Hello Xen Community! I''m an everyday user of Xen. I seem to be experiencing a strange issue with the latest Xen release, 4.0. I believe this is also present in earlier versions. I''d love some help pinpointing the cause. My domU network communications with the outside world appear to be slower than expected. iperf from outside host <=> dom0 (normal "iperf -s" on dom0, "iperf -c dom0" on outside host): [ 3] 0.0-10.1 sec 80.6 MBytes 67.0 Mbits/sec and [ 4] 0.0-10.2 sec 80.6 MBytes 66.1 Mbits/sec iperf from outside host <=> domU (ditto): [ 3] 0.0-10.0 sec 59.5 MBytes 49.7 Mbits/sec and [ 4] 0.0-10.1 sec 59.5 MBytes 49.2 Mbits/sec iperf from dom0 <=> domU (server in domU): [ 3] 0.0-10.0 sec 4.25 GBytes 3.65 Gbits/sec and [ 5] 0.0-10.0 sec 4.25 GBytes 3.65 Gbits/sec So, since the B/W between domU and dom0 is very very high and the latency is low, why is it still faster for me to transfer files TO the dom0 and then later from the dom0 to the domU? This is an issue for fileservers and whatnot. In the real world, an rsync from outside -> dom0 gets around 80Mbps sustained, and an rsync from outside -> domU gets 10Mbps. An rsync from outside -> dom0 -> domU via SSH tunneling still gets 10Mbps! I''m using network-bridge. The dom0 is running pv_ops Gentoo Linux x64 2.6.32.11 (jeremy''s git) and Xen 4. The domU is 2.6.31-gentoo-r10, a vanillaish pv_ops. Both servers have a dedicated, reliable 100Mbps uplink. dom0 CPU is not loaded. The dom0 NIC is a BCM5714. For the rsync performance above, the dest filesystem is on phy-backed disks separate from the dom0 disks, although the dom0 is doing dm-crypt processing. Nonetheless, the dom0 CPU usage is not significant and disk bandwidth doesn''t seem to be the bottleneck. netstat -i on dom0: Kernel Interface table Iface MTU Met RX-OK RX-ERR RX-DRP RX-OVR TX-OK TX-ERR TX-DRP TX-OVR Flg br0 1500 0 647940331 0 0 0 294288838 0 0 0 BMRU eth0 1500 0 1621553 0 0 0 7 0 0 0 BMRU eth1 1500 0 423554110 0 22 0 214062434 0 0 0 BMPRU lo 16436 0 74883 0 0 0 74883 0 0 0 LRU tap1. 1500 0 1005921 0 0 0 3661769 0 0 0 BMRU vif1. 1500 0 0 0 0 0 0 0 2419332 0 BMPRU vif16 1500 0 11980 0 0 0 443636 0 705 0 BMPRU vif2. 1500 0 10899823 0 0 0 13239829 0 93 0 BMPRU vif3. 1500 0 4145086 0 0 0 6586798 0 11 0 BMPRU vif4. 1500 0 10 0 0 0 2418717 0 138 0 BMPRU There are no drops or errors in there. Well, OK, there''s one interface that''s ALL TX drops; I don''t know what''s going on with that, but it''s a vif and this problem isn''t limited to one particular domU. Why would I be observing this behavior? Will I have to use my dom0 as a staging point forever? Bryan Jacobs _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users