From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Ira W. Snyder" Subject: Performance questions using bridge and macvlan Date: Thu, 1 Oct 2009 14:21:33 -0700 Message-ID: <20091001212133.GD28963@ovro.caltech.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii To: netdev@vger.kernel.org Return-path: Received: from ovro.ovro.caltech.edu ([192.100.16.2]:39711 "EHLO ovro.ovro.caltech.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752672AbZJAVVa (ORCPT ); Thu, 1 Oct 2009 17:21:30 -0400 Content-Disposition: inline Sender: netdev-owner@vger.kernel.org List-ID: Hello all, I've got an "interesting" network setup (using bridge), and I wonder if macvlan might help me get some more performance. Unfortunately, there isn't much documentation for macvlan, so I'm asking here. I have a computer acting as an ethernet bridge. NIC A is on a network with a 1500 byte mtu. NIC B is a point-to-point ethernet device with a 64K mtu. Adding both devices to a bridge using brctl works as expected. The computer attached to NIC B can send/recv normal ethernet traffic onto the outside network through NIC A. Unfortunately, the bridge code does not fragment packets, and so the 64K mtu is reduced to a 1500 byte mtu. This kills performance by a factor of about 5x on the point-to-point device. All of my tests were using netperf/netserver running on the machine doing the bridging. Without bridge, using full 64K mtu packets, netperf gives ~600mbit/sec. With brigde, using 1500 byte mtu packets, netperf gives ~120mbit/sec. My question is this: is it possible to setup routing or macvlans such that any traffic from the bridge machine itself travels across the point-to-point link (at full 64K mtu), but any other traffic goes through the bridge (using 1500 byte mtu). I'm aware that either running NAT or routing will fragment packets and solve my problem, but this introduces some complexity in my network setup that I would like to avoid. Thanks, Ira