Memory Usage by X

Paulo J. Matos pocm at
Sun Dec 10 14:31:35 PST 2006

On 12/10/06, Andrew Clayton <andrew at> wrote:
> >
> > One obvious thing you can do with it is cache disk reads and write to
> > speed up the system.  You have 1GiB of memory and free is showing that
> > your kernel has used 931MiB of that for buffer cache.  Your memory is
> > not used because of X11 at all.  The kernel is caching data from disk.
> I think your are misreading that.
> The buffers/cache takes into account how much ram is being used for
> buffers/cache so after that has been accounted for, he has 931MB used.
> See the free in the first line is 18MB and the free in the second like
> is 79MB (18+4+57) taking the buffers and cache into account.
> Thus he is only using 61MB for buffers and cache. Some memory will
> also be used up in the slab (slabtop can show how much), assuming he's
> running Linux.

Thanks for the reading of the data. And for the reference to slabtop.
Didn't know about it. Quite interesting!

> The X process does seem to grow overtime esp with extended use of
> Firefox/Mozilla. Restarting them does free some up, also using things
> like mplayer/xine seems to sometimes shrink the X process slightly.
> Also he mentions he's using Konsole, I've seen Konsole use tons of
> pixmap memory if you use a background image or use the fake
> transparency.

Well, I really don't use konsole with a background image or
transparency but I some times open firefox and I open xine a lot.
Moreover, I'll leave once again my laptop open. I hope to have more
info soon based on the reference apps you gave.


Paulo Matos

> Andrew
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Paulo Jorge Matos - pocm at
PhD Student @ ECS
University of Southampton, UK

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