Date: Fri, 15 Dec 2006 12:51:38 -0800 From: "David O'Brien" <obrien@freebsd.org> To: Stefan Ehmann <shoesoft@gmx.net> Cc: Peter Jeremy <peterjeremy@optushome.com.au>, freebsd-current@freebsd.org, Steve Kargl <sgk@troutmask.apl.washington.edu> Subject: Re: Let's use gcc-4.2, not 4.1 -- OpenMP Message-ID: <20061215205138.GB55276@dragon.NUXI.org> In-Reply-To: <200612151914.53705.shoesoft@gmx.net> References: <20061213192150.CF83D16A417@hub.freebsd.org> <458235EC.80300@samsco.org> <200612151250.10033.shoesoft@gmx.net> <200612151914.53705.shoesoft@gmx.net>
next in thread | previous in thread | raw e-mail | index | archive | help
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@FreeBSD.org)
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20061215205138.GB55276>