2.13. Poor Desktop Performance With VRDP on Oracle Linux Platforms (Bug ID 14731581)

This issue is only seen on Oracle Linux hosts that are used as both an Oracle VDI host and an Oracle VM VirtualBox host.

When a virtual machine is run on a host that also hosts the user session, the performance of the desktop is poor when the connection protocol is VRDP.

The problem is caused by a mismatch between the maximum transmission unit (MTU) of the loopback network interface and the Sun Ray Windows connector (uttsc) receive buffer.

The solution is to decrease the MTU of the loopback interface so that it is less than the uttsc receive buffer, which is 8192 bytes. You do this as follows:

  1. Use the ifconfig command to check the current MTU of the loopback interface.

    For example:

    # /sbin/ifconfig lo
    lo        Link encap:Local Loopback  
              inet addr:127.0.0.1  Mask:255.0.0.0
              inet6 addr: ::1/128 Scope:Host
              UP LOOPBACK RUNNING  MTU:16346  Metric:1
              RX packets:134095573 errors:0 dropped:0 overruns:0 frame:0
              TX packets:134095573 errors:0 dropped:0 overruns:0 carrier:0
              collisions:0 txqueuelen:0 
              RX bytes:82894163173 (77.2 GiB)  TX bytes:82894163173 (77.2 GiB)
    
  2. If the MTU is 8192 bytes or more, change the MTU of the loopback interface to 8154 bytes.

    The MTU must be less than 8192 bytes. A value of 8154 bytes has been tested and is known to resolve the performance issue.

    Use the ifconfig command to change the MTU, for example:

    # /sbin/ifconfig lo mtu 8154

    To make the change persist after a reboot, edit the /etc/sysconfig/network-scripts/ifcfg-lo file and add the following line:

    MTU=8154

    Use the ifconfig command to verify that the MTU of the loopback interface has been changed.