From owner-freebsd-hackers Wed Nov 13 20:48:46 2002 Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id B3A1137B401 for ; Wed, 13 Nov 2002 20:48:45 -0800 (PST) Received: from web.internal.psiu.dyndns.org (alb-24-58-129-23.nycap.rr.com [24.58.129.23]) by mx1.FreeBSD.org (Postfix) with ESMTP id E4D9643E42 for ; Wed, 13 Nov 2002 20:48:44 -0800 (PST) (envelope-from dolemite@psiu.dyndns.org) Received: from ultraalex.psiu.dyndns.org ([10.2.2.101]) by web.internal.psiu.dyndns.org (8.12.6/8.12.5) with ESMTP id gAE4nttC056878 for ; Wed, 13 Nov 2002 23:49:55 -0500 (EST) (envelope-from dolemite@psiu.dyndns.org) Received: (from dolemite@localhost) by ultraalex.psiu.dyndns.org (8.11.6+Sun/8.11.6) id gAE4mVo00231 for freebsd-hackers@freebsd.org; Wed, 13 Nov 2002 23:48:31 -0500 (EST) Date: Wed, 13 Nov 2002 23:48:31 -0500 From: Alex Newman To: freebsd-hackers@freebsd.org Subject: tcp randomness Message-ID: <20021114044831.GA17762@ultraalex.psiu.dyndns.org> Reply-To: dolemite@wuli.nu Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.4i Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG So i am doing an experiment which adds a random delay to tcp flows to achieve alot of the same stuff you get with RED and was planning on testing it with a divert socket. The problem is sometimes this involves adding a delay of say 2 ms for instance. Is this even possible on intel hardware. I know that thier is almost no way to get ethernet to be that accurate (I don't know about device polling maybe that will do it) but i think adding this delay to outgoing packets before it hits the card should add the entropy i am looking for. I have a couple of questions: 1) How much delay will i encour by passing the packet out through ipfw to a divert socket? 2) Does changing the HZ rate in the kernel actually cause ints to happen faster? Will this help me? -- Alex Newman Passant, comme toi j'ai passe`. dolemite@wuli.nu Le fleuve est revenu se perdre dans sa source. www.wuli.nu/users/dolemite Fais silence; assieds-toi sur ce marbre brise`. Pose un instant le poids qui fatigue ta course; J'eus de me^me un fardeau qu'ici j'ai de`pose`. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message