| 1 |
Hi all.. |
| 2 |
|
| 3 |
I think what -O3 is not _dangerous_ when you know how to use, a few posts |
| 4 |
ago someone mentioned not all of packages can be compiled using -O3, if I am |
| 5 |
not wrong was GCC and OpenOffice.org. |
| 6 |
|
| 7 |
The thing is: -O3 is not a _damage_ is an carefully flag to compile for some |
| 8 |
packages.. |
| 9 |
|
| 10 |
In some webpages I people said : ".. -O3 is not used by developer because |
| 11 |
come troubles when you want to do a debug..". |
| 12 |
|
| 13 |
But: |
| 14 |
http://www.nersc.gov/vendor_docs/intel/f_ug2/dbg_opt.htm, |
| 15 |
http://linuxgazette.net/121/hegde.html, |
| 16 |
http://publib.boulder.ibm.com/infocenter/macxhelp/v6v81/index.jsp?topic=/com.ibm.xlf81m.doc/pgs/ug42.htm |
| 17 |
. |
| 18 |
|
| 19 |
"...The following setting is the "Optimizations". You shouldn't use O3 as it |
| 20 |
takes longer to compile, the generated code will be sometimes faster, |
| 21 |
sometimes slower and almost always larger. For example, a program that was |
| 22 |
compiled with the O2 level of optimization is 250KB large and is quite fast, |
| 23 |
the same program compiled with the O3 level of optimization can take more |
| 24 |
time to compile, produce a larger binary, depending on the code, even |
| 25 |
500-700KB large and it can be slower or faster. Therefore, the O3 |
| 26 |
optimization level isn't recommended. Use O2 if you need the best |
| 27 |
optimization without adding the risk of obtaining large binaries, which need |
| 28 |
a long time to be loaded before being executed and are not always faster..." |
| 29 |
take of http://www.softpedia.com/reviews/linux/Gentoo-Review-20543.shtml. |
| 30 |
|
| 31 |
|
| 32 |
On 4/11/07, Bo Ørsted Andresen <bo.andresen@××××.dk> wrote: |
| 33 |
> |
| 34 |
> On Wednesday 11 April 2007 12:56:43 Daniel Iliev wrote: |
| 35 |
> > Sorry, I don't get it. Perhaps it is my poor English but I couldn't |
| 36 |
> > understand two things: |
| 37 |
> > - Is -O3 supported by Gentoo or not? |
| 38 |
> |
| 39 |
> -O3 is supported by Gentoo. |
| 40 |
> |
| 41 |
> > - What's the special thing about Gentoo ebuilds that makes -O3 |
| 42 |
> dangerous? |
| 43 |
> |
| 44 |
> No no. The special thing about Gentoo ebuilds is that -O3 in make.conf is |
| 45 |
> safe |
| 46 |
> for all packages because those packages for which -O3 isn't safe are |
| 47 |
> replacing it with -O2 in the ebuilds (or eclasses). |
| 48 |
> |
| 49 |
> -- |
| 50 |
> Bo Andresen |
| 51 |
> |
| 52 |
> |
| 53 |
|
| 54 |
|
| 55 |
-- |
| 56 |
['Cause without love I won't survive, I love you]. I |
| 57 |
|
| 58 |
Francisco Rivas |
| 59 |
2.6.19-gentoo-r5 x86 |
| 60 |
udev v087 gnome 2.16.2 |
| 61 |
xorg-x11-7.1 hotplug v20040923-r2 |
| 62 |
e-mail : fjrivas@××××××.ve |
| 63 |
msn : taken2k4@×××××.com |
| 64 |
|
| 65 |
-----BEGIN GEEK CODE BLOCK----- |
| 66 |
Version: 3.1 |
| 67 |
GCS/E/IT/MU d-(+)@ s++: a-- C++++>++++ ULSC*()>+++ P+(++)>+++ L++(+++)>++++ |
| 68 |
!E--- W+>++ !N* !o-(--)>-- K--? !w--- !O !M !V PS@ !PE@ Y> PGP t 5 X R+>+ |
| 69 |
tv- b DI D G e++>+++ h-> r++>+++ y- |
| 70 |
------END GEEK CODE BLOCK------ |
Archives