[GRLUG] FOR SALE - 16-Cores, 128GB RAM, 3.2TB, RAID, 2xFX4500 Graphics

[Michael Mol]

On Sat, Jul 25, 2009 at 12:20 AM, Bob Kline<bob.kline at gmail.com> wrote:
> OK.  I've never used Gentoo, but
> thought one of the motivations for
> doing so was that you compiled it
> for your specific processor, and got
> some kind of performance bump.

This is definitely true; Most distros are compiled targeting i686--The
Pentium Pro capabilities that have been around since the 90s.
However, individual programs which can take special benefit from it
(mostly multimedia applications) get packaged with routines compiled
for CPU features that are detected at run-time.  That is, if the
developers of the program see the performance gain worth the extra
effort.  In most cases, it's not worth it to the individual program's
developers to do that.

On the other hand, when you have a whole bunch of layered libraries
providing abstraction and abstraction, where each isn't efficiently
using your processor, and it adds up.

>
> I do use Ubuntu, and upgrades of one
> sort or another come along regularly.
> But the packages are generic, and all
> one sees is "i386" or some kind of 64-bit
> package, and doesn't get whatever
> optimization might occur by compiling
> for your exact CPU.

Ubuntu significantly changes underlying infrastructure every six
months, which means that any configuration or personalization tweaks
you've done stand a good risk of breaking when you upgrade.

See my remarks on per-package optimizations.  For most folks though,
using a 64-bit distro is an excellent idea, even if you don't need
"support" for more than 4GB of RAM; All 64-bit x86 processors have a
common baseline of features, including mmx, sse and sse2, IIRC.  Not
to mention a greater number of GPRs.  The fear of data bloat isn't
really accurate, as it only necessarily applies to pointer types.  The
net result?  It'll still run more efficiently.

>
> One can of course download tar-balls,
> and build and install them to get the
> latest of something.  I used to do this
> with GNU packages, but it just doesn't
> seem worth the bother any more unless
> it's for serious bug fixes.  But Ubuntu
> does that anyway.  Maybe a short while
> later.

I got tired of grabbing tarballs and recompiling so I could find and fix bugs.

>
> That I can see, if one wants more
> performance, buy higher performance
> hardware.

Maybe my time isn't as valuable as yours, but I'm willing to spend
time to avoid spending money.  That's the same reason I did my own
auto maintenance with my last car.

> Even trying to optimize
> compile code can only take one a little
> ways in terms of performance increases.

While I don't believe there's such a thing as a valid benchmark in
such cases, I do understand enough of the low level details to
recognize that there is a gain on aggregate.

> That I can tell, the other reason for
> upgrading is usually bug fixes, and, more
> rarely, improved features.

Bug fixes are extremely important.  Some will be security related,
others simply make things work the way you want them to work. (Such as
when I dug into MediaTomb, found my way into ffmpeg, and ultimately in
the bowels of libavcodec.)


-- 
:wq