On Fri, Dec 15, 2006 at 07:14:53PM +0100, Stefan Ehmann wrote: > > CPU: AMD Athlon(TM) XP 2700+ (2166.44-MHz 686-class CPU) .. > Settings/Compiler | gcc-3.4 | gcc-4.1 | gcc-4.2 > ----------------------------+---------+---------+--------- > -O2 | 6.46s | 6.67s | 6.38s > -O2 -funroll-loops | 4.44s | 4.16s | 4.02s > -O2 -march=athlon-xp -fun.. | 4.39s | 4.38s | 4.26s > -O3 | 6.14s | 5.23s | 5.16s > -O3 -funroll-loops | 4.24s | 4.87s | 4.95s > -O3 -march=athlon-xp -fun.. | 4.19s | 4.90s | 5.07s A fine example that -O3 isn't always better than -O2. I wonder if you're blowing the L2 cache. IIRC, all Athlon XP 2700+ are the Thoughbread core, which has only 256KB L2. -- -- David (obrien_at_FreeBSD.org)Received on Fri Dec 15 2006 - 19:52:07 UTC
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