Hello all: I''m running Xen with Gentoo. I setup two network device in Xen guest Gentoo. One of them connect to the Dom0 ethernet card via bridge, and the other connect to Dom0 wireless card via another bridge. The interface in DomU connected to the outside ethernet device have throughput close to Dom0. (927Mbps / 917Mbps) However, the wireless interface have very poor bandwidth (2.2Mbps / 90 Kbps). Is there a reason why wireless transmission is extremely inefficient ? sincerely, -Jerry _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> Hello all: > > I''m running Xen with Gentoo. I setup two network device in Xen guestGentoo.> One of them connect to the Dom0 ethernet card via bridge, and theother> connect to Dom0 wireless card via another bridge. The interface inDomU> connected to the outside ethernet device have throughput close toDom0.> (927Mbps / 917Mbps) However, the wireless interface have very poorbandwidth> (2.2Mbps / 90 Kbps). Is there a reason why wireless transmission isextremely> inefficient ? >How does it compare to the throughput when you are not running xen? Wireless is a half duplex medium, and if you are talking to another wireless device ''through'' an access point it gets even worse as your packet has to be received by the AP, then transmitted to the target, then the response goes back the same way, so it''s not nearly as fast as the sticker on the box says. Are you doing all the right things with the wireless interface? You normally need to NAT the MAC addresses for it to work. James _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
I''ll double check the NAT configurations. Right now I can use wireless in DomU. it is just incredibly slow. I perform the following test through Iperf. laptop A. Setup an Iperf server at Dom0 (1) laptop B. Setup an Iperf client at Dom0, connect to laptop A. Throughput is 2.2Mbps (2) laptop B. Setup an Iperf client at DomU, connect to laptop A. Throughput is 90Kbps DomU throughput degrade to 1/20 of the Dom0. Since this only happen on wireless card, I was wondering if my configuration is wrong. sincerely, -Jerry On Mon, Jan 24, 2011 at 5:33 PM, James Harper <james.harper@bendigoit.com.au> wrote:> > Hello all: > > > > I''m running Xen with Gentoo. I setup two network device in Xen guest > Gentoo. > > One of them connect to the Dom0 ethernet card via bridge, and the > other > > connect to Dom0 wireless card via another bridge. The interface in > DomU > > connected to the outside ethernet device have throughput close to > Dom0. > > (927Mbps / 917Mbps) However, the wireless interface have very poor > bandwidth > > (2.2Mbps / 90 Kbps). Is there a reason why wireless transmission is > extremely > > inefficient ? > > > > How does it compare to the throughput when you are not running xen? > > Wireless is a half duplex medium, and if you are talking to another > wireless device ''through'' an access point it gets even worse as your > packet has to be received by the AP, then transmitted to the target, > then the response goes back the same way, so it''s not nearly as fast as > the sticker on the box says. > > Are you doing all the right things with the wireless interface? You > normally need to NAT the MAC addresses for it to work. > > James > >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> > I''ll double check the NAT configurations. > > Right now I can use wireless in DomU. it is just incredibly slow. > > I perform the following test through Iperf. > > laptop A. Setup an Iperf server at Dom0 > > (1) > laptop B. Setup an Iperf client at Dom0, connect to laptop A.Throughput is> 2.2Mbps > (2) > laptop B. Setup an Iperf client at DomU, connect to laptop A.Throughput is> 90Kbps > > DomU throughput degrade to 1/20 of the Dom0. Since this only happen on > wireless card, I was wondering if my configuration is wrong. >One thing to try is to use ethtool to disable all forms of offload in DomU and Dom0 on the bridge, physical, and virtual interfaces. That should at least confirm that offload is not the cause. A simple tcpdump might show you some checksum issues (assuming you use -s0 to grab the whole frame) but it''s often hard to tell as packets can have no checksum while on the bridge. James _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
I disable all offload from DomU and Dom0. To be more specific, I disable all offload on Dom0 bridge, Dom0 virtual interface, Dom0 physical interface, and DomU virtual interface. The wireless bandwidth on Xen guest is still not compariable to Xen host. The bandwidth is tested by setting iperf client on a Xen host, and connect to the server on another laptop''s Xen host or Xen guest. When I disable all the offload, the bandwidth slightly increase on Xen host (2.2Mbps -> 2.5Mbps). However, the Xen guest still have the bandwidth at the scale of 100k bps. Right now I''m trying to understand how long the packet stay at each interface and see where the congestion happens. But I''m curious is it a common case on Xen or I didn''t setup my wireless correctly. sincerely, -Jerry On Mon, Jan 24, 2011 at 7:16 PM, James Harper <james.harper@bendigoit.com.au> wrote:> > > > I''ll double check the NAT configurations. > > > > Right now I can use wireless in DomU. it is just incredibly slow. > > > > I perform the following test through Iperf. > > > > laptop A. Setup an Iperf server at Dom0 > > > > (1) > > laptop B. Setup an Iperf client at Dom0, connect to laptop A. > Throughput is > > 2.2Mbps > > (2) > > laptop B. Setup an Iperf client at DomU, connect to laptop A. > Throughput is > > 90Kbps > > > > DomU throughput degrade to 1/20 of the Dom0. Since this only happen on > > wireless card, I was wondering if my configuration is wrong. > > > > One thing to try is to use ethtool to disable all forms of offload in > DomU and Dom0 on the bridge, physical, and virtual interfaces. That > should at least confirm that offload is not the cause. > > A simple tcpdump might show you some checksum issues (assuming you use > -s0 to grab the whole frame) but it''s often hard to tell as packets can > have no checksum while on the bridge. > > James >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users