[Qemu-devel] [Bug 861141] Re: Installing libvirt-bin qemu slows host network

[michael imelfort]

What I mean is that the incomming speed for the machine with libvirt
installed is negatively affected by the installation.

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Title:
  Installing libvirt-bin qemu slows host network

Status in QEMU:
  New

Bug description:
  Installing the packages needed for qemu-kvm slows don network
  connectivity between two non-virtual machines. Uninstalling the
  packages does not restore the previous network speeds.

  Hardware:
  I have two identical machines (DELL poweredge R815), each with Broadcom 
NetXtreme II BCM57711 10-Gigabit PCIe connected via a 10G switch.
  Each machine runs 4 socket 12 core AMD Opteron(tm) Processor 6174 and 128GB 
of ram

  Software:
  Both machines ar running ubuntu server 10.04 lts Kernels are:
  Linux whitlam 2.6.32-28-server #55-Ubuntu SMP Mon Jan 10 23:57:16 UTC 2011 
x86_64 GNU/Linux
  Linux fraser 2.6.32-28-server #55-Ubuntu SMP Mon Jan 10 23:57:16 UTC 2011 
x86_64 GNU/Linux

  I have installed iperf on both machines and I am trying to install kvm
  on fraser.

  The tests here involve running whitlam as the iperf server and fraser as the 
client.
  On whitlam I run:
  address@hidden:~# iperf -sm

  On fraser I run:
  address@hidden:~# iperf -c whitlam -d

  before installation I get:
  address@hidden:~# iperf -sm
  ------------------------------------------------------------
  Server listening on TCP port 5001
  TCP window size: 85.3 KByte (default)
  ------------------------------------------------------------
  [  5] local 10.168.48.14 port 5001 connected with 10.168.48.13 port 37960
  ------------------------------------------------------------
  Client connecting to 10.168.48.13, TCP port 5001
  TCP window size:   110 KByte (default)
  ------------------------------------------------------------
  [  6] local 10.168.48.14 port 49627 connected with 10.168.48.13 port 5001
  Waiting for server threads to complete. Interrupt again to force quit.
  [  5]  0.0-10.0 sec  10.8 GBytes  9.23 Gbits/sec
  [  5] MSS size 1448 bytes (MTU 1500 bytes, ethernet)
  [  6]  0.0-10.0 sec  10.6 GBytes  9.11 Gbits/sec
  [  6] MSS size 1448 bytes (MTU 1500 bytes, ethernet)

  Which is nice.

  Next I run:

  aptitude -y install qemu-kvm libvirt-bin ubuntu-vm-builder bridge-
  utils kvm

  Which results in:
  address@hidden:~# iperf -sm
  ------------------------------------------------------------
  Server listening on TCP port 5001
  TCP window size: 85.3 KByte (default)
  ------------------------------------------------------------
  [  4] local 10.168.48.14 port 5001 connected with 10.168.48.13 port 56405
  ------------------------------------------------------------
  Client connecting to 10.168.48.13, TCP port 5001
  TCP window size: 1.25 MByte (default)
  ------------------------------------------------------------
  [  6] local 10.168.48.14 port 57001 connected with 10.168.48.13 port 5001
  Waiting for server threads to complete. Interrupt again to force quit.
  [ ID] Interval       Transfer     Bandwidth
  [  4]  0.0-10.0 sec  10.5 GBytes  9.00 Gbits/sec
  [  4] MSS size 1448 bytes (MTU 1500 bytes, ethernet)
  [  6]  0.0-10.0 sec  2.51 GBytes  2.15 Gbits/sec
  [  6] MSS size 1448 bytes (MTU 1500 bytes, ethernet)

  Note that the connection from the machine with KVM installed (fraser)
  to the other machine (whitlam) is not affected. Only the connection
  from whitlam to fraser.

  Both machines are fresh installs with nfs-common, and iperf installed.

  I had problems with qemu version 0.12 and virtio_net so I was using
  Daniel Baumans ppa for virtualisation. But this problem occurs
  regardless of whether I do this or not.

  I am happy to give versions of software but I have no idea which part
  could be causing this problem and installing kvm etc installs quite a
  few dependencies.

  Please let me know if you need more information

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