Joshua C. wrote:
2009/2/7 Adrian Joian <adrian.joian@xxxxxxxxxxxxxxxx>:
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.
That's another aspect of linux VM subsystem (read:
http://lwn.net/Articles/83588/).
To be short, kernel decides to swap out unused program pages from
physical memory to the disk.
This clears physical memory for cache use.
Example: You open OOo Writer and leave it alone for half an hour.
Kernel decides You aren't going to use it soon, and swaps (all) it's
pages out.
That gives the kernel additional ~100 MBs to cache the movie You're
editing in Kino.
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