From owner-freebsd-current@FreeBSD.ORG  Sun Jul 12 18:47:49 2009
Return-Path: <owner-freebsd-current@FreeBSD.ORG>
Delivered-To: freebsd-current@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 73DE8106566B
	for <freebsd-current@freebsd.org>; Sun, 12 Jul 2009 18:47:49 +0000 (UTC)
	(envelope-from mike@sentex.net)
Received: from lava.sentex.ca (pyroxene.sentex.ca [199.212.134.18])
	by mx1.freebsd.org (Postfix) with ESMTP id 3F2278FC13
	for <freebsd-current@freebsd.org>; Sun, 12 Jul 2009 18:47:48 +0000 (UTC)
	(envelope-from mike@sentex.net)
Received: from mdt-xp.sentex.net (simeon.sentex.ca [192.168.43.27])
	by lava.sentex.ca (8.14.3/8.14.3) with ESMTP id n6CIjB66091206;
	Sun, 12 Jul 2009 14:45:11 -0400 (EDT) (envelope-from mike@sentex.net)
Message-Id: <200907121845.n6CIjB66091206@lava.sentex.ca>
X-Mailer: QUALCOMM Windows Eudora Version 7.1.0.9
Date: Sun, 12 Jul 2009 14:47:54 -0400
To: Kip Macy <kmacy@freebsd.org>
From: Mike Tancsa <mike@sentex.net>
In-Reply-To: <3c1674c90907120009o330da19ds68c45d0dab6ef81f@mail.gmail.co
 m>
References: <d5992baf0907111024g5e3dddfvdd44a8795543e7a6@mail.gmail.com>
	<3c1674c90907120009o330da19ds68c45d0dab6ef81f@mail.gmail.com>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"; format=flowed
Cc: FreeBSD Current <freebsd-current@freebsd.org>
Subject: Re: Flowtables -- any tuning hints?
X-BeenThere: freebsd-current@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Discussions about the use of FreeBSD-current
	<freebsd-current.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>, 
	<mailto:freebsd-current-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-current>
List-Post: <mailto:freebsd-current@freebsd.org>
List-Help: <mailto:freebsd-current-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>,
	<mailto:freebsd-current-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Sun, 12 Jul 2009 18:47:49 -0000

At 03:09 AM 7/12/2009, Kip Macy wrote:

>You want to avoid hash collisions. So, generally speaking you want the
>hash table to be sized 2x larger than the number of unique connection
>destinations.  You want the maximum number of flows to be as large as
>the maximum number of unique destinations x number of cores. When you
>get to the case of hundreds of thousands of unique destinations as in
>the case of a small ISP doing IP forwarding, you're probably better
>off disabling the flowtable.

Speaking of which, are there are specific tuning suggestions for such 
a case ? eg. 250k routes and a few hundred Mb of traffic ?


         ---Mike