Re: [gentoo-dev] Do we want optimal performance?

[Klavs Klavsen]

Chris Gianelloni said:
[SNIP]
> Gentoo is not all about performance.  While many of our users want to
> squeeze the every drop of performance out of their systems, many use
> Gentoo for any number of other reasons such as our philosophy, our
> community, the manageability of portage, or even because they think
> Larry the Cow just owns.
>
hehe. I totally agree. I choose Gentoo for the flexibility, for instance
in getting the programversions I want to use - except I'm sad that
gcc-versions get phased out too quickly IMHO, so I can't easily choose to
stay with an "old" gcc like 3.2.2 - without running into packages I
suddenly can't upgrade automatically, because they depend on a newer GCC,
which I can see no reason for them to do.

This would ofcourse not be so big a problem, if we had proper reverse
depedencies - but like things are now - I must admit I'm afraid of
upgrading gcc/glibc on a machine in production.. have been bitten by that
one before (I always have package of the old one - but still).
[SNIP]
>
> I just want to ask where the manpower to do this will come from?  We
> would have to start over with every CPU upgrade and every toolchain
> upgrade.  It appears it would be an unending task of hours upon hours of
> labor for each package.  Have you looked at the sheer number of CFLAGS
> available?
>
You are probably right - especially when I'm told that gcc-3.5 has great
profiling capabilities (GIMPLE - whatever that is :) - which I agree would
be the better solution (so people can easily optimize their machine -
doing profiles for their usage).

>> I would suggest these tests be included like the gentoo-stats program,
>> as
>> something the individual Gentooist can choose to run after each compile
>> -
>> which would give him the optimal performance (and recompile X number of
>> times to test different flags out) on his CPU/program/GCCversion
>> combination, and at the same time, send the result to a Gentoo database.
>
> I see no problem with it provided you could find someone to actually do
> the work.  This would be *very* boring work for most, which means it
> would be abandoned by anyone but the most determined quite quickly.
>
Agreed - that's why I wanted to "throw it out there"  - so I could get
some feedback on the idea and see if it would stick.

[SNIP]
>> What do you think? am I crazy? It seems to me that the anandtech tests
>> shows that it is more than just a 1% or 2% difference, with the right
>> CFLAGS - and that the right CFLAGS for one program, can be the worst for
>> another on same CPU/GCC combination.
>
> While I agree that there can be great performance increases, I believe
> that there is a definite trade-off between performance and
> manageability.  This would be wholly unmanageable without an army of
> testers working around the clock until Gentoo ceased to be... *grin*
>
The idea would ofcourse be that, only the "obvious" programs would be
tested - but if profiling were implemented/possible with gcc-3.5 and
portage easily - I'm  fairly certain that would be of more value (would
that also help select the right CFLAGS ?)

-- 
Regards,
Klavs Klavsen, GSEC - kl@××××.dk - http://www.vsen.dk
PGP: 7E063C62/2873 188C 968E 600D D8F8  B8DA 3D3A 0B79 7E06 3C62

"Those who do not understand Unix are condemned to reinvent it, poorly."
  --Henry Spencer


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