From owner-freebsd-net@FreeBSD.ORG  Thu Jan 30 15:06:29 2014
Return-Path: <owner-freebsd-net@FreeBSD.ORG>
Delivered-To: freebsd-net@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115])
 (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits))
 (No client certificate requested)
 by hub.freebsd.org (Postfix) with ESMTPS id E296FA43
 for <freebsd-net@freebsd.org>; Thu, 30 Jan 2014 15:06:29 +0000 (UTC)
Received: from esa-jnhn.mail.uoguelph.ca (esa-jnhn.mail.uoguelph.ca
 [131.104.91.44]) by mx1.freebsd.org (Postfix) with ESMTP id A7DC01510
 for <freebsd-net@freebsd.org>; Thu, 30 Jan 2014 15:06:29 +0000 (UTC)
X-IronPort-Anti-Spam-Filtered: true
X-IronPort-Anti-Spam-Result: 
X-IronPort-AV: E=Sophos;i="4.95,750,1384318800"; d="scan'208";a="92376724"
Received: from muskoka.cs.uoguelph.ca (HELO zcs3.mail.uoguelph.ca)
 ([131.104.91.222])
 by esa-jnhn.mail.uoguelph.ca with ESMTP; 30 Jan 2014 10:06:28 -0500
Received: from zcs3.mail.uoguelph.ca (localhost.localdomain [127.0.0.1])
 by zcs3.mail.uoguelph.ca (Postfix) with ESMTP id 2A704B40F9
 for <freebsd-net@freebsd.org>; Thu, 30 Jan 2014 10:06:28 -0500 (EST)
Date: Thu, 30 Jan 2014 10:06:28 -0500 (EST)
From: Rick Macklem <rmacklem@uoguelph.ca>
To: FreeBSD Net <freebsd-net@freebsd.org>
Message-ID: <1217356349.106076.1391094388165.JavaMail.root@uoguelph.ca>
Subject: Re: 64K NFS I/O generates a 34mbuf list for TCP which breaks TSO
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit
X-Originating-IP: [172.17.91.203]
X-Mailer: Zimbra 7.2.1_GA_2790 (ZimbraWebClient - FF3.0 (Win)/7.2.1_GA_2790)
X-BeenThere: freebsd-net@freebsd.org
X-Mailman-Version: 2.1.17
Precedence: list
List-Id: Networking and TCP/IP with FreeBSD <freebsd-net.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/options/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: Thu, 30 Jan 2014 15:06:29 -0000

Hi, just adding one more idea on what to do about this
to the list:
- Add a if_hw_tsomaxseg and modify the loop in tcp_output()
  so that it uses both if_hw_tsomax and if_hw_tsomaxseg to
  decide how much to hand to the device driver in each mbuf list.
  (I haven't looked to see how easy it would be to change this loop.)

rick