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- <li><em>date</em>: Thu Feb 12 07:55:20 2004</li>
- <li><em>from</em>: bjorn at sccs.swarthmore.edu (Bjorn Dittmer-Roche)</li>
- <li><em>in-reply-to</em>: <1076557459.3920.828.camel@localhost></li>
- <li><em>references</em>: <<a href="msg00388.html">[email protected]</a>> <<a href="msg00404.html">[email protected]</a>> <1076557029.30236.818.camel@localhost> <1076557459.3920.828.camel@localhost></li>
- <li><em>subject</em>: -O3 vs. -O2 (was Re: [ale] sharing an experience....debian....)</li>
> There's another reason why I ask. I frequently install Gentoo on slow
> machines because a) I want to wring every last bit of performance I can
> out of the hardware available and b) I'm not under time pressure to do
> so :)
>
> But, according to this, in doing so and accepting the -O3 optimization
> suggested, I may only be hurting myself, ESPECIALLY if after building
> gcc, glibc, etc. in the bootstrap phase with -O3 and subsequently
> compiling everything else with that gcc, it might be taking m hours
> (days?) longer than necessary.
I don't have a good answer to this, but in my own tests of -O2 vs. -O3
with some complex C++ code I got a HUGE improvement with -O3, so now I
alays use it. On the advice of other suggestions on this list, I might try
the -fnounroll-loops, though. It's also possible that more optimization
works better with C++.
bjorn
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<ul><li><strong>References</strong>:
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<li><strong><a name="00388" href="msg00388.html">[ale] sharing an experience....debian....</a></strong>
<ul><li><em>From:</em> keith at iqtv.com (Keith Morris - IQ)</li></ul></li>
<li><strong><a name="00404" href="msg00404.html">[ale] sharing an experience....debian....</a></strong>
<ul><li><em>From:</em> james at sumners.ath.cx (James Sumners)</li></ul></li>
<li><strong><a name="00412" href="msg00412.html">-O3 vs. -O2 (was Re: [ale] sharing an experience....debian....)</a></strong>
<ul><li><em>From:</em> hbbs at comcast.net (Jeff Hubbs)</li></ul></li>
<li><strong><a name="00413" href="msg00413.html">-O3 vs. -O2 (was Re: [ale] sharing an experience....debian....)</a></strong>
<ul><li><em>From:</em> hbbs at comcast.net (Jeff Hubbs)</li></ul></li>
</ul></li></ul>
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