How to reduce cached memory?

[Gregory Maxwell]

On Fri, Feb 6, 2009 at 5:57 PM, Joshua C. <joshuacov at googlemail.com> wrote:
> I have kde 4.2 and f9. After 2+ hours on my computer it has about
> 1,4GB cached memory. I don't see him releasing this memory after time.
> I know it comes from the apps being open but it seems the kernel
> "never" releases the memory after the app terminates. How to make the
> kernel free this memory? I've seen similar cases with kde 3.5.10 and
> f8 and f7. I know kde eats memory but this is too much. Who caches so
> much of it? Why?
>
> The mashine has 2,6 GB RAM (still x86) and 512mb swap which is rarely
> used (~ 50mb at most) and combined cached + app memory totals about 2
> gb.

Why do you regard this as a problem?

100% of your memory should be used at all times. Memory which is
unused is wasted. To prevent waste the Linux kernel keeps frequently
used things from disk in memory but (clean) Cached memory can be
dropped as soon as an application requests ram so it is "as good as
free" from a usage perspective.