Variables and flags that can be use in makepkg.conf

srivo · 2010-10-28 10:18:56

Hello,

I didn't find a lot of information on the wiki about variable that can be use to optimize the code for a specific machine. Can we use the same variable than the make.conf in Gentoo like:

VIDEO_CARDS="nvidia"

LINGUAS="en fr en_CA fr_CA" 

USE="..."

Thanks

Allan · 2010-10-28 10:51:51

Read "man makepkg.conf" to see a list of what you can use... Apart from CFLAGS, LDFLAGS... you won't see USE flags because we are not Gentoo.

srivo · 2010-10-29 22:17:41

Thank Allen!

This answer my question. I just want to be sure I know all the parameter to optimize the compiler. I prefer Arch to Gentoo anyway!

But by the way. Is there real performance improvement if I build package for my specific machine or the build function is more useful to compile stuff from AUR or to modified program in the ABS tree?

Allan · 2010-10-29 22:29:02

Depends on your system... At the most I would rebuild the kernel and software for video encoding. Otherwise you will not gain back the time spent compiling your "optimized" versions...

ChoK · 2010-10-30 08:01:51

In video encoding, most of the CPU intensive tasks are written in assembler (in x264 atleast) so you will not gain anything.

The biggest compilation gains (in compilation speed and application speed) are -pipe -O2 -fomit-frame-pointer and -mfpmath=sse. (I omit unsafe flags like -ffast-math)
-fomit-frame-pointer and -mfpmath=sse are default for x86-64
-02 and -pipe are default in Arch

The rest of options may speed up your system (-march=native for example) but you are looking at 5%, maybe 15% on very specific applications, and it's sometimes very costly in binary size and compilation time (-O3 for example). There are many benchmarks available of different compiler optimizations but Arch's default options are sane and sound.

You may also be interested in LDFLAGS so your apps start faster and feels more responsive.

If compilation sparks your interest, you may be interested in gcc's graphite framework and also the Link Time Optimization (LTO).

Last edited by ChoK (2010-10-30 08:17:38)

srivo · 2010-10-30 23:49:41

Thanks guys,

I'm building my first Arch kernel and making a lot of experiment to look at performance improvement!

Arch Linux

#1 2010-10-28 10:18:56

Variables and flags that can be use in makepkg.conf

#2 2010-10-28 10:51:51

Re: Variables and flags that can be use in makepkg.conf

#3 2010-10-29 22:17:41

Re: Variables and flags that can be use in makepkg.conf

#4 2010-10-29 22:29:02

Re: Variables and flags that can be use in makepkg.conf

#5 2010-10-30 08:01:51

Re: Variables and flags that can be use in makepkg.conf

#6 2010-10-30 23:49:41

Re: Variables and flags that can be use in makepkg.conf

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