Thread: Geeky stuff Part 1: Optimizing your compiler

Here I am gonna shows some cool flags to optimize your compiled applications for linux in faqs form.
Why compile applications?
To harvest all power of your cpu you need to compile your own package. Binaries distributed by applications like apache , mplayer , mysql, e.t.c. are not optimized for your cpu.
I have generally written here only safe configurations.



Run the command
cat /proc/cpuinfo


open /etc/make.conf
Scroll down to this:

Cflags :

march options
If you don't what is your cpu. Then use this

CFLAGS="-march=native
GCC will try to use flags appropriate for you.
If your are using core2duo or above then use this:
CFLAGS="-march=core2

Os options
O ( O for orange not 0 zero)
They vary from 0 , O1 , O2 , O3 , Os
I recommend using 02 . It determine the level of optimization. Using higher might break codes So they are not recommended. Using O = no optimization. 0s = 02 optimization with smaller binaries.

cat /proc/cpuinfo | grep flag
This command print additional flags available for use as C flags or CXX flags ( in layman terms c & c++). If you don't give out | grep flag it will print whole info about your cpu. Flags are switches for optimizing your gcc compiled codes.
Some of the flags you can use from among them are :
-msse, -msse2, -msse3, -msse4 , -mssse3,-mmmx, -m3dnow
pni= sse3
I have put -m as it should be . So now your Cflags
CFLAGS="-march=core2 -O2 -pipe -msse -msse2 -msse3 -mssse3 -mmmx"
( depending upon your arch)

-fomit-frame-pointer & -pipe
Former decreases the code size & latter increases the speed of compiling.

So now your Cflags should loook like this:
CFLAGS="-march=core2 -O2 -pipe -msse -msse2 -msse3 -mssse3 -mmmx -fomit-frame-pointer"

CXX flags
They are same as Cflags.
CXXFLAGS="${CFLAGS}"

Scroll down to
MAKEOPTS options:

They are -j2 , -j3 ,.... They should be one more than your total number of cores. If you have core2duo then
MAKEOPTS="-j3"
If you have icore 7 use this ( as it has 8 cores considering 4 virtuals + 4 real)
MAKEOPTS="-j7"

Next time we are gonna compile something. Bye.

PS: Don't plagiarize.

For more reference see GCC manual.

I know (hope most linux users know) that the kernel is not optimised for for anybody's system. If we compile the same on our system it will perform better than the pre-compiled one coming in the form of ISO or physical optical disk, etc. I have compiled linux few times to configure according to my hardware (for not including unnecessary kernel modules). But I don't feel this is recommended for everybody. Those who are familiar and are power users can do this. Others need not follow this (some resource will be wasted). Nowadays ther are people who use computer regularly but don't know about the unnecessary services working and eating up resources behind the scene still are satisfied with their need from the system.

This is what the option available to every linux (open source) user which we can never dream in M$ world.

This article change your environment variables for all things you compile.It is quite safe easy to compile your kernel & in some distro it is a default. You have to compile everything. I don't why ubuntu is warning against it. ( I have given them a new name duh-buntu). You don't need intrafs & initrd.