Shared libraries (was Re: Window system bashing (was Re: X11 bashing))

[Richard Todd]

mohta at necom830.cc.titech.ac.jp (Masataka Ohta) writes:
>	mohta at necom830.cc.titech.ac.jp (Masataka Ohta) writes:
>>You may claim shared libraries reduces the amount of required memory.
>>But, even if you run all the command at the same time, total code
>>space consumed is only 24884KB (including non-library code). On the
>>other hand, if you run single X11 application, with shared library,
>>mere /lib/X11.a consumes 3.3MB of virtual (and often real, as libraries
>>tends to be scattered) memory.

 3.3 MEG???  That seems to me to be *way* out of line with what I see.
Here's what the shared library module for libX11 is like on my system
(Mac IIx, 68030 based machine, X11R4 compiled with gcc and Coolidge's 
shared library patches.) libX11_s is the actual shared library object file
that's mapped into the address space of any X client that wants to use the
shared lib:

% ll /usr/lib/X11/shlib/libX11_s
 27930  488 -rwxr-xr-x   1 root     root      244027 Mar 25 20:19 /usr/lib/X11/shlib/libX11_s*

And that's an unstripped binary; the actual size is:
% size -d /usr/lib/X11/shlib/libX11_s
Size of /usr/lib/X11/shlib/libX11_s:  141280
	Section         Size      Physical Address    Virtual Address
	.text            107656      1240465408         1240465408
	.data             28980      1240989696         1240989696
	.bss               4644      1241018676         1241018676

That means that worst case, Xlib will take up ~120K of memory.  That's 
*120K*, not 3.3M.  You're off by a factor of 30.  (Even if we throw in
libXt, libXmu, and libXaw, that's still a total of only  483K, still a far
cry from 3.3M.)  If standard MIT Xlib really compiles out to 3.3M on your
SONY NEWS workstation, remind me not to buy one to replace my Mac....

>If you run mwm, xdm and as many xterms as you want,

>	text	data	bss	dec	hex
>	1007616	192512	27168	1227296	12ba20	/usr/bin/X11/mwm
>	413696	86016	27792	527504	80c90	/usr/bin/X11/xdm
>	585728	139264	39376	764368	ba9d0	/usr/bin/X11/xterm

>still, total text size is below 2MB.

Well, I don't have mwm (not being willing to pay OSF one grand to make my 
windows look really ugly :-), but let's look at the memory sizes on my
Mac:
	text	data	bss	total
xterm: 146776   55804   32156	234736
xdm:   111004   27568   25272   163844
tvtwm: 150468   29884   30964   211316
So if we've got one of each client going (or more, considering that in any
decent Unix implementation the text is shared, and the data&bss usage for these
programs is considerably smaller than the text space), we've got ~600K for the
clients + ~480K for the shared libs, and add maybe 1M for the server, and 
we've got a total memory usage for X of ~2M.  Not exactly slim, but 
better than the 3.3M you were claiming for just the libraries alone. 

>So, shared library is NO solution even to reduce memory consumption of X11.

Seems to be doing good on my computer.  And even leaving aside memory 
considerations, compiling the entire X11R4 core client distribution with
shared libraries saved over 4M in disk space, just in not requiring every
client to contain a copy of the libraries.  (There are a *lot* of clients in
the std. X11R4 distribution...)
--
Richard Todd	rmtodd at uokmax.ecn.uoknor.edu  rmtodd at chinet.chi.il.us
	rmtodd at servalan.uucp
"Elvis has left Bettendorf!"