From mboxrd@z Thu Jan 1 00:00:00 1970 From: Or Gerlitz Subject: Re: [Qemu-devel] [PATCH] net: add raw backend - some performance measurements Date: Tue, 21 Jul 2009 16:41:38 +0300 Message-ID: <4A65C592.4060103@Voltaire.com> References: <20090707145739.GB14392@shareable.org> <4A54B0F1.3070201@voltaire.com> <20090715203806.GF3056@shareable.org> <4A647B72.5090404@Voltaire.com> <20090720155308.GA9327@gondor.apana.org.au> <4A656824.7070100@Voltaire.com> <20090721072546.GA16131@gondor.apana.org.au> <20090721102733.GB22155@redhat.com> <4A65A0FC.6090204@Voltaire.com> <20090721120142.GA23439@redhat.com> <20090721121420.GA19236@gondor.apana.org.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: "Michael S. Tsirkin" , Jamie Lokier , Anthony Liguori , qemu-devel@nongnu.org, Jan Kiszka , Mark McLoughlin , Dor Laor , netdev@vger.kernel.org To: Herbert Xu Return-path: Received: from fwil.voltaire.com ([193.47.165.2]:31217 "EHLO exil.voltaire.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754524AbZGUNlr (ORCPT ); Tue, 21 Jul 2009 09:41:47 -0400 In-Reply-To: <20090721121420.GA19236@gondor.apana.org.au> Sender: netdev-owner@vger.kernel.org List-ID: Herbert Xu wrote: > On Tue, Jul 21, 2009 at 03:01:42PM +0300, Michael S. Tsirkin wrote: >> the thing to check then would be that some kind of misconfiguration >> does not cause the bridge to flood your packets to multiple interfaces. > Right, we should make sure that the interfaces are not in promiscous mode Michael, Herbert, First, I don't see how flooding can happen in my setup, I have only two interfaces on the bridge (see below), a tap and a NIC (vlan) and the bridge will never attempt to forward a packet through the port it was received. Second, the bridge always set all interfaces attached to it to be in promiscous mode, see the call to dev_set_promiscuity() from br_add_if() but this doesn't mean it applied flooding, it does mac learning... Or. # brctl show bridge name bridge id STP enabled interfaces br0 8000.0030485f9977 no eth1.4009 tap0 The VM mac is de:ab:be:01:01:09 and the remote node mac is 00:30:48:65:a6:2b, you can see that these two macs were learned by the bridge and hence no flooding is expected. # brctl showmacs br0 port no mac addr is local? ageing timer 1 00:30:48:5f:99:77 yes 0.00 1 00:30:48:65:a6:2b no 12.50 2 06:f5:76:64:a0:d4 yes 0.00 2 de:ab:be:01:01:09 no 0.00