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dh003i2
Tux's lil' helper
Tux's lil' helper


Joined: 10 Mar 2003
Posts: 101
Location: Rochester, NY

PostPosted: Sat Mar 22, 2003 8:55 pm    Post subject: Ideal optimizations? Reply with quote

I've been looking at the GCC -O optimization options, and am wondering in what situations which optimizations would be best. Here's what my intuition tells me:

Kernel, Xfree86: -O3 for safe speed-enhancing optimizations

OGG, MP3, WMA, DivX-encoders, and other CPU-intensive programs (e.g., bayesian phylogeny): higher optimization levels than -O3.

WindowManager, DesktopEnvironment, office applications, and other big non-CPU intensive packages: -Os to reduce HD-usage and RAM-usage.

Opinions?
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bsolar
Bodhisattva
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Joined: 12 Jan 2003
Posts: 2764

PostPosted: Sat Mar 22, 2003 9:11 pm    Post subject: Re: Ideal optimizations? Reply with quote

dh003i2 wrote:
I've been looking at the GCC -O optimization options, and am wondering in what situations which optimizations would be best. Here's what my intuition tells me:

Kernel, Xfree86: -O3 for safe speed-enhancing optimizations

The kernel uses is own set of flags that overrides make.conf.

Quote:
OGG, MP3, WMA, DivX-encoders, and other CPU-intensive programs (e.g., bayesian phylogeny): higher optimization levels than -O3.

There are no optimization levels higher than -O3.

Quote:
WindowManager, DesktopEnvironment, office applications, and other big non-CPU intensive packages: -Os to reduce HD-usage and RAM-usage.

Makes sense (I use -Os for everything).

Quote:
Opinions?

Remember that the speed gain from -O2 to -O3 is not that much, barely noticeable if noticeable at all IMHO. Also some packages override your settings because they want a particular set of flags.
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