Settings in make.conf affects compilation only?

[kbzium]

Hello,

does settings in make.conf affect compilation only or general speed of applications after it? I mean if for instance sse4 is enabled during compilation, does this software use it later alone?

Here's my config

[Gentoo64]

If your cpu supports for eg sse 4.2, then any program with the USE flag sse4_2 will take advantage of it. A lot of programs have support for things like sse etc by default with no optional use flags. As you have sse 4.2 support on your cpu then sse4_2 USE is right.
The make.conf just includes the compile time stuff which can affect the performance of the program when it's run, so the CFLAGS have an effect, and the USE removes / includes support for certain things. The main thing that would speed up compilation speed on its own is makejobs, which looks like you haven't set. Most people will use a makejobs of the number of your cpu cores, or add 1 on, so if your cpu is quad core try adding the line MAKEJOBS="-j5" to the /etc/portage/make.conf and you should compile much much faster than with default.

[kbzium]

Ok so i run into idea to compare:

my cpu spec flags:

[Gentoo64]

The USE flags are mostly not cpu related but include support for certain features. I remember what I did when I first installed Gentoo was go through the big list of USE flags and add the ones I definately want globally in my make.conf. If you use alsa and want programs to support it just add alsa to your use flags. Do that for any others, same with removing support, ie if you know you're not going to use pulseaudio then put -pulseaudio in there.

[kbzium]

I see. Last thing:

[toralf]

[dmpogo]

[wcg]

"-march=native" in CFLAGS will override things like USE="sse4_2" at compile
time. If gcc has a use for sse4_2 instructions in the code it compiles, with
"-march=native" it will check the cpu itself to see if that cpu architecture
supports the sse4_2 instructions. That goes for sets of instructions supported
by some x86 or x86_64 cpus but not others.

The USE flag will mainly affect packages like openssl, multimedia stuff,
graphics code, compression/decompression, encryption/decryption, etc,
where some package has assembler level support for those specialized
instructions that is enabled or disabled at compile time with a GNU configure
command line option (or some alternative for build trees that do not use
GNU configure). The ebuild for the package will check the USE flags and
call configure accordingly with the parameter to enable or disable that
asm code in the package that it is compiling.

If openssl is built with sse support, then it will use sse instructions every
time it runs. Whether it uses any sse4_2 instructions depends on whether
there are any in the openssl source code as well as whether the ebuild
sees the sse4_2 USE flag.

The USE flags are a Portage feature rather than a gcc feature. They are
a way to tell Portage ebuilds how to configure packages for compiling,
how to configure installation, etc.
_________________
TIA

[kbzium]

Take a look here:
https://forums.gentoo.org/viewtopic-t-861618-start-75.html

He put "march=native" in his config and he got