Optimisation

Hendrik Volker Brunn hvb at SONNE.SOLARSYSTEM
Mon Sep 4 23:21:50 PDT 2000


On Mon, Sep 04, 2000 at 05:13:09PM -0400, Chris Gianelloni wrote:
> The main problem I have is that I am not familiar with exactly *what* may be causing the problem.  I was more or less asking if there are any
> packages that anyone KNOWS offhand doesn't work at such high optimisations.  I am really wanting everything possible to be optimised.  Is it
> possible to use optimisations when compiling glibc or should I compile it with the default -O2 (maybe -O3)

I still wonder why people are trying to achieve "highest optimisation".
There is nearly no measurable improvement, and specifically none that's
worth the hassle. I don't know about pgcc, but gcc doesn't support
optimizations higher than -O3 so if you specified -O6 it'd fallback to
-O3. And that's the point I wanted to get to - it is not recommended nor
supported to compile glibc with more than -O2. And I wouldn't recommend it
for binutils, too. I for myself don't use optimisations above -O2 and I
feel fine with it. None of the packages here fails, so why should I risk
losing hair for somehting that i can't measure?

Answering your above question: Ever thought of switching off optimisations
for the failing packages? RTB!

hvb - fight back useless timeconsuming packagebreaking nervedestroying
optimisation!

If you still want to use optimisation - I recommend you do your own
research on *what* is optimized at all - if you understand these things
start calculating, if the microseconds saved on execution are worth
spending days to weeks for compiling. But please don't use optimization
without knowing what it is or what it achieves.

Sorry for this guys, but I had to say this one time, I will not comment on
opt****** any further. 8-)

-- 
Linux, of coures, cannot use such excuses because under Linux - 
"if something is possible in principle, then it is already
implemented or somebody is working on it".





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