Date: Wed, 30 Nov 2005 13:30:19 +0100 From: Ulrich Spoerlein <q@galgenberg.net> To: "Daniel O'Connor" <doconnor@gsoft.com.au> Cc: Poul-Henning Kamp <phk@phk.freebsd.dk>, freebsd-current@freebsd.org, Jason Evans <jasone@canonware.com>, current@freebsd.org Subject: Re: New libc malloc patch Message-ID: <20051130123019.GA1068@galgenberg.net> In-Reply-To: <200511302252.05741.doconnor@gsoft.com.au> References: <6861.1133349506@critter.freebsd.dk> <200511302252.05741.doconnor@gsoft.com.au>
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--ZPt4rx8FFjLCG7dd Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Daniel O'Connor wrote: > On Wed, 30 Nov 2005 21:48, Poul-Henning Kamp wrote: > > In message <20051130111017.GA67032@galgenberg.net>, Ulrich Spoerlein wr= ites: > > >I just read that mmap() part and have to wonder: Is it possible to > > >introduce something like the guard pages that OpenBSD has implemented? > > >I'd love to try this out and see the dozens of applications that fail > > >due to off-by-one bugs. > > > > Guard-pages are very expensive and that is why I have not adopted > > OpenBSD's patch. Yes, of course it should be disabled as default, but if it could be implemented so you can switch at runtime or compile time (think INVARIANTS/WITNESS) *and* there is no penalty for the disabled case, that be nice. > > I would advocate that people use one of the dedicated debugging malloc > > implementations (ElectricFence ?) instead of putting too much overhead > > into our default malloc. >=20 > Electric fence is right. Although it IS slow, an order of magnitude or mo= re=20 > usually. Also if you do use it you'll probably have to bump up the=20 > vm.max_proc_mmap sysctl or it will fail to allocate memory. >=20 > Another good one is valgrind (and it detects more problems to boot :) Yes, I usualy use dmalloc and valgrind. It's sad other developers don't use any of these tools ... Ulrich Spoerlein --=20 PGP Key ID: F0DB9F44 Encrypted mail welcome! Fingerprint: F1CE D062 0CA9 ADE3 349B 2FE8 980A C6B5 F0DB 9F44 Ok, which part of "Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn." didn't you understand? --ZPt4rx8FFjLCG7dd Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2 (FreeBSD) iD8DBQFDjZtbmArGtfDbn0QRAl4bAJ9tbnYVS6dcbs0yG71W0wAqyYclfACglQEV xGjhAX6qdaQbbafU2ESQqZU= =oPSq -----END PGP SIGNATURE----- --ZPt4rx8FFjLCG7dd--
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