Date: Wed, 25 May 2005 15:38:11 -0700 From: Kris Kennaway <kris@obsecurity.org> To: Jon Dama <jd@ugcs.caltech.edu> Cc: Bjarne Wichmann Petersen <freebsd.nospam@mekanix.dk>, Mike Jakubik <mikej@rogers.com>, Matthias Buelow <mkb@incubus.de>, freebsd-stable@freebsd.org, Kris Kennaway <kris@obsecurity.org> Subject: Re: Performance of 4.x vs 5.x (Re: Lifetime of FreeBSD branches) Message-ID: <20050525223811.GA58132@xor.obsecurity.org> In-Reply-To: <Pine.LNX.4.53.0505251520530.5486@riyal.ugcs.caltech.edu> References: <3248.172.16.0.199.1116876092.squirrel@172.16.0.1> <200505252342.01938.freebsd.nospam@mekanix.dk> <20050525214555.GA41695@xor.obsecurity.org> <200505260014.37054.freebsd.nospam@mekanix.dk> <Pine.LNX.4.53.0505251520530.5486@riyal.ugcs.caltech.edu>
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--17pEHd4RhPHOinZp Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, May 25, 2005 at 03:33:39PM -0700, Jon Dama wrote: > Could this be quantified by setting up a synthetic experiement: >=20 > 1) one machine uses dummynet to generate a uniform packet/sec stream > 2) another machine has a process receiving those packets and recording > their arrival relative to the local TSC. afaik, the TSC is the only > source of wall-time that doesn't involve a system call. Is that right? > Are the TSCs synchronized on SMP systems? > 3) Generate another source of activity on the receiving machine to > estimate the effect of PREEMPTION relative to the (lack of) quiescence. > 4) use the jitter in the TSC deltas to infer the effect of preemption That would be attempting to benchmark something entirely different. Kris --17pEHd4RhPHOinZp Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.1 (FreeBSD) iD8DBQFClP5SWry0BWjoQKURAp6GAKDoOZ07qa65lxWmROgf8yzQ0fpvNgCfRnG7 wyuKi94dv0udUQyHH8YNAXE= =wJ0Y -----END PGP SIGNATURE----- --17pEHd4RhPHOinZp--
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