From owner-freebsd-pf@FreeBSD.ORG Mon Jan 28 20:40:05 2008 Return-Path: Delivered-To: freebsd-pf@hub.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 0F52A16A41B for ; Mon, 28 Jan 2008 20:40:05 +0000 (UTC) (envelope-from gnats@FreeBSD.org) Received: from freefall.freebsd.org (freefall.freebsd.org [IPv6:2001:4f8:fff6::28]) by mx1.freebsd.org (Postfix) with ESMTP id F13D713C442 for ; Mon, 28 Jan 2008 20:40:04 +0000 (UTC) (envelope-from gnats@FreeBSD.org) Received: from freefall.freebsd.org (gnats@localhost [127.0.0.1]) by freefall.freebsd.org (8.14.2/8.14.2) with ESMTP id m0SKe4tN068360 for ; Mon, 28 Jan 2008 20:40:04 GMT (envelope-from gnats@freefall.freebsd.org) Received: (from gnats@localhost) by freefall.freebsd.org (8.14.2/8.14.1/Submit) id m0SKe4EA068359; Mon, 28 Jan 2008 20:40:04 GMT (envelope-from gnats) Date: Mon, 28 Jan 2008 20:40:04 GMT Message-Id: <200801282040.m0SKe4EA068359@freefall.freebsd.org> To: freebsd-pf@FreeBSD.org From: "=?ISO-8859-1?Q?Ermal_Lu=E7i?=" Cc: Subject: Re: kern/120057: [patch] Allow proper settings of ALTQ_HFSC. The check i wrong since even with the values forbidden from this check you get a concave curve. X-BeenThere: freebsd-pf@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: =?ISO-8859-1?Q?Ermal_Lu=E7i?= List-Id: "Technical discussion and general questions about packet filter \(pf\)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 28 Jan 2008 20:40:05 -0000 The following reply was made to PR kern/120057; it has been noted by GNATS. From: "=?ISO-8859-1?Q?Ermal_Lu=E7i?=" To: "Max Laier" Cc: bug-followup@freebsd.org, eri@freebsd.org Subject: Re: kern/120057: [patch] Allow proper settings of ALTQ_HFSC. The check i wrong since even with the values forbidden from this check you get a concave curve. Date: Mon, 28 Jan 2008 21:03:39 +0100 http://www.sigcomm.org/sigcomm97/papers/p011.pdf If you look at the paper on the link i gave here and i copied a snippet from page 11: To demonstrate H-FSC's ability to ensure low delay for real-time connections, we target for a 5 ms delay for the audio session, and a 10 ms delay for the video session. To achieve these objectives, we assign to the audio session the service curve Sa = (umax a = 160 bytes; dmax a = 5 ms; ra = 64 Kbps), and to the video session the service curve Sv = (umax v = 8 KB; dmax v = 10 ms; rv = 2 Mbps). Also, in order to pass the admission control test, we assign to the FTP session the service curve SFTP = (umax FTP = 4 KB; dmax FTP = 16.25 ms; rFTP = 5 Mbps). The service curves of all the other sessions and classes are linear And the paper specifically states that ALTQ_HFSC implementation doesn't allow for convex curve with a m1 parameter of 0. Furthermore, the check is wrong since the second curve starting point is not (0, 0) but the point where the first curve ends, with x = d and y = conversion of m1. So the resultant curve is concave. Sorry the bug follow up was not complete first time, but was tired when reported. P.S. There is another check actually, but that can be part of another PR, which does not allow setting only the realtime parameter and so forbids making altq non work conserving and being used in admission mode. always if you cipole it with a daemon that makes the propper changes in time.