[wellylug] Sarge approaching release

[Martin Baehr]

On Fri, Sep 03, 2004 at 01:24:15PM +1200, David Antliff wrote:
> Gains from further optimisations (i686, athlon-specific,
> P4-specific, etc) are also beneficial to intensive computations.

the point is they are only beneficial to intensive computation.

> A kernel "built for your CPU" doesn't really offer much advantage for
> 'home' users - like any decent OS, Linux doesn't spend a significant
> amount of time running in the kernel, so many optimisations offer little
> improvement to a desktop PC.

that's a great point i didn't consider before, so i watched top for a
while but none of the machines i have access to have any significant
load to provide usefull numbers. all semed to have a system cpu usage of
10-20% while user cpu usage was considerably less.

> CPU-specific optimisation doesn't always provide much improvement, but in
> some areas it can be significant. Where necessary I've used apt-source to
> compile packages with my own optimisations enabled.

the trick is to know where this is. even though you are right above for
loaded machines, most users won't have a loaded machine and even then
20% cpu load for the kernel is significant enough to let optimization
matter. because everybody runs a kernel. an optimized libc and related
system libs may be good as well, because everybody uses that too. but
after that the situation is really different for every user.

> experience. I don't run Gentoo for performance reasons myself anyway, but
> I do compile everything with -march=athlon-xp -O3 -pipe, which has proven
> to be a stable combination on my hardware.

i have yet to see any numbers that show that this really speeds things up. 
and on the other hand i have seen comments that suggest that for some
applications -O3 optimizations are actually ill advised and break things.

as for me wanting to get work done, the time i would have to spend
compiling stuff would be more than the time gained from the result,
hence, i prefer to optimize user time than computer time.

greetings, martin.
-- 
looking for a job doing pike programming, sTeam/caudium/pike/roxen training,
sTeam/caudium/roxen and/or unix system administration anywhere in the world.
--
pike programmer   travelling and working in europe            open-steam.org
unix system-      bahai.or.at                       iaeste.(tuwien.ac|or).at
administrator     (stuts|black.linux-m68k).org                  is.schon.org
Martin Bähr       http://www.iaeste.or.at/~mbaehr/