From owner-cvs-all@FreeBSD.ORG  Mon Jun 27 20:12:03 2005
Return-Path: <owner-cvs-all@FreeBSD.ORG>
X-Original-To: cvs-all@FreeBSD.org
Delivered-To: cvs-all@FreeBSD.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id 59C6316A41C;
	Mon, 27 Jun 2005 20:12:03 +0000 (GMT)
	(envelope-from bright@elvis.mu.org)
Received: from elvis.mu.org (elvis.mu.org [192.203.228.196])
	by mx1.FreeBSD.org (Postfix) with ESMTP id 3F05843D1F;
	Mon, 27 Jun 2005 20:12:03 +0000 (GMT)
	(envelope-from bright@elvis.mu.org)
Received: by elvis.mu.org (Postfix, from userid 1192)
	id 2E3445CA35; Mon, 27 Jun 2005 13:12:03 -0700 (PDT)
Date: Mon, 27 Jun 2005 13:12:03 -0700
From: Alfred Perlstein <alfred@freebsd.org>
To: Luigi Rizzo <rizzo@icir.org>
Message-ID: <20050627201203.GF40423@elvis.mu.org>
References: <200506270736.j5R7a3OZ036531@repoman.freebsd.org>
	<20050627152155.GF93072@ip.net.ua>
	<20050627083101.B56456@xorpc.icir.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20050627083101.B56456@xorpc.icir.org>
User-Agent: Mutt/1.4.2.1i
Cc: cvs-src@FreeBSD.org, Gleb Smirnoff <glebius@FreeBSD.org>,
	Ruslan Ermilov <ru@FreeBSD.org>, cvs-all@FreeBSD.org,
	src-committers@FreeBSD.org
Subject: Re: cvs commit: src/sys/netinet/libalias alias_ftp.c alias_irc.c
	alias_local.h alias_proxy.c alias_skinny.c alias_smedia.c
	alias_util.c
X-BeenThere: cvs-all@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: CVS commit messages for the entire tree <cvs-all.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/cvs-all>,
	<mailto:cvs-all-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/cvs-all>
List-Post: <mailto:cvs-all@freebsd.org>
List-Help: <mailto:cvs-all-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/cvs-all>,
	<mailto:cvs-all-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Mon, 27 Jun 2005 20:12:03 -0000

Vendors don't sell performance, they sell features.

(you can quote me on that.)

* Luigi Rizzo <rizzo@icir.org> [050627 08:31] wrote:
> On Mon, Jun 27, 2005 at 06:21:55PM +0300, Ruslan Ermilov wrote:
> ...
> > Why can't we just say that checksum offloading is incompatible
> > with NAT (like with many other things), and do the software
> > checksum calculations in libalias?
> 
> actually the more i see it the more i think checksum offloading
> is a disgrace rather than a performance boost.
> 
> it needs a lot of special cases throughout the protocol stack
> to be supported properly, which constitutes extra overhead
> with low-end hardware which does not support the offloading;
> 
> it does not pay on small packets such as acks where you have
> to touch the whole packet anyways;
> 
> some hardware needs the checksum engine to be reprogrammed when
> changing protocol type (tcp <-> udp) which require extra I/O
> cycles on the bus that are expensive;
> 
> some hardware has broken checksum engines;
> 
> 	cheers
> 	luigi

-- 
- Alfred Perlstein
- email: bright@mu.org cell: 408-480-4684