available memory?
3) Will the system crash ? I have yet to observe a bench mark for it to stabilise or have seen it reaching zero.
4) what is the best way to optimise the system? example killing of cpuspeed daemon,setting huge page file...etc

Appreciate your kind advice.

Regards,
Charles

Answers:
1) no, and no
2) (disk/page) cache is for performance. It will be "returned" when applications require it. Usually.
3) probably not, but maybe. In normal operation it won't reach zero.
4) leave it alone.

A use of the "search" button would have found plenty of relevant threads - including several pointing to this (excellent) article on the gentoo wiki - here.

What he said