From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jon Fairbairn Subject: Re: Poor network performance with cable modem assigned to guest Date: Sat, 12 Sep 2009 08:51:06 +0100 Message-ID: References: <200908281335.13684.iggy@theiggy.com> <20090829170341.GA26226@psychosis.jim.sh> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE To: kvm@vger.kernel.org Return-path: Received: from lo.gmane.org ([80.91.229.12]:55283 "EHLO lo.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751665AbZILHv1 (ORCPT ); Sat, 12 Sep 2009 03:51:27 -0400 Received: from list by lo.gmane.org with local (Exim 4.50) id 1MmNOL-0003U0-Vb for kvm@vger.kernel.org; Sat, 12 Sep 2009 09:51:29 +0200 Received: from cpc3-cmbg9-0-0-cust696.cmbg.cable.ntl.com ([81.103.22.185]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Sat, 12 Sep 2009 09:51:29 +0200 Received: from jon.fairbairn by cpc3-cmbg9-0-0-cust696.cmbg.cable.ntl.com with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Sat, 12 Sep 2009 09:51:29 +0200 Sender: kvm-owner@vger.kernel.org List-ID: Jim Paris writes: > Jon Fairbairn wrote: >> Brian Jackson writes: >>=20 >> > On Friday 28 August 2009 01:14:42 pm Jon Fairbairn wrote: >> >> The setup was done through virt-manager. The network between the = host >> >> and guest is a virtual bridge. What I've been trying to do is to = assign >> >> a USB cable modem to the guest, >> > >> > >> > This is probably your problem here. KVM only emulates a usb1.1 >> > controller, >>=20 >> that shouldn't be a problem as the cable modem is only a usb 1.1 dev= ice. >>=20 >> > and from all reports, it doesn't really do that very well. >>=20 >> Not very well? We're talking about a factor of *FIFTY* slow down her= e. >> If I'd implemented the driver in a 1980s lazy functional language I >> would have only expected a factor of ten :-P ;-). > I don't have any specific answers, but you might be able to get some > more info by uncomenting the "//#define DEBUG" in kvm's usb-linux.c. > You might also try capturing the USB traffic (e.g. with wireshark) Thanks for your comments; I was waiting for a time when the network wasn't in constant use to try some experiminents, but unfortunately my ISP has replaced the cable modem with a newer version that doesn't have a USB port, so I have to abandon this approach anyway. [Assigning a physical PCI device to a kvm guest doesn't work with=20 AMD Athlon(tm) 64 X2 Dual Core Processor 4400+ does it?] --=20 J=C3=B3n Fairbairn Jon.Fairbairn@cl.cam= =2Eac.uk