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Re: question regarding prelinking (was: (inc. note from dpkg developers) (was:Bug#XXXXXX: (far too many packages) needs rebuilt for prelinking))



Hi,

On Sat, Jan 18, 2003 at 12:17:48PM +0100, Sebastian Rittau wrote:

> On Fri, Jan 17, 2003 at 11:59:12PM +0100, Emile van Bergen wrote:
> 
> > I wasn't referring to GTK+. I specifically mentioned GTK+ and the rest
> > of Gnome as the point where a good split could be made.
> 
> Ok, but there many GNOME applications out there that happen to link only
> to parts of GNOME.

But that doesn't matter. As long as you have at least one application
running that uses certain parts, and another that uses other parts, then
there is no wastage at all by putting all of gnome into one .so.
Libraries don't get loaded into RAM after all, they get mapped. 

Only if no application whatsoever uses eg. the printing parts, is
mapping those a waste of page tables. However, even while those parts
are currently in different .so's, are they currently often loaded,
whether you actually ever press 'print' or have any printers or not. So
the waste occurs anyway.

In sort, "that's no good reason".

If I understand ELF correctly, then having multiple .so's is bad for
another reason. The more instructions a library contains that don't
refer to places relative to wherever the library got mapped, but to
other, lower level libraries, the more instructions need fixing up at
run time using the mapped addresses of /other/ libraries, because they
may be at different places for different applications.

And each time a page of code in a library contains instructions that
must be fixed up at load time for an application, that page cannot be
shared among applications. A waste of memory.

Cheers,


Emile.

-- 
E-Advies / Emile van Bergen   |   emile@e-advies.info
tel. +31 (0)70 3906153        |   http://www.e-advies.info

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