From owner-freebsd-net  Thu Aug  3 12:17:21 2000
Delivered-To: freebsd-net@freebsd.org
Received: from info.iet.unipi.it (info.iet.unipi.it [131.114.9.184])
	by hub.freebsd.org (Postfix) with ESMTP id D0CDD37B43C
	for <freebsd-net@FreeBSD.ORG>; Thu,  3 Aug 2000 12:17:17 -0700 (PDT)
	(envelope-from luigi@info.iet.unipi.it)
Received: (from luigi@localhost)
	by info.iet.unipi.it (8.9.3/8.9.3) id VAA23823;
	Thu, 3 Aug 2000 21:17:39 +0200 (CEST)
	(envelope-from luigi)
From: Luigi Rizzo <luigi@info.iet.unipi.it>
Message-Id: <200008031917.VAA23823@info.iet.unipi.it>
Subject: Re: Max data queued for UDP
In-Reply-To: <200008031909.PAA24064@khavrinen.lcs.mit.edu> from Garrett Wollman
 at "Aug 3, 2000 03:09:40 pm"
To: Garrett Wollman <wollman@khavrinen.lcs.mit.edu>
Date: Thu, 3 Aug 2000 21:17:39 +0200 (CEST)
Cc: Archie Cobbs <archie@whistle.com>, freebsd-net@FreeBSD.ORG
X-Mailer: ELM [version 2.4ME+ PL61 (25)]
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: owner-freebsd-net@FreeBSD.ORG
Precedence: bulk
X-Loop: FreeBSD.org

> > What is special about multicast that would be particularly problematic?
> 
> Because you are potentially making many (manual) copies of multicast
> packets which were previously copied-by-reference.
> 

the mbuf is still initialized/copied manually, and i think there is
already some m_pullup() anyways in the code path to bring up the
ip header at least. If the packet fits into one mbuf,
copying 20 bytes or 108 makes very little difference compared with
other costs, right ?

	cheers
	luigi


To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-net" in the body of the message