Correct / safe cflags for core i5 3450

sale · Last edited by sale on Tue Feb 05, 2013 10:17 pm; edited 1 time in total

Hello!

I have been reading about cflags for my i5 m520 processor, but cant really decide what to put in?

I know -O2 and -pipe, but do not know about which march is proper one?

march=native or march=core2 or march=nocona

Any suggestions/help would be really apprreciated.

Thx, Sale

Anon-E-moose · Posted: Wed Mar 23, 2011 11:14 am Post subject:

What does

Veldrin · Posted: Wed Mar 23, 2011 12:15 pm Post subject:

if you are using a recent enough gcc, and do not want to use cross compile, go with -march=native
if you need cross compile, use march=core2
only use march=nocona if you have old gcc (<=4.3)

also run the command Anon-E-moose suggested - this will give you the additional options needed with march=core2 option (-sse4a and such...)

V.
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sale · Posted: Wed Mar 23, 2011 12:17 pm Post subject:

I am preparing to install, so i guess i have to find which gcc is in the install cd?

Anon-E-moose · Posted: Wed Mar 23, 2011 12:32 pm Post subject:

You could probably run a system rescue disk and find out before the install, or if it is a live cd run it first before install

But "CFLAGS="-march=native -O2 -pipe" is pretty safe.
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gcc-4.7.3 CFLAGS="-march=native -O2 -floop-interchange -floop-strip-mine -floop-block -pipe"

sale · Posted: Wed Mar 23, 2011 12:41 pm Post subject:

I think I will go with march=native.

Thx for your help to both of you.

Br, Sale

sale · Posted: Wed Mar 23, 2011 1:51 pm Post subject:

Since this proc has hyperthreading do I set makeopts -j3 or -j5?

Anon-E-moose · Posted: Wed Mar 23, 2011 1:53 pm Post subject:

sale · Posted: Wed Mar 23, 2011 2:02 pm Post subject:

Thx,

Sale

sale · Posted: Tue Feb 05, 2013 10:17 pm Post subject: CORE i5 I3450

Hi, I have ben away from Gentoo again for some time and , I have a desktop with I5 3450 proc.

Again wondering about cflags.. I have been reading this and dont really know wich ones to use..

Is GCC 4.6 now deafault or 4.3? I suppose"CFLAGS="-march=corei7 -O2 -pipe" would be O.K. or just use "march=native"?

THX, Sale

Core i7 and Core i5, Xeon 55xx

vendor_id : GenuineIntel
cpu family : 6
model : 26
model name : Intel(R) Core(TM) i7 CPU 920 @ 2.67GHz
vendor_id : GenuineIntel
cpu family : 6
model : 37
model name : Intel(R) Core(TM) i5 CPU 650 @ 3.20GHz / 660 @ 3.33 GHz
vendor_id : GenuineIntel
cpu family : 6
model : 42
model name : Intel(R) Core(TM) i5-2430M CPU @ 2.40GHz
stepping : 7
cpu MHz : 2394.550
cache size : 3072 KB
vendor_id : GenuineIntel
cpu family : 6
model : 26
model name : Intel(R) Xeon(R) CPU X5570 @ 2.93GHz
32 bit profile (x86)
CHOST="i686-pc-linux-gnu"
CFLAGS="-march=core2 -O2 -fomit-frame-pointer -pipe"
CXXFLAGS="${CFLAGS}"
64 bit profile (amd64) for < GCC 4.3
CHOST="x86_64-pc-linux-gnu"
CFLAGS="-march=nocona -O2 -pipe"
CXXFLAGS="${CFLAGS}"
64 bit profile (amd64) for GCC 4.3
CHOST="x86_64-pc-linux-gnu"
CFLAGS="-march=core2 -mtune=generic -O2 -pipe"
CXXFLAGS="${CFLAGS}"
64 bit profile (amd64) for GCC 4.6
CHOST="x86_64-pc-linux-gnu"
CFLAGS="-march=corei7 -O2 -pipe"
CXXFLAGS="${CFLAGS}"
Warning: Note that Sandy Bridge CPUs use a march and mtune of corei7-avx not corei7. See the man page for gcc.

Veldrin · Posted: Wed Feb 06, 2013 9:19 am Post subject:

toralf · Posted: Wed Feb 06, 2013 10:07 am Post subject:

sale · Posted: Wed Feb 06, 2013 9:55 pm Post subject:

THX you both for answers.

Sale