From owner-freebsd-current@FreeBSD.ORG  Thu Apr 19 21:02:53 2012
Return-Path: <owner-freebsd-current@FreeBSD.ORG>
Delivered-To: current@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52])
	by hub.freebsd.org (Postfix) with ESMTP id 7177A106566B;
	Thu, 19 Apr 2012 21:02:53 +0000 (UTC)
	(envelope-from luigi@onelab2.iet.unipi.it)
Received: from onelab2.iet.unipi.it (onelab2.iet.unipi.it [131.114.59.238])
	by mx1.freebsd.org (Postfix) with ESMTP id 298998FC15;
	Thu, 19 Apr 2012 21:02:52 +0000 (UTC)
Received: by onelab2.iet.unipi.it (Postfix, from userid 275)
	id 2D8A473029; Thu, 19 Apr 2012 23:22:24 +0200 (CEST)
Date: Thu, 19 Apr 2012 23:22:24 +0200
From: Luigi Rizzo <rizzo@iet.unipi.it>
To: "K. Macy" <kmacy@freebsd.org>
Message-ID: <20120419212224.GA95459@onelab2.iet.unipi.it>
References: <20120419133018.GA91364@onelab2.iet.unipi.it>
	<4F907011.9080602@freebsd.org>
	<20120419204622.GA94904@onelab2.iet.unipi.it>
	<CAHM0Q_M4wcEiWGkjWxE1OjLeziQN0vM+4_EYS_WComZ6=j5xhA@mail.gmail.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CAHM0Q_M4wcEiWGkjWxE1OjLeziQN0vM+4_EYS_WComZ6=j5xhA@mail.gmail.com>
User-Agent: Mutt/1.4.2.3i
Cc: Andre Oppermann <andre@freebsd.org>, current@freebsd.org, net@freebsd.org
Subject: Re: Some performance measurements on the FreeBSD network stack
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: Thu, 19 Apr 2012 21:02:53 -0000

On Thu, Apr 19, 2012 at 10:34:45PM +0200, K. Macy wrote:
> >> This is indeed a big problem. ?I'm working (rough edges remain) on
> >> changing the routing table locking to an rmlock (read-mostly) which
> >
> 
> This only helps if your flows aren't hitting the same rtentry.
> Otherwise you still convoy on the lock for the rtentry itself to
> increment and decrement the rtentry's reference count.
> 
> > i was wondering, is there a way (and/or any advantage) to use the
> > fastforward code to look up the route for locally sourced packets ?

actually, now that i look at the code, both ip_output() and
the ip_fastforward code use the same in_rtalloc_ign(...)

> >
> 
> If the number of peers is bounded then you can use the flowtable. Max
> PPS is much higher bypassing routing lookup. However, it doesn't scale
> to arbitrary flow numbers.

re. flowtable, could you point me to what i should do instead of
calling in_rtalloc_ign() ?

cheers
luigi