From owner-freebsd-net@FreeBSD.ORG  Wed Jan 24 13:49:34 2007
Return-Path: <owner-freebsd-net@FreeBSD.ORG>
X-Original-To: freebsd-net@freebsd.org
Delivered-To: freebsd-net@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52])
	by hub.freebsd.org (Postfix) with ESMTP id 5902D16A402
	for <freebsd-net@freebsd.org>; Wed, 24 Jan 2007 13:49:34 +0000 (UTC)
	(envelope-from rizzo@icir.org)
Received: from xorpc.icir.org (xorpc.icir.org [192.150.187.68])
	by mx1.freebsd.org (Postfix) with ESMTP id 4657013C4D1
	for <freebsd-net@freebsd.org>; Wed, 24 Jan 2007 13:49:34 +0000 (UTC)
	(envelope-from rizzo@icir.org)
Received: from xorpc.icir.org (localhost [127.0.0.1])
	by xorpc.icir.org (8.12.11/8.13.6) with ESMTP id l0ODnVAe056621;
	Wed, 24 Jan 2007 05:49:31 -0800 (PST)
	(envelope-from rizzo@xorpc.icir.org)
Received: (from rizzo@localhost)
	by xorpc.icir.org (8.12.11/8.12.3/Submit) id l0ODnV2Q056620;
	Wed, 24 Jan 2007 05:49:31 -0800 (PST) (envelope-from rizzo)
Date: Wed, 24 Jan 2007 05:49:31 -0800
From: Luigi Rizzo <rizzo@icir.org>
To: Randall Stewart <rrs@cisco.com>
Message-ID: <20070124054931.B56550@xorpc.icir.org>
References: <45B679F3.3080407@cisco.com> <20070124051050.A56064@xorpc.icir.org>
	<45B7631A.3070001@cisco.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
User-Agent: Mutt/1.2.5.1i
In-Reply-To: <45B7631A.3070001@cisco.com>;
	from rrs@cisco.com on Wed, Jan 24, 2007 at 08:46:02AM -0500
Cc: freebsd-net <freebsd-net@freebsd.org>
Subject: Re: mbuf patch with sysctl suggestions too
X-BeenThere: freebsd-net@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Networking and TCP/IP with FreeBSD <freebsd-net.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-net>,
	<mailto:freebsd-net-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-net>
List-Post: <mailto:freebsd-net@freebsd.org>
List-Help: <mailto:freebsd-net-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-net>,
	<mailto:freebsd-net-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Wed, 24 Jan 2007 13:49:34 -0000

On Wed, Jan 24, 2007 at 08:46:02AM -0500, Randall Stewart wrote:
> Luigi Rizzo wrote:
> > On Tue, Jan 23, 2007 at 04:11:15PM -0500, Randall Stewart wrote:
> >> Hi all:
> >>
> >> Here is iteration 2 of the mbuf patch with limits I
> >> proposed.
> >>
> >> Also note the changes for sysctl stuff that Lugi suggested.
> >> Please let me know what you think :-)
> > 
> > ...
> >> +	newnmbjclusters = nmbjumbop;
> >> +	error = sysctl_int_checked(oidp, &newnmbjclusters, nmbjumbop, 
> >> +           SYSCTL_NO_LIMIT, req);
> > 
> > A few things here:
> > - i don't see much of a point in defining SYSCTL_NO_LIMIT;
> >   UINT32_MAX would do perfectly there, and i think it is easier
> >   to understand than SYSCTL_NO_LIMIT (which looks like a flag).
> > 
> 
> ok
> > - here and in other places you do not allow decresaing the value
> >   (by putting min = nmbjumbop etc.), and i am not sure why.
> >   I understand a reasonable lower bound, but i guess the worst
> >   that can happen, when you reduce the limit to something above
> >   the current allocation, is that nothing is allocated until
> >   you go again below the limit, right ?
> 
> Well.. no I believe someone (was in Lin) mentioned that
> you can get a live-lock if you allow a reduction.. and
> thus the mbuf clusters were NOT allowed to be reduced..

maybe... but then this is definitely worth putting a note
explaining why.

	cheers
	luigi