From owner-freebsd-net@FreeBSD.ORG  Wed Dec 16 00:30:50 2009
Return-Path: <owner-freebsd-net@FreeBSD.ORG>
Delivered-To: freebsd-net@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 68D6B106566B
	for <freebsd-net@freebsd.org>; Wed, 16 Dec 2009 00:30:50 +0000 (UTC)
	(envelope-from john@traktor.dnepro.net)
Received: from traktor.dnepro.net (roof1.dnepro.net [212.3.111.66])
	by mx1.freebsd.org (Postfix) with ESMTP id DC4308FC0A
	for <freebsd-net@freebsd.org>; Wed, 16 Dec 2009 00:30:49 +0000 (UTC)
Received: from traktor.dnepro.net (localhost [127.0.0.1])
	by traktor.dnepro.net (8.14.3/8.14.3) with ESMTP id nBG0UkHJ063408
	for <freebsd-net@freebsd.org>; Wed, 16 Dec 2009 02:30:47 +0200 (EET)
	(envelope-from john@traktor.dnepro.net)
Received: (from john@localhost)
	by traktor.dnepro.net (8.14.3/8.14.3/Submit) id nBG0UkJX063407
	for freebsd-net@freebsd.org; Wed, 16 Dec 2009 02:30:46 +0200 (EET)
	(envelope-from john)
Date: Wed, 16 Dec 2009 02:30:46 +0200
From: Eugene Perevyazko <john@dnepro.net>
To: "freebsd-net@freebsd.org" <freebsd-net@freebsd.org>
Message-ID: <20091216003046.GA57694@traktor.dnepro.net>
Mail-Followup-To: "freebsd-net@freebsd.org" <freebsd-net@freebsd.org>
References: <20091211102928.GA40831@traktor.dnepro.net>
	<9F5E7B59-0CF1-47A7-BE85-41B2C9F0D22B@gmail.com>
	<20091211105336.GB40831@traktor.dnepro.net>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20091211105336.GB40831@traktor.dnepro.net>
User-Agent: Mutt/1.4.2.3i
Subject: Re: How can I find the reason network writes fail with ENOMEM on
	7.x?
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, 16 Dec 2009 00:30:50 -0000

I've found a high number of failures in output of `vmstat -z` in category of "NetGraph 
data items".
Trying to monitor those failures I see that they increase in short moments and 
stay at the level for longer.
It's like 
NetGraph data items:       36,      546,        1,      545, 514855314626, 1247384311
NetGraph data items:       36,      546,        6,      540, 514855480968, 1247384311
NetGraph data items:       36,      546,        5,      541, 514855721631, 1247384311
NetGraph data items:       36,      546,      507,       39, 514857074684, 1247384437
NetGraph data items:       36,      546,       22,      524, 514857862740, 1247384443
with a second between consecutive lines.

It looks like I need to raise net.graph.maxdata from a default of 512. 
What are the safe values for this tunable cause it carries comment of "limit the 
damage of a DoS"? What kind of DoS is it about?

-- 
Eugene Perevyazko