Date: Thu, 7 Mar 2002 16:45:00 +0100 From: "Simon 'corecode' Schubert" <corecode@corecode.ath.cx> To: Erik Trulsson <ertr1013@student.uu.se> Cc: roam@ringlet.net, mitko@rila.bg, freebsd-hackers@FreeBSD.ORG, gclarkii@vsservices.com Subject: Re: Swapping performance Message-ID: <20020307164500.5dd21d16.corecode@corecode.ath.cx> In-Reply-To: <20020307153615.GB1942@student.uu.se> References: <20020307090707.GC26621@elvis.mu.org> <Pine.BSF.4.21.0203070359110.41354-100000@InterJet.elischer.org> <20020307142759.0d95d467.mitko@rila.bg> <20020307080906.367be8df.gclarkii@vsservices.com> <20020307164724.D377@straylight.oblivion.bg> <20020307153615.GB1942@student.uu.se>
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--=.sWC1FNHO:W3Y?f Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Thu, 7 Mar 2002 16:36:15 +0100 Erik Trulsson <ertr1013@student.uu.se> wrote: > > > > I've tested it with : > > > > > > > > cc -O6 -o malloc_test malloc_test.c > > > > > > That -O6 does not look right from here. Do we support anything over -O2? > > > > ISTR that -On is exactly the same for -O2 for n > 2; or is this stale info? > > Maybe GCC 3.x supports higher optimization levels; still, I don't think > > this would make any significant difference. > > n > 3 actually. The difference between -O2 and -O3 is that -O3 enables > inlining of functions. This usually makes the generated code larger, > and sometimes faster (and sometimes slower.) > > FreeBSD does not officially support anything above -O since there have > been reports of bad code generated when compiling with -O2 or higher. to everybody who doesn't believe that: it really generates bad code. i've been having severe problems with my tcp and udp stack lately (on a i586/mmx machine). guess what, -O2 resulted in code which >>sometimes<< generated bad tcp and/or udp checksums (depending on ip). i didn't investigate any further, but believe me: not being able to access some dns servers is a pain in the ass. cheerz corecode -- /"\ http://corecode.ath.cx/ \ / \ ASCII Ribbon Campaign / \ Against HTML Mail and News --=.sWC1FNHO:W3Y?f Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.6 (FreeBSD) iD8DBQE8h4r/r5S+dk6z85oRAqExAJ9RDOG4j8RfeZ5H/y7s5MPc9HgJaQCaAoZ3 /DAvUSN4bc0xGOzvlMnFPB8= =rHGa -----END PGP SIGNATURE----- --=.sWC1FNHO:W3Y?f-- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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