[gentoo-dev] -O2 <=> -O3 ?

[gentoo-dev] -O2 <=> -O3 ?

[Bart Verwilst]

I read on the KDE mailing list the following statement:


<snip>
-O3 is a bit slower than -O2 since it does extra optimizations.  If you've 
got a slow box (like me, K6 III 400) you might want to forgo -O3 and use 
regular -O2.
</snip>

I'm on a K6 III 400, if i change the -O3 to -O2 in my /etc/make.conf , will 
my system go faster? I noticed that KDE runs a little slower than on my 
Redhat 7.1....  Please give me your thoughts?

Thanks!

Bart

PS is cvs.gentoo.org down? emerge rsync isn't working the whole day now....

RE: [gentoo-dev] -O2 <=> -O3 ?

[Erik Van Reeth]

Hi

> I'm on a K6 III 400, if i change the -O3 to -O2 in my
> /etc/make.conf , will
> my system go faster? I noticed that KDE runs a little slower than on my
> Redhat 7.1....  Please give me your thoughts?

I think this is due because the 'objprelink' USE flag is not active by
default
(commented out in /etc/make.conf). This setting gives faster code.


Erik

Re: [gentoo-dev] -O2 <=> -O3 ?

[Blue Lizard]

Erik Van Reeth wrote:
> Hi
> 
> 
>>I'm on a K6 III 400, if i change the -O3 to -O2 in my
>>/etc/make.conf , will
>>my system go faster? I noticed that KDE runs a little slower than on my
>>Redhat 7.1....  Please give me your thoughts?
>>
> 
> I think this is due because the 'objprelink' USE flag is not active by
> default
> (commented out in /etc/make.conf). This setting gives faster code.
> 
> 
> Erik
> 
> 
> _______________________________________________
> gentoo-dev mailing list
> gentoo-dev@cvs.gentoo.org
> http://cvs.gentoo.org/mailman/listinfo/gentoo-dev
> 
> 

to bart: i believe they refer to -O2 being faster COMPILE, as -O3 is 
higher optimization for speed and larger code size and longer compile 
time etc.  There are some fine tunings you can do to make the most out 
of your time and space in all areas.  check out the gcc documentation on 
options that control optimization.  For instance, specifying what kinds 
of functions to inline.

to erik: i thought 7.1 does not use objprelink?  it wasnt exactly stable...

Re: [gentoo-dev] -O2 <=> -O3 ?

[Bart Verwilst]

objprelink doesn't give me a faster kde, it slows down my kde from 
for example konqueror in 2 secs to a 5 second or more startup time.
I've compiled different systems with and without prelinking, and the 
systems without prelinking are _always_ much faster than the ones with 
it.. But now my (non-prelinked) kde seems A LOT slower than my 
standard redhat 7.1 kde.... Does anyone has any ideas why that's so?
Gentoo should be totally optimised to my machine..?

Thanks!

Bart Verwilst

----- Original Message ----- 
From: "Erik Van Reeth" <erik@vanreeth.org>
To: <gentoo-dev@cvs.gentoo.org>
Sent: Sunday, September 23, 2001 11:46 PM
Subject: RE: [gentoo-dev] -O2 <=> -O3 ?


> Hi
> 
> > I'm on a K6 III 400, if i change the -O3 to -O2 in my
> > /etc/make.conf , will
> > my system go faster? I noticed that KDE runs a little slower than on my
> > Redhat 7.1....  Please give me your thoughts?
> 
> I think this is due because the 'objprelink' USE flag is not active by
> default
> (commented out in /etc/make.conf). This setting gives faster code.
> 
> 
> Erik
> 
> 
> _______________________________________________
> gentoo-dev mailing list
> gentoo-dev@cvs.gentoo.org
> http://cvs.gentoo.org/mailman/listinfo/gentoo-dev
>