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From: Robert Dewar <robert_dewar@my-deja.com>
Subject: Re: huge executable??
Date: 2000/05/15
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 <9EET4.760$pN4.423580@news.pacbell.net> <3920DA5B.2F56@club-internet.fr>
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In article <3920DA5B.2F56@club-internet.fr>,
  sikander@club-internet.fr wrote:

> I think that a reduced executable size is important, since
> that allows a better use of the CPU cache memory, so that
> could improve the speed of the program.

You are assuming that size of executable is directly related
to the working set in cache. There is no reason to make this
connection. Indeed it is obvious for example that static vs
dynamic linking, which has no effect on cache usage to speak
of, has a big effect on executable size.
>
> Concerning that problem, I suspect that, with GNAT, there is
> not a good elimination of the unused code.

Elimination of unused code will most certainly reduce executable
size but it won't help one bit in reducing cache pressure, since
obviously unused code never gets into the cache during
execution.

Similarly the presence or absence of debugging information has
a huge effect on executable size, but the debugging info is not
even loaded into memory, let alone the cache, if you are not
using the debugger.

I think to a first approximation, executable size of the null
program, measuring the base size of the run-time, has nothing
at all to do with execution efficiency. It may well have
something to do with functionality (e.g. a fancy exception
handler that prints out tracebacks will clearly take more space,
but there is no reason to worry about this additional space).

Basically the issue here boils down to disk costs alone. Seeing
as 128K bytes is approximately $0.004 worth of disk space, I
don't see this as a big worry these days :-)



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