From owner-freebsd-net@FreeBSD.ORG Wed Apr 15 18:39:09 2009 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 9ACF91065675 for ; Wed, 15 Apr 2009 18:39:09 +0000 (UTC) (envelope-from mat.macy@gmail.com) Received: from an-out-0708.google.com (an-out-0708.google.com [209.85.132.246]) by mx1.freebsd.org (Postfix) with ESMTP id 516DE8FC0C for ; Wed, 15 Apr 2009 18:39:08 +0000 (UTC) (envelope-from mat.macy@gmail.com) Received: by an-out-0708.google.com with SMTP id d11so26864and.13 for ; Wed, 15 Apr 2009 11:39:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:sender:received:in-reply-to :references:date:x-google-sender-auth:message-id:subject:from:to:cc :content-type:content-transfer-encoding; bh=kkd7PzHvNQ1JIcW2XxGGFuIlib1LET1BKkc5j8JYxuM=; b=D4vuRsZtORIVNIwEsZL777XsJjRToIrkP8jKXmcOs/TaCFl7rnzdGoexaQ+QIr0Dj1 9LTcNBzbw3j9lYlreBnEagPs2NPa5UvOcZjCS3mVSE/EJTYLDGFMFF8wVsuwpXyM1Zw9 S9391V/mAD35pPXjCfPbQqAi1NhJWU5Z/roYs= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type :content-transfer-encoding; b=dQcdre5sWw/62qakA67Hi+87vHE6qZ+Itd6p7aBBbnG0eIQ4J/Rtk4gcb6XKI8DmZN /552eNV3U5j6zZCNOG+9/550DnUzkKKfMkGRqG6y1J1zolhf4BnULzxAXKhScl+8Fa33 JotpgJ6FcvxwWoU0S59w/Tdkz4fGgPC5F3L0s= MIME-Version: 1.0 Sender: mat.macy@gmail.com Received: by 10.100.151.8 with SMTP id y8mr832880and.106.1239818820142; Wed, 15 Apr 2009 11:07:00 -0700 (PDT) In-Reply-To: <20090415084031.6d149fef@renaud-dev1> References: <20090415084031.6d149fef@renaud-dev1> Date: Wed, 15 Apr 2009 11:06:59 -0700 X-Google-Sender-Auth: cd3e7e9a9e708900 Message-ID: <3c1674c90904151106j543d4772s25786f81d7ff55a1@mail.gmail.com> From: Kip Macy To: Renaud Lienhart Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Cc: freebsd-net@freebsd.org Subject: Re: tcp_output() might generate invalid TSO frames 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: Wed, 15 Apr 2009 18:39:10 -0000 Interesting. That might explain a problem that Mike Silbersack is seeing with the latest em driver on vmware. I don't know of any NICs that actually choke on such frames. Nonetheless, it is silly behavior. I'll try to see if we can get this fixed before 7.2. Thanks, Kip On Wed, Apr 15, 2009 at 8:40 AM, Renaud Lienhart wrote: > Hi, > > We're having trouble virtualizing FreeBSD 7+ on ESX because of an issue > with the stack's TSO implementation: it sometimes generates TSO packets > whose payload size is actually smaller than the MSS. > > The faulty logic is described, along with a patch, in PR #132832. It > has been opened for a while now, without any apparent activity, which > is why I'm reaching the mailing list directly. > > ESX currently drops these packets as many physical nics are known to > choke on such frames, which effectively limits FreeBSD guests' > performance. > I don't know about other virtualization stacks' behavior. > > http://www.freebsd.org/cgi/query-pr.cgi?pr=3Dkern/132832 > > Thanks for your time, > > =A0 =A0 =A0 =A0Renaud > _______________________________________________ > freebsd-net@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org" > --=20 All that is necessary for the triumph of evil is that good men do nothing. Edmund Burke