Further memory question [was: Clear the computer's memory?]

[R Kimber]

On Thu, 30 Mar 2006 08:00:22 -0500
Kent Borg <kentborg at borg.org> wrote:

> On Thu, Mar 30, 2006 at 01:08:49PM +0100, R Kimber wrote:
> > I have a further question about memory use. As I write, having been
> > forced to reboot about 10 hours ago, and having 4 not very
> > demanding apps open, plus the background stuff that is started at
> > boot, Gkrellm tells me that I have 1702MB of memory free out of 2GB.
> 
> One subtlety about Linux memory usage is that it figures that if you
> have memory, it should use it!  It should use it in anyway that will
> help the computer run.  Think of the memory as shelf space at the
> local library--you want plenty of it, and you want those shelves in
> use, not empty.
> 
> Memory will be used to cache disk contents, it will be used for IO
> buffers, it will be used to page more of your program's data into RAM.
> It will also be used by programs that are, well, using lots of RAM,
> including some that start to gobble up lots of swap too.
 
> Does that make Linux's behavior clearer?

It's not linux's behaviour that bothers me.  What I'm puzzled about is
that when I boot up, linux will allocate memory as you describe, and
Gkrellm will report an amount free. I'm not clear why this free amount
should change so drastically after some hours of use, when caches etc
have already been allocated and I'm not starting new apps.  At the
moment, I still have about 1714MB free, but by tomorrow I'll bet it
will be down to 700MB.  I don't usually use Firefox, BTW.

- Richard
-- 
Richard Kimber
http://www.psr.keele.ac.uk/