How to reduce cached memory?

[Joshua C.]

2009/2/7 Adrian Joian <adrian.joian at fedoraproject.ro>:
> Hello,
>
> Well, if you really want to decrease cache levels you could at schedule
> at random times the following command:
> echo 1 > /proc/sys/vm/drop_caches
>
> Adrian JOIAN
> fedoraproject.ro
>
> Chris Tyler wrote:
>> On Fri, 2009-02-06 at 23:57 +0100, Joshua C. 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.
>>>
>>
>> Hi Joshua,
>>
>> Memory is being used for cache basically because it's not being used for
>> anything else. The kernel will gladly use that memory for other purposes
>> when it's needed -- but until then, there's no harm in keeping disk data
>> around in otherwise-unused memory just in case it's needed later.
>>
>> This is why the "free" command shows a "-/+ buffers/cache" line, which
>> shows you what the memory picture is without the cache (i.e., the memory
>> that is truly available when needed):
>>
>>   $ free
>>                total     used    free  shared buffers cached
>>   Mem:       4061388  3796632  264756       0  259244 570224
>>   -/+ buffers/cache:  2967164 1094224
>>   Swap:      4194296  2092276 2102020
>>
>>
>> -Chris
>>
>>
>
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Than you everyone for the replies. Swapping do occurs (although
rarely) but this is not my concern. What I don't like is the fact,
that the kernel fills the memory with "what he thinks I would use/like
or have already used". I didn't know it will use the cached memory in
case it's needed.

But then is the question: When swapping occurs where have the other
2,6 gb ram gone? I don't believe I've opened so many apps that can
consume so much memory.