Date: Sun, 17 Dec 2006 15:44:25 +0100 From: Ulrich Spoerlein <uspoerlein@gmail.com> To: obrien@freebsd.org, Stefan Ehmann <shoesoft@gmx.net>, freebsd-current@freebsd.org, Peter Jeremy <peterjeremy@optushome.com.au>, Steve Kargl <sgk@troutmask.apl.washington.edu> Subject: Re: Let's use gcc-4.2, not 4.1 -- OpenMP Message-ID: <20061217144425.GA1463@roadrunner.aventurien.local> In-Reply-To: <20061215205138.GB55276@dragon.NUXI.org> References: <20061213192150.CF83D16A417@hub.freebsd.org> <458235EC.80300@samsco.org> <200612151250.10033.shoesoft@gmx.net> <200612151914.53705.shoesoft@gmx.net> <20061215205138.GB55276@dragon.NUXI.org>
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David O'Brien wrote: > 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. I'd be very much interested in -Os numbers. It should help with the cache ... Ulrich Spoerlein -- A: Yes. >Q: Are you sure? > >A: Because it reverses the logical flow of conversation. > >>Q: Why is top posting frowned upon?
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