Date: Fri, 22 Sep 2000 09:58:28 -0500 From: Glenn Johnson <gjohnson@nola.srrc.usda.gov> To: "S. David Pullara" <sdpullara@telus.net>, freebsd-questions@FreeBSD.ORG Subject: Re: Intel cpu's and the -march switch Message-ID: <20000922095828.A4861@node1.cluster.srrc.usda.gov> In-Reply-To: <20000922095644.A43762@indocyber.com>; from john@indocyber.com on Fri, Sep 22, 2000 at 09:56:44AM %2B0700 References: <14794.8801.494001.718949@yuggoth.warpedspace.org> <20000921134425.A91788@node1.cluster.srrc.usda.gov> <20000922095644.A43762@indocyber.com>
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On Fri, Sep 22, 2000 at 09:56:44AM +0700, John Indra wrote: > On Thu, Sep 21, 2000 at 01:44:25PM -0500, Glenn Johnson wrote: > > |You will not notice any perceptible performance improvement but > |you may notice your kernel and/or programs acting strangely after > |compiling with those options. I would recommend that you _not_ bother > |with the -march or -mcpu options. > > How strange? The keyword was _may_ in "may notice". In any event it has been stated very clearly on the mailing lists that if you use optimizations above the default -O and something is not working correctly that you are on your own. > I've been having this /etc/make.conf entry on my personal workstation > since the day FreeBSD 4.1-RELEASE (now, it's FreeBSD 4.1-STABLE) was > out: > > CFLAGS= -O6 -march=pentiumpro -funroll-loops -fstrength-reduce -ffast-math -fexpensive-optimizations -fomit-frame-pointer -pipe > COPTFLAGS= -O6 -march=pentiumpro -funroll-loops -fstrength-reduce -ffast-math -fexpensive-optimizations -fomit-frame-pointer -pipe > CXXFLAGS+= -fmemoize-lookups -fsave-memoized > > This is not my production machine, only the machine I used daily as: > web servers, proxy, firewall&NAT, mail server, DNS, and I use GIMP and > XMMS a lot. In working hours, my baby is ``tortured'' really bad, a > lot of request from approximately 40 other Windows based PC. It's a > Compaq Deskpro with Pentium III 500 MHz and 256 MB of RAM. > > Days of uptime, without any unintentional reboots, and my feeling > tells me that with those optimization, my machine runs faster :))) The original question was with regards to the -march or -mcpu flags specifically. You have gone way beyond that in your optimizations. The -fomit-frame-pointer flag will definitely give a boost in performance and should not cause any problems except with debugging. I gave my recommendation based on the specifics of the question but after all it was just a recommendation. -- Glenn Johnson USDA, ARS, SRRC Phone: (504) 286-4252 New Orleans, LA 70124 e-mail: gjohnson@nola.srrc.usda.gov To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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