From: jwinstea@fenris.claremont.edu (Jim Winstead Jr.)
Subject: Re: shared libs
Organization: Harvey Mudd College, WIBSTR
Date: Fri, 14 Aug 1992 05:15:38 GMT

In article <1992Aug14.040459.29047@cs.ucf.edu> hab@engr.ucf.edu (Hubert Bahr) writes:
>In article <1992Aug13.183740.24742@ods.com> david@ods.com (David Engel) writes:
>>
>>Yes, there is a slight performance hit but it's not even noticable
>>for most programs.  One of these days, when I get the time and 
>>inclination, I'm going to do some more accurate benchmarking.  The 
>>2-4 % I measured a long time ago still seems a little high to me.  
>>Of course, nobody is forcing you to use the jump table libs.  If you
>>need that last bit of performance, you can always use the regular 
>>shared libs.
>
>Not when HJ only provides GCC only as a binary using jump tables for
>it.  We are forced to use at least GCC with jump tables.

Ahem.  prep.ai.mit.edu:/pub/gnu/gcc-2.2.2.tar.Z, and
banjo.concert.net:/pub/Linux/GCC/gcc-2.2.2.tar.Z will give you the
most current source for GCC.  If you're that ocncenred with not using
jump-table libs, compile it yourself.  :)

>I for one want to know that I have an up to date source library for all
>the software I use.  I also want this library compilable with the current
>make files and utilities.  Yes it will take extensive work to automate
>this recompile effort, but I think the dividends are multifold, 1st If

Um, I'm glad you have the diskspace to keep the source around, and the
time to recompile everything.  Most of us don't.

>I check things when they have just been changed, the changers will probably
>be more responsive to bug reports.  2  New versions of GCC and libraries
>are usually to fix bugs or performance flaws.  How can I take advantage
>of those changes without recompiling anyway.  3.  I can take advantage

Most GCC/libc releases are to fix bugs in libc - with jump table
libraries, just copy the new library into place and *all* binaries
linked against the jump table libraries use the new routines.  No
recompilation necessary.

>of all information available from GDB to make the programs better.  4  I

Well, you have to link with -g to do anything really special with GDB,
anyways, so you're already linking against static libs in that case.

>In this environment I see absolutely no benefit with jump tables.  True
>freedom with software is to have complete control to make desired changes
>without undue suprises.

I would say that you are in an extremely special-case environment.  I
doubt anyone else is looking forward to recompiling entire source
trees when each new bugfix to the libraries come out.

There may be a very slight performance hit for using jump table
libraries.  I'm willing to take that hit for the amount of time it
will save me - I'm sick of recompiling all the programs I have around
every time a new gcc comes out.  With 2.2.2d, it should be the last
time I'll have to recompile for a nice long time.
-- 
                                    +      Jim Winstead Jr. (CSci '95)
                                    |      Harvey Mudd College, WIBSTR
                                    |   jwinstea@jarthur.Claremont.EDU
                                    + or jwinstea@fenris.Claremont.EDU
Newsgroups: comp.os.linux