Re: Debian shared libs use far more memory than required

[Thiemo Seufer <ths@networkno.de>]

Andreas Barth wrote:
[snip]
> > DEBIAN PACKAGE FROM REPOSITORY:
> > 11 .rodata      000840cb  000000000021a180  000000000021a180   ...
> > 21 .data         000233c0  00000000003f1d60  00000000003f1d60  ...
> > 
> > MY OWN RECOMPILED DEBIAN PACKAGE:
> > 11 .rodata       000a43ad  00000000001f3180  00000000001f3180  ...
> > 21 .data         00000748  00000000003f3460  00000000003f3460  ...
> > 
> > That's 0x0233c0-0x748 = 140KB moved from shared to non-shared
> > 
> > 140KB of non shared memory per GTK application is HUGE!!!

Fortunately it is not as bad as it sounds iff the constant data is
collated together in larger chunks. The kernel does copy-on-write,
if a .data page is never written, the memory usage is effectively
the same.

[snip]
> > My first though was that the official debian package was probably 
> > compiled with a different version of gcc.
> > However, I could not reproduce the official package size with gcc-3.3, 
> > gcc-3.4 and gcc-4.0 so the problem
> > is probably elsewhere: libtool? binutils ?

The immediate suspect is binutils, particularily ld. It might be
interesting to do test compiles with an older binutils version
(2.15 vs. 2.16?) and see if the problem is reproducible.


Thiemo