Re: Looking for a smart linker for GNAT/DOS

[kilgallen@eisner.decus.org (Larry Kilgallen)]

In article <5jac72$atr$1@gonzo.sun3.iaf.nl>, geert@gonzo.sun3.iaf.nl (Geert Bosch) writes:
> Robert Dewar (dewar@merv.cs.nyu.edu) wrote:
>       One thing that can help is the systematic use of DLL's or
>       whatever shared libraries are called on your machine. Since
>       only what you actually use is loaded into physical memory,
>       and since your image then does not contain the code, the
>       problem is largely alleviated.
> 
> Actually, this only increases the importance of smart linkers or 
> compilers. In the example below I will assume a system with 4 kB
> VM pages loaded on demand.
> 
> Consider a program using a library of 50 subprograms of 500 bytes
> in size on average. When the program uses only 6 of the subprograms
> in the package, chances are that these 6 subprograms are all in
> different VM pages, so using these 6 subprograms will cause nearly
> the entire library to be loaded.

But shared libraries are not just for a single program, they are for
multiple programs.  So  although the set of people using your program
on a given machine may only use 6 subprograms, those using other programs
at the same time which use the same shared library will be using different
subprograms.  They may even have preloaded the six you need by accident !

Obviously all of this depends on OS capability.

(Contrary to the thread topic, I believe the discussion indicates we
are talking about more than just single-user DOS systems.)

Larry Kilgallen