[Sussex] Online with Ubuntu

[Steve Dobson]

Chris, Geoff, and all

On Tue, Feb 08, 2005 at 06:40:33PM -0000, Chris Jones wrote:
> On Tue, February 8, 2005 12:18, Geoffrey Teale said:
> > Yes, but see above.  Doing it on debian would be as much work as doing
> > LFS if not more.  Just because you can do something with Debian it
> 
> Not really, you could rebuild all the packages with some pretty simple
> scripting and CFLAGS playing.
> 
> > Ever wonder why chip manufacturers bother to create things like MMX or
> > 3Dnow?
> 
> For accelerating specific operations, typically floating point type
> operations. MMX/3DNow are only of any real use if you are hand coding
> assembly routines with them for things like codecs or 3D work. gcc isn't
> going to be able to do anything significant with them on most code.
> 
> > skilled hands a system compiled from scratch with the right flags can
> > have significant performance gains against the same box.
> 
> Do you have numbers? I've seen a lot of gentoo people claim a lot of
> things that nobody has managed to back up with actual data. Outside of the
> kernel and libc most things are going to be highly transport bound and all
> the optimistion in the world won't make your disks go any faster ;)
> 
> It's also worth noting here that Ubuntu's packages are not built for 386
> CPUs, they are built with P4 instructions, which, if anything will make
> the most difference when it comes to gcc flags.

Performance isn't everything.  Your time spent in front of the system is
far more important.  There are very few parts of the system that need
to be compiled to their absolute limit for maximum performance.

Most applications do not need all of the time alloted to them before they
need to get/dend data from/to disk, LAN, or some where that is slow and
will take far to long (in CPU terms).  In such cases the applications stops
running and waits for the kernel to get/put the data from the appropriate
device.  Unless your computer has some other computations to do (like
calculate pi or SETI) it will run the idle task.  The idle task is just
there to soak up any unneeded CPU cycles.

My laptop is a 1.2GHz system that supports CPU freq scaling.  I've 
enabled it ('cos it is their).  Most of the time it runs in slow mode
and I really don't notice the difference.  About the only time I see it
kick in is when I start a POVRay render.

If you pick a distro because it is "faster" then one of the others you
better not be wasting all those extra CPU cycles you are getting doing
silly things.

I believe that to get the "maximum" performance from Gentoo you need 
to compile everything.  Pre-compiled binaries are always a compromise
so they can run on a wide number of hardware configurations,  but 
these are optimised binaries, just not the best optimised for any 
given system.  It took Geoff once (IIRC) three days to do a full level
compilations of his Gentoo system (twin processes) thats 72 hours real
time, and couldn't use the system while doing that.

While he was doing that I did a big package upgrade on my (single
processor) laptop - three hours.  Now I run a local Debian mirror
that time is down to less than an hour.  That is almost no downtime
at all!

I'm not saying here "don't use Gentoo", far from it.  I'm just saying
know what features in a distro are the ones that provide you with the
most benefit, and selected your distro accordingly.

I use Debian because it provides the lowest admin costs of any distro
I've tried.  It does things right.  Debian has a well defined set of
standards for how packages are to be built.  That helps me, it makes
it very easy for me to find the config files, data files, etc (even
for a package I have never used before).  I save time.  In the past
year my four main systems (firewall, DMZ server, LAN server, and laptop)
have cost me no more the three days sys admin time.  That is why I
like Debian.  Performace is secondary.

Steve