Date: Mon, 10 Apr 2000 08:40:35 +0200 (SAT) From: Reinier Bezuidenhout <rbezuide@oskar.dev.nanoteq.co.za> To: kabaev@mail.ru (Alexander N. Kabaev) Cc: danfe@inet.ssc.nsu.ru, freebsd-hackers@FreeBSD.ORG Subject: Re: What are the best gcc optimization options for Pentium 200 M Message-ID: <200004100640.IAA04696@oskar.dev.nanoteq.co.za> In-Reply-To: <XFMail.000408111837.kabaev@mail.ru> from "Alexander N. Kabaev" at "Apr 8, 2000 11:18:37 am"
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Hi .. I agree that optimizations are most of the time "futile" :) .. so is resistance :) ... ina ny case .. I like to live on the edge .. that is why I'm running 5.0-current .. and I've compiled the following things with optimizations. o The whole source tree .. including my kernel o XFree86 o KDE 1.1.2 And most of the other ports I've installed ... like vmware, kdevelop etc. to name but a few ... And again ... I know I am taking a risk .. but I've been running this system for about 6 months now ... and I haven't even seen one panic or core which is "unexplained" due to bad code generation. Just once again .. YRS I know gcc generates bad code sometime and optimizations isn't the way to go ... but it works for me .. for now :) The optimizations I'm using .... In /etc/make.conf CFLAGS= -O6 -mpentiumpro -march=pentiumpro -pipe -s -fexpensive-optimizations -ffast-math COPTFLAGS= -O6 -mpentiumpro -march=pentiumpro -pipe -s -fexpensive-optimizations -ffast-math And I know -O6 is an over kill ... Bye Reinier > I doubt Mandrake gets any significant performance boost from using gcc with > optimisation levels beyond -O. They just use this "super optimised" to > stand out from all other Linux crowd rather than for any practical purpose. It > has been reported several times that optimisation levels O2 ang higher are > buggy and known to generate wrong code on several occasions. This was true for > gcc 2.7.2.3 and it is still true for gcc 2.95.2. In other words, your attempt to > squeese last drop of performance from your system in this way is futile :). The > gain you will get is just not worth associated risks. > > On 08-Apr-00 Alexey N. Dokuchaev wrote: To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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