Re: [gentoo-user] After gcc-3.4.6-r1 & glibc-2.4-r2 emerge!

[Boyd Stephen Smith Jr.]

On Friday 12 May 2006 06:18, Jerry McBride <mcbrides9@×××××××.net> wrote 
about 'Re: [gentoo-user] After gcc-3.4.6-r1 & glibc-2.4-r2 emerge!':
> On Thursday 11 May 2006 19:47, Richard Fish wrote:
> > On 5/11/06, Jerry McBride <mcbrides9@×××××××.net> wrote:
> > > I'm going one step further with gcc 4.1.0. After I emerged gcc and
> > > glibc... I did an "emerge -e system" twice and am now following up
> > > with two "emerge -e world" commands...
> >
> > Wow, you like to waste a lot of CPU cycles...
>
> Actually... nothing is wasted.

Actually, that's quite a BIT of waste.  There's about 30(?), maybe more 
packages in system, depending on your use flags.  About 4-5 are your 
toolchain.  So, there's 25+ compiles wasted per system pass. You *might* 
need to compile your toolchain twice, but the critical package, gcc, 
already compiles itself twice.  It compiles a minimal gcc (C-only, just 
enough to compile full gcc, and very portable across toolchains) using the 
current toochain then compiles full gcc (all your use flags settings, and 
requires gnuC extensions) using that minimal gcc.  (That's the normal gcc 
build, not Gentoo specific.)

After that, you normally only need to compile your applications ONCE.  
Cyclic dependencies could require more than one compile for full effect, 
but those are bad for other reasons, and could make it to where you have 
to recompile MORE than TWICE, depending on their complexity.

In ANY case, you don't HAVE to rebuild you applications right away, and it 
would save you a few CPU cycles to just use the new compiler new time the 
package is updated.  If you are running ~ARCH that generally pretty 
often. :)

-- 
"If there's one thing we've established over the years,
it's that the vast majority of our users don't have the slightest
clue what's best for them in terms of package stability."
-- Gentoo Developer Ciaran McCreesh