KVM Tuning

For better performance, turn off TSO/GSO in KVM by following these steps:

1. Log in to the KVM host.
2. Check to see if each of the data interface offloads are on or off.

     sudo ethtool -k <interface> | grep offload

   where the <interface> is the data interface.

   [root@localhost ~]# sudo ethtool -k eno1 | grep offload
    tcp-segmentation-offload: on
    udp-fragmentation-offload: off
    generic-segmentation-offload: on
    generic-receive-offload: on
    large-receive-offload: off
    rx-vlan-offload: on
    tx-vlan-offload: on
    l2-fwd-offload: off
    hw-tc-offload: off
    esp-hw-offload: on
    esp-tx-csum-hw-offload: on
    rx-udp_tunnel-port-offload: on 

3. If offload is on, turn it off by entering the following command

   [root@localhost ~]# ethtool -K eno1 rx off tx off tso off ufo off gso off gro off lro off
    Cannot change udp-fragmentation-offload
    [root@localhost ~]# sudo ethtool -k eno1 | grep offload tcp-segmentation-offload: off
    udp-fragmentation-offload: off
    generic-segmentation-offload: off
    generic-receive-offload: off
    large-receive-offload: off
    rx-vlan-offload: on
    tx-vlan-offload: on
    l2-fwd-offload: off
    hw-tc-offload: off
    esp-hw-offload: on
    esp-tx-csum-hw-offload: on
    rx-udp_tunnel-port-offload: on
    [root@localhost ~]#