We put some effort in making busybox avoid using more memory
than absolutely needed, including NOMMU systems.
In order to show where we are now and what can (should?) be
ultimately attained, I built several versions of busybox
with nearly identical config, all against static uclibc, and
collected pmap $PID output for 'busybox sleep 10'.

What is important here is that code section is shared among
all running busybox processes (even some NOMMU systems are capable
of reusing code pages for all running instances),
while [heap] and [stack] areas are private per-process areas.
Therefore making them smaller is good, even if it makes code
a bit larger.

Last printout shows similar data for small, statically linked
application (linked against dietlibc). This is probably as small
memory usage as we can ever achieve. Judge for yourself how close
we (busybox + uclibc) are to that.

busybox-1.2.2.1/busybox sleep 10:
   text    data     bss     dec     hex filename
 734976    7056  230396  972428   ed68c /.share/usr/srcdevel/bbox/comparison/busybox-1.2.2.1/busybox
08048000      720K r-xp /.share/usr/srcdevel/bbox/comparison/busybox-1.2.2.1/busybox
080fe000      224K rwxp [heap]
77cf1000       84K rw-p [ stack ]
080fc000        8K rwxp /.share/usr/srcdevel/bbox/comparison/busybox-1.2.2.1/busybox
ffffe000        4K r-xp [vdso]

busybox-1.3.2/busybox sleep 10:
   text    data     bss     dec     hex filename
 739764    6576   74300  820640   c85a0 /.share/usr/srcdevel/bbox/comparison/busybox-1.3.2/busybox
08048000      724K r-xp /.share/usr/srcdevel/bbox/comparison/busybox-1.3.2/busybox
77c6f000       88K rw-p [ stack ]
080ff000       72K rwxp [heap]
080fd000        8K rwxp /.share/usr/srcdevel/bbox/comparison/busybox-1.3.2/busybox
ffffe000        4K r-xp [vdso]

busybox-1.4.2/busybox sleep 10:
   text    data     bss     dec     hex filename
 720472    3504   67484  791460   c13a4 /.share/usr/srcdevel/bbox/comparison/busybox-1.4.2/busybox
08048000      704K r-xp /.share/usr/srcdevel/bbox/comparison/busybox-1.4.2/busybox
77ea6000       84K rw-p [ stack ]
080f9000       68K rwxp [heap]
080f8000        4K rwxp /.share/usr/srcdevel/bbox/comparison/busybox-1.4.2/busybox
ffffe000        4K r-xp [vdso]

busybox-1.5.1/busybox sleep 10:
   text    data     bss     dec     hex filename
 720288    2640   41820  764748   bab4c /.share/usr/srcdevel/bbox/comparison/busybox-1.5.1/busybox
08048000      704K r-xp /.share/usr/srcdevel/bbox/comparison/busybox-1.5.1/busybox
77cfb000       88K rw-p [ stack ]
080f9000       40K rwxp [heap]
080f8000        4K rwxp /.share/usr/srcdevel/bbox/comparison/busybox-1.5.1/busybox
ffffe000        4K r-xp [vdso]

busybox-svn/busybox sleep 10:
   text    data     bss     dec     hex filename
 710112    1392   25276  736780   b3e0c /.share/usr/srcdevel/bbox/comparison/busybox-svn/busybox
08048000      696K r-xp /.share/usr/srcdevel/bbox/comparison/busybox-svn/busybox
77eb1000       88K rw-p [ stack ]
080f7000       24K rwxp [heap]
080f6000        4K rwxp /.share/usr/srcdevel/bbox/comparison/busybox-svn/busybox
ffffe000        4K r-xp [vdso]

A small app (multilog) built against dietlibc:
   text    data     bss     dec     hex filename
  14029     172    4560   18761    4949 /app/daemontools-0.76/bin/multilog
77c3b000       88K rwxp [ stack ]
08048000       16K r-xp /app/daemontools-0.76/bin/multilog
0804d000        4K rwxp [heap]
0804c000        4K rwxp /app/daemontools-0.76/bin/multilog
ffffe000        4K r-xp [vdso]

Script used for generation of the above output:

#!/bin/sh
for f in */busybox; do
    test -x $f || continue
    echo "$f sleep 10:"
    $f sleep 10 &
    pid=$!
    sleep 1
    size `pwd`/$f
    pmap $pid | env - grep "^[0-9a-f][0-9a-f]* " | sort -r -t " " -k2,999
done
echo "A small app (multilog) built against dietlibc:"
pid=871
size /app/daemontools-0.76/bin/multilog
pmap $pid | env - grep "^[0-9a-f][0-9a-f]* " | sort -r -t " " -k2,999