Date: Sat, 13 May 2006 11:58:26 -0400 From: Kris Kennaway <kris@obsecurity.org> To: "Matthew D. Fuller" <fullermd@over-yonder.net> Cc: freebsd-stable@FreeBSD.org, Kris Kennaway <kris@obsecurity.org> Subject: Re: INVARIANTS (was Re: RELENG_4 -> 5 -> 6: significant performance regression) Message-ID: <20060513155826.GA47324@xor.obsecurity.org> In-Reply-To: <20060513155232.GF3874@over-yonder.net> References: <20060427160536.M96305@atlantis.atlantis.dp.ua> <20060427181226.GA66431@xor.obsecurity.org> <20060428122448.K57436@atlantis.atlantis.dp.ua> <20060428182818.GA10410@xor.obsecurity.org> <20060512161836.R75964@atlantis.atlantis.dp.ua> <20060513020051.GB18438@xor.obsecurity.org> <20060513084236.W74146@atlantis.atlantis.dp.ua> <20060513143740.GA46313@xor.obsecurity.org> <20060513155232.GF3874@over-yonder.net>
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--NzB8fVQJ5HfG6fxh Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sat, May 13, 2006 at 10:52:32AM -0500, Matthew D. Fuller wrote: > On Sat, May 13, 2006 at 10:37:40AM -0400 I heard the voice of > Kris Kennaway, and lo! it spake thus: > >=20 > > With respect to INVARIANTS, you just need to get used to the fact > > that running thousands of checks for bugs is incompatible with > > running at optimal speed. >=20 > (I'm not sure what the point of saying this is, really, but I'll say > it anyway.) >=20 > I've run all my systems with INVARIANTS for at least as long as I've > known it was there. While more performance is always good, hardly any > of my systems are so constrained as to need every bit of suds all the > time; trading off a bit of performance for a better chance of catching > a problem before it really screws something up is just a no-brainer. >=20 > Additionally (and especially on -CURRENT), I run it because I think > more people run it than don't, and while theoretically it should just > add checks, I know there are places where it changes code paths much > more than that. So, the !(INVARIANTS) code paths don't get exercised > as much, and I worry about bugs hiding there that don't get found (I > think I recall a case or three over the years of just that happening). > Like everyone, I'm sure, I'm all for ferreting out bugs and getting > them fixed, but I'd rather not have to bust my virtual face on the > virtual concrete to do it ;) FYI, INVARIANTS adds checks but does not (is not supposed to) divert code paths. Kris --NzB8fVQJ5HfG6fxh Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.3 (FreeBSD) iD8DBQFEZgIhWry0BWjoQKURAgo5AKDv4ciz2X7h3T+u4c6g08Jdj5E3/ACglaEe bw4on7MHL305iVOE4fcBxhE= =DTVD -----END PGP SIGNATURE----- --NzB8fVQJ5HfG6fxh--
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