hello, everyone!

I've gotten a very interesting result about HVM guest network performance.

As you know, network performance in HVM guests is not so good
(=0.83Mbps: when HVM guests are receiving packets).

However, if we send and receive packets simultaneously, receiving
performance significantly improves
(from 69.38 to 74.01Mbps).

Could you see the following test result?
I'm wondering the reason...
;)

---------------------------------
test
* machineA executes netperf to HVM guest dom(1-7).
*4 HVM guest dom(1-4) only receives the netperf packets.
*3 HVM guest dom(5-7) receives the netperf packets with sending ping.

machineA --- netperf benchmark(TCP) --> HVM guest dom1
machineA --- netperf benchmark(TCP) --> HVM guest dom2
machineA --- netperf benchmark(TCP) --> HVM guest dom3
machineA --- netperf benchmark(TCP) --> HVM guest dom4
machineA --- netperf benchmark(TCP) --> HVM guest dom5 -- ping --> machineB
machineA --- netperf benchmark(TCP) --> HVM guest dom6 -- ping --> machineB
machineA --- netperf benchmark(TCP) --> HVM guest dom7 -- ping --> machineB

->result:
  dom1. 0.83 Mbit/sec
  dom2. 2.23 Mbit/sec
  dom3. 2.33 Mbit/sec
  dom4. 5.43 Mbit/sec
  dom5. 69.38 Mbit/sec
  dom6. 34.17 Mbit/sec
  dom7. 74.01 Mbit/sec
--------------------------------

Network:GigabitEthernet
Host OS:Redhat5.1 Xen
Architecture:x86_84

HVM Guest OS:RedHat5.1
Architecture:x86_64

netperf Ver:2.4.2

netperf execute command:
# netperf -H "guest_dom_IP" -l 300

Hope to hear from you soon!

-Christi,
;)