From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1MTFbH-00086n-9k for qemu-devel@nongnu.org; Tue, 21 Jul 2009 09:41:47 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MTFbC-000852-IB for qemu-devel@nongnu.org; Tue, 21 Jul 2009 09:41:46 -0400 Received: from [199.232.76.173] (port=59692 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MTFbC-00084y-DS for qemu-devel@nongnu.org; Tue, 21 Jul 2009 09:41:42 -0400 Received: from fwil.voltaire.com ([193.47.165.2]:31171 helo=exil.voltaire.com) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1MTFbB-0003RW-S3 for qemu-devel@nongnu.org; Tue, 21 Jul 2009 09:41:42 -0400 Message-ID: <4A65C592.4060103@Voltaire.com> Date: Tue, 21 Jul 2009 16:41:38 +0300 From: Or Gerlitz MIME-Version: 1.0 Subject: Re: [Qemu-devel] [PATCH] net: add raw backend - some performance measurements 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> In-Reply-To: <20090721121420.GA19236@gondor.apana.org.au> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Herbert Xu Cc: Mark McLoughlin , "Michael S. Tsirkin" , netdev@vger.kernel.org, Dor Laor , qemu-devel@nongnu.org, Jan Kiszka 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