Date: Mon, 14 Nov 2005 18:07:55 +0100 From: Roland Smith <rsmith@xs4all.nl> To: freebsd-questions@freebsd.org Subject: Re: Makefile and Kernel Optimizations in 6.0 Message-ID: <20051114170755.GB48916@slackbox.xs4all.nl> In-Reply-To: <20051114102308.7515.GERARD@seibercom.net> References: <20051114102308.7515.GERARD@seibercom.net>
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--z6Eq5LdranGa6ru8 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Nov 14, 2005 at 10:23:22AM -0500, Gerard Seibert wrote: > I have read on this forum that the /etc/make.conf file has been moved in > version 6.0. I assume that although it has been moved, that it still > serves the same purpose as it did in the 5.4 version. Is that correct? It hasn't been moved. It's still /etc/make.conf. The names of some variables have changed from NOFOO to NO_FOO. > I also read somewhere that version 6 has CFLAGS=3DO2 set by default. Does > it also have COPTFLAGS=3D-O2 set or does it make any difference? I didn't notice the difference on a 2.4 GHz amd64. >=20 > Makeoptions COPTFLAGS=3D"O2 - pipe" Actually it goes on to recommend > '-funroll-loops' and '-ffast-math' as well. Since I do not know what > those two are about, I never used them. In any case, is it recommended > to use any optimization in the kernel in the new 6.0 version? You can have it in the config file or in make.conf, both work. I don't think that the kernel uses floating point, so -ffast-math shouldn't make a lot of difference. The -pipe flag speeds up the compilation somewhat, but has no effect on the generated code. The -funroll-loops replaces loops of which the size is known by serial instructions. This is somewhat faster but generates larger binaries. Complete information about what an option does is available in the info file of gcc. You can type 'info gcc' to read it, or use the info reader built into emacs. Unless you have an app that takes hours or days to run, I wouldn't worry about optimization settings. Roland --=20 R.F.Smith (http://www.xs4all.nl/~rsmith/) Please send e-mail as plain text. public key: http://www.xs4all.nl/~rsmith/pubkey.txt --z6Eq5LdranGa6ru8 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2 (FreeBSD) iD8DBQFDeMRrEnfvsMMhpyURAl0JAKCryrJloIeMHWUZlKa1PPGjAQPLcgCgiPV9 hP/KLZo508xXDRlrev/DS1c= =65GT -----END PGP SIGNATURE----- --z6Eq5LdranGa6ru8--
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