From owner-freebsd-virtualization@freebsd.org Wed Dec 21 16:40:30 2016 Return-Path: Delivered-To: freebsd-virtualization@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id BA76FC8A74B for ; Wed, 21 Dec 2016 16:40:30 +0000 (UTC) (envelope-from freebsd@omnilan.de) Received: from mx0.gentlemail.de (mx0.gentlemail.de [IPv6:2a00:e10:2800::a130]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 5B5B41871 for ; Wed, 21 Dec 2016 16:40:30 +0000 (UTC) (envelope-from freebsd@omnilan.de) Received: from mh0.gentlemail.de (mh0.gentlemail.de [IPv6:2a00:e10:2800::a135]) by mx0.gentlemail.de (8.14.5/8.14.5) with ESMTP id uBLGeSmh042177 for ; Wed, 21 Dec 2016 17:40:28 +0100 (CET) (envelope-from freebsd@omnilan.de) Received: from titan.inop.mo1.omnilan.net (titan.inop.mo1.omnilan.net [IPv6:2001:a60:f0bb:1::3:1]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mh0.gentlemail.de (Postfix) with ESMTPSA id 7B8A63F5; Wed, 21 Dec 2016 17:40:28 +0100 (CET) Message-ID: <585AB07C.6010604@omnilan.de> Date: Wed, 21 Dec 2016 17:40:28 +0100 From: Harry Schmalzbauer Organization: OmniLAN User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; de-DE; rv:1.9.2.8) Gecko/20100906 Lightning/1.0b2 Thunderbird/3.1.2 MIME-Version: 1.0 To: freebsd-virtualization@freebsd.org Subject: Re: Jumbo frames truncated at 4084 bytes by virtio-net? (using if_bridge(4) and vtnet(4) with mtu 9000) References: <585AA902.50907@omnilan.de> In-Reply-To: <585AA902.50907@omnilan.de> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.7 (mx0.gentlemail.de [IPv6:2a00:e10:2800::a130]); Wed, 21 Dec 2016 17:40:28 +0100 (CET) X-Milter: Spamilter (Reciever: mx0.gentlemail.de; Sender-ip: ; Sender-helo: mh0.gentlemail.de; ) X-BeenThere: freebsd-virtualization@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: "Discussion of various virtualization techniques FreeBSD supports." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 21 Dec 2016 16:40:30 -0000 Bezüglich Harry Schmalzbauer's Nachricht vom 21.12.2016 17:08 (localtime): … > Guest flow: > 16:57:06.642073 00:a0:98:73:9f:42 > 96:07:e9:78:c6:ac, ethertype IPv4 > (0x0800), length 4085: 172.21.35.1 > 172.21.35.32: ICMP echo request, id > 27401, seq 0, length 4051 > 16:57:06.642233 96:07:e9:78:c6:ac > 00:a0:98:73:9f:42, ethertype IPv4 > (0x0800), length 4084: truncated-ip - 1 bytes missing! 172.21.35.32 > > 172.21.35.1: ICMP echo reply, id 27401, seq 0, length 405 > > Now my problem is that I can't simply keep guest's mtu at 1500, since > the host will send jumbo frames as answer wich never get through virtio-net. > > Does anybody have an idea how to fix/work arround? For the records, replacing virtio-net with e1000 (as bhyve PCI-slot-resident) solves the jumbo frame issue! It seems 82545EM is fully emulated (not 82545GM which doesn't support jumbo frames) :-) Thank you very much for this nice work! mav's commit (r302504) mentions heavy performance penalties (factor 2). Has anyone tried the influence of disabling/keeping offload functions in the guest? Thanks, -Harry