Xubuntu Gutsy Gibbon - Low Resource Showoff - 2007-11-14

Eero Tamminen oak at helsinkinet.fi
Tue Dec 4 19:31:12 UTC 2007


On Friday 16 November 2007, Radomir Dopieralski wrote:
> Thu, Nov 15, 2007 at 10:29:07PM +0200:
> > It also seems that you don't have a session manager.  If you use gdm as
> > your session manager, by setting it to do autologin, you save quite a
> > bit of memory because it's its UI that uses most of RAM.  Gdm
> > configuring doesn't need any init scripts hacking and with autologin
> > you still get the normal Gdm login screen when you log out (instead of
> > e.g. shutdown).
> I always wondered why gdm doesn't release this memory once you log in...

If one doesn't count pictures (icons etc), most of the memory in a Gtk/Gnome
program goes to UI library initializations.  For example freetype/fontconfig
font data, locale data, Gtk widget class initializations and instances etc
(from instances program could get rid of, not from class initializations).
Then each library linked to a process takes a bit of memory for their
.data and .bss sections. etc.  Any graphics bloat this quickly (they are
decompressed and 32-bits/pixel in memory).

Typical Gnome application private memory usage is about a couple of megs
(as reported by SMAPS). Larger applications take a bit more.  You should
also note that just freeing things in code normally doesn't release it back
to system due to heap fragmentation (Glibc uses mmap() for >=128KB
allocs, those get back to the system immediately, however, except for
graphics, most allocs are smaller).

Only really feasible way to get rid of this would be restarting the process.

	- Eero

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