Date: Wed, 14 Mar 2007 21:39:09 -0800 From: Gary Kline <kline@tao.thought.org> To: Karol Kwiatkowski <karol.kwiat@gmail.com> Cc: Gary Kline <kline@tao.thought.org>, freebsd-questions@freebsd.org Subject: Re: Optimizationn questions? Message-ID: <20070315053909.GD62026@thought.org> In-Reply-To: <45F8A5BE.20704@gmail.com> References: <20070315011651.GA1524@thought.org> <45F8A5BE.20704@gmail.com>
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On Thu, Mar 15, 2007 at 02:47:42AM +0100, Karol Kwiatkowski wrote: > Gary Kline wrote: > > Two quick one for kernel and/or compiler wizards: first, is > > a 400Mz processor considered a 586 (for my KERNELCONF file)? > > That depends on processor architecture rather than clock frequency. Have > a look at dmesg output - for example, Intel Celeron 400Mhz is a 686 > class processor (I686_CPU in the kernel configuration file): > > % dmesg > % [...] > % CPU: Pentium II/Pentium II Xeon/Celeron (400.91-MHz 686-class CPU) > % [...] Dunno anything about the Xeon, but the Kayak is nuilt like a tank and has got to be == a 686 also. I'll check my dmesg too. --Until very recently, I've gone wit the default (i386??); like: how much faster is gcc tweaking going to be? I guess I'll find out! > > > Second, is it safe to do a buildworld with -O3? If there are > > stability concerns, I'll go with the default when I rebuild my > > 6.2 systems. > > If you're going to do stability/performance/compatibility tests go > ahead. In any other situation just stick with the defaults, which on > 6.2-RELEASE for my Celeron are: > > # (cd /usr/src && make -V CFLAGS ) > -O2 -fno-strict-aliasing -pipe -march=pentiumpro > > Note that '-march=pentiumpro' comes from setting 'CPUTYPE=i686' in > /etc/make.conf (examples in /usr/share/examples/etc/make.conf). Martin Tournoij pointed out what (fine-print) I didn't see [never read/very seldom read] that the world and kernel should be left at O, O2 or their default. I signal to gcc to unroll loops and know that the compiler writers are going to use their learned and practical wisdom regarding loop unrolling... . > > HTH, It has and thanks much. Gotta rebuild, but no big deal! gary > > Karol > > -- > Karol Kwiatkowski <karol.kwiat at gmail dot com> > OpenPGP 0x06E09309 > -- Gary Kline kline@thought.org www.thought.org Public Service Unix
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