Re: Optimizing for PentiumMMX?
John Gay <johngay@eircom.net> wrote:
> I've been a faithful Debian user for several years now and quite enjoy
> the 'ready-to-install' packaging of Debian. I must say that the .deb
> format seems to be one of the best and apt-get and it's friends are a
> god-send for those of us who have better things to do than figure out
> all the in's-N-out's of UNIX-type systems. In fact, the only time I've
> had problems was when mixing stable, testing and unstable. Yes,
> self-inflicted ;-)
>
> Now, being un-employed for a while, and hoping to shift my skills from
>
> hardware-cetric towards programming and system admin, I find plenty of
> time on my hands now.
>
> The only complaint I have about Debian is the time-lag from software
> release and inclusion in Debian. No harm to the great people who
> dedicate great amounts of time packaging stuff for Debian, but
> sometimes I'd like to play with some BETA releases.
>
> With this in mind, and an old 200Mhz PentiumMMX lying around, I
> decided to have a go at building an optimized box without having to
> risk my regular box to the hazards that presents.
>
> To start, I've got 3 Woody pre-release CD's from Jan 3rd 2002 from a
> magazine cover DVD. I've also got sources for KDE3 BETA2, XFree864.2.0
> and the latest cvs's from XFree86 and the DRI stuff. I installed a
> base system from the Woody CD's plus all the development tools, so I
> could build the rest of the system.
>
> First things first, I built a fresh 2.4.18 kernel, since most
> improvements can be made in the system calls in the kernel.
>
> Next, I built XFree864.2.0 from the CD sources I have. I also applied
> a small patch to fix an rgb bug in the glint driver. Next I started
> building KDE3, starting with the qt libs, kde3 libs, kdebase and so
> on. Not all the modules I had would build, but thats to be expected
> from BETA.
>
> Now I know that KDE is large, it took over a full week to build
> everything that would build, running 24 hours a day, but I still think
> I could get a bit more responsivness from it.
>
> I asked my local LUG if I should consider re-building anything else to
>
> improve system response. GlibC was one recommendation I got. As I
> considered this, I stopped to think:
> Should I re-build GlibC for i586 first, and THEN build everything
> else? Also, how can I be sure that what I am building is taking
> advantage of the fact that I'm building on a 586 rather than the
> generic i386?
>
> If I understand the process, and instruction sets correctly;
> The Pentium has faster instructions that GCC can take advantage of and
>
> optimize the resulting binary.
> On the other hand, the MMX instructions require specific coding in the
>
> sources to take advantage of the improvements, and since they are
> limited to int's, not many programs bother to include MMX
> optimizations. The PIII, on the other hand, with it's SSE
> instructions, which provide MMX style optimizations for floats are
> much more useful, and XFree86 and DRI, for example have incuded
> optimizations for these.
>
> Now my understanding of the standard build process is that when I run
> ./configure in the root of the sources, it should notice that it's
> running on a i586 and set something in the make files to ensure that
> GCC optimizes for i586 when I run make. However, when I run file on a
> binary that I've build, I get:
> ELF 32-bit LSB shared object, Intel 80386, version 1 (SYSV), not
> stripped
>
> Therefore, I can't help but think I'm missing something important to
> get the best optimizations for this box.
>
> So, after all that ;-) what would be the best way to fully optimise
> this box, starting from a base install plus development stuff?
>
> Should I re-build GlibC before compiling anything else?
> Are there any other libs I should re-build?
> Should I rebuild GCC as well?
> Do I need to specify special options to ./configure to get better
> optimizations?
>
> Cheers,
>
> John Gay
Hello,
I don't want to spoil your enthusiasm but that will probably not do a
lot.
I did put gentoo on my box for the kicks and to see the wonders that
will happen once everything gets installed from source and optimised.
I didn't see anything happen there so far except for dependency problems
that remind me of rpm-hell.
Compiling is a long and resourceintensive process (I learned that) - you
better have lots of free time and lots of space on your HD on hand.
Mozilla takes about 2 hrs. and 800megs of space to compile.Don't even
think about OpenOffice and stuff like that.
And then when it crashes after about 10hrs and you get to do it all
again - now that is where the fun is!!!
Have fun,
Klaus
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