From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lists.gentoo.org ([140.105.134.102] helo=robin.gentoo.org) by nuthatch.gentoo.org with esmtp (Exim 4.62) (envelope-from ) id 1HajEV-0006mw-DV for garchives@archives.gentoo.org; Mon, 09 Apr 2007 02:03:51 +0000 Received: from robin.gentoo.org (localhost [127.0.0.1]) by robin.gentoo.org (8.14.0/8.14.0) with SMTP id l392292M006350; Mon, 9 Apr 2007 02:02:09 GMT Received: from mail-in-01.arcor-online.net (mail-in-01.arcor-online.net [151.189.21.41]) by robin.gentoo.org (8.14.0/8.14.0) with ESMTP id l391vB9P031917 for ; Mon, 9 Apr 2007 01:57:11 GMT Received: from mail-in-01-z2.arcor-online.net (mail-in-09-z2.arcor-online.net [151.189.8.21]) by mail-in-01.arcor-online.net (Postfix) with ESMTP id 3F3C415B827; Mon, 9 Apr 2007 03:57:09 +0200 (CEST) Received: from mail-in-13.arcor-online.net (mail-in-13.arcor-online.net [151.189.21.53]) by mail-in-01-z2.arcor-online.net (Postfix) with ESMTP id 2EEA428EF01; Mon, 9 Apr 2007 03:57:09 +0200 (CEST) Received: from [10.99.7.24] (24-75-176-5.pittpa.adelphia.net [24.75.176.5]) (Authenticated sender: dralgebra@arcor.de) by mail-in-13.arcor-online.net (Postfix) with ESMTP id EAC2422D161; Mon, 9 Apr 2007 03:57:08 +0200 (CEST) From: Sascha Hlusiak To: gentoo-user@lists.gentoo.org Subject: Re: [gentoo-user] CFLAGS "...-O3 -pipe" vs "...O2 " Date: Sun, 8 Apr 2007 21:57:03 -0400 User-Agent: KMail/1.9.6 Cc: maxim wexler References: <739325.15429.qm@web31706.mail.mud.yahoo.com> In-Reply-To: <739325.15429.qm@web31706.mail.mud.yahoo.com> Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@gentoo.org Reply-to: gentoo-user@lists.gentoo.org MIME-Version: 1.0 Content-Type: multipart/signed; boundary="nextPart3563156.QXmEvIMGyr"; protocol="application/pgp-signature"; micalg=pgp-sha1 Content-Transfer-Encoding: 7bit Message-Id: <200704082157.09565.saschahlusiak@arcor.de> X-Archives-Salt: 7e0ae164-9bbc-45f4-b143-82f5cb7e155d X-Archives-Hash: bc24803062de4e75b350f6dbb6c31f53 --nextPart3563156.QXmEvIMGyr Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline > One suggests using -O3 -pipe, the other, -O2 without > the pipe. > > How much difference does this make? Is the extra level > of optimization with pipe the equivalent of the lower > level without? =46rom the gcc manpage: =2Dpipe Use pipes rather than temporary files for communication between the various= =20 stages of compilation. This fails to work on some systems where the=20 assembler is unable to read from a pipe; but the GNU assembler has no=20 trouble. The pipe is only for speeding up the compiling process. It does not speed u= p=20 binaries.=20 The -O3 contains some more optimizations than -O2, which can result in much= =20 bigger applications and may be contraproductive. The -O2 is widely=20 recommended, but I guess you won't feel a big difference anyway. See man gc= c=20 for a more detailled description.=20 =2D Sascha --nextPart3563156.QXmEvIMGyr Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.3 (GNU/Linux) iD8DBQBGGZ11OyDtNneHFrMRAt3TAJ99z4PEF0RSxW+BDpMMuf+qMHX+FACcCxI2 ryI+7jGQb+okx4CcdbhFkSI= =f8CR -----END PGP SIGNATURE----- --nextPart3563156.QXmEvIMGyr-- -- gentoo-user@gentoo.org mailing list