From owner-freebsd-net@FreeBSD.ORG Sun Jun 3 12:33:56 2012 Return-Path: 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 16087106564A for ; Sun, 3 Jun 2012 12:33:56 +0000 (UTC) (envelope-from gallatin@myri.com) Received: from mail-gh0-f182.google.com (mail-gh0-f182.google.com [209.85.160.182]) by mx1.freebsd.org (Postfix) with ESMTP id B851D8FC0C for ; Sun, 3 Jun 2012 12:33:55 +0000 (UTC) Received: by ghbz22 with SMTP id z22so3361758ghb.13 for ; Sun, 03 Jun 2012 05:33:55 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding :x-gm-message-state; bh=ejU0cfAhprEjCC/hLeIbq2an4lww+cbunswwBaJG/Xc=; b=CAKX73xgJPTWlRd1BOtIoPWeVxQdTssrojhEJRxutZED0O41iyEhxikjZcgY2aoS2Y fINj/oYVm7kuV+k1NAFDkmVIyVUyhjVxy3ZTNJJpTWLqEbrgVg44MIbEimqveBEnJsyo mkTGeFQMSZLCq2ZwBztByAgIQ/Wt7s8ZbIP6R34RfmJj5/+pdHZOB9nNfKpKiUy8Y+uH tK/Vs3b8tqPOLOQ4qwkz1dPtDA+BrWoFxOKV3NrOKtbyRRrH5VlvGFaWsWnd6Zg2otAm dmIWBmVaAEFL4bL54OpDqQhNH0NWAdo8bMhkrBqMoYhml+5cHHMw9HsMkI66o9CIT5J2 IXzw== Received: by 10.236.145.168 with SMTP id p28mr4095895yhj.4.1338726835213; Sun, 03 Jun 2012 05:33:55 -0700 (PDT) Received: from [192.168.200.2] (c-24-125-204-77.hsd1.va.comcast.net. [24.125.204.77]) by mx.google.com with ESMTPS id c8sm19580382yhm.18.2012.06.03.05.33.54 (version=SSLv3 cipher=OTHER); Sun, 03 Jun 2012 05:33:54 -0700 (PDT) Message-ID: <4FCB59B1.2050908@myri.com> Date: Sun, 03 Jun 2012 08:33:53 -0400 From: Andrew Gallatin User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:11.0) Gecko/20120329 Thunderbird/11.0.1 MIME-Version: 1.0 To: Kevin Oberman References: <4FBF88CE.20209@cs.duke.edu> <4FC82D6C.4050309@freebsd.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Gm-Message-State: ALoCoQlzxI1K6xyPzh6v89nRIBbeB6sg3iUscn5kIlbgG9W+FGgofraY01dCuvFRnzU+q+EvElVQ Cc: Lawrence Stewart , Andrew Gallatin , freebsd-net@freebsd.org Subject: Re: Major performance hit with ToS setting X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 03 Jun 2012 12:33:56 -0000 On 06/03/12 01:18, Kevin Oberman wrote: > What can I say but that you are right. When I looked at the interface > stats I found that the link overflow drops were through the roof! This > confuses me a bit since the traffic is outbound and I woudl assume Indeed, link overflow is incoming traffic that was dropped due to lack of rx resources. If you have flow control disabled, it is drops simply due to lack of space in the rx fifo. If you have flow control enabled, link overflow can include drops due to lack of host rx buffers as well. For primarily WAN traffic, we suggest that flow control be disabled (it is enabled by default). With f/c disabled, drops due to lack of rx buffers are counted as dropped_no_[big|small]_buffer At any rate, it is surprising to see link overflow increase on an outgoing unidirectional test. Is there other incoming traffic that you might not have been aware of? The only really unlikely thing I can think of is if something is buffering tens of thousands of acks and dumping them all at once. Drew