Chapter 28. Configuring ethtool settings in NetworkManager connection profiles

Procedure

1. For example, to enable the RX offload feature and disable TX offload in the enp1s0 connection profile, enter:

   # nmcli con modify enp1s0 ethtool.feature-rx on ethtool.feature-tx off

   This command explicitly enables RX offload and disables TX offload.

2. To remove the setting of an offload feature that you previously enabled or disabled, set the feature’s parameter to a null value. For example, to remove the configuration for TX offload, enter:

   # nmcli con modify enp1s0 ethtool.feature-tx ""

3. Reactivate the network profile:

   # nmcli connection up enp1s0

Procedure

1. Create a playbook file, for example ~/playbook.yml, with the following content:

   ---
   - name: Configure the network
     hosts: managed-node-01.example.com
     tasks:
       - name: Ethernet connection profile with dynamic IP address settings and offload features
         ansible.builtin.include_role:
           name: rhel-system-roles.network
         vars:
           network_connections:
             - name: enp1s0
               type: ethernet
               autoconnect: yes
               ip:
                 dhcp4: yes
                 auto6: yes
               ethtool:
                 features:
                   gro: no
                   gso: yes
                   tx_sctp_segmentation: no
               state: up

   The settings specified in the example playbook include the following:

   gro: no

   Disables Generic receive offload (GRO).

   gso: yes

   Enables Generic segmentation offload (GSO).

   tx_sctp_segmentation: no

   Disables TX stream control transmission protocol (SCTP) segmentation.

   For details about all variables used in the playbook, see the /usr/share/ansible/roles/rhel-system-roles.network/README.md file on the control node.

2. Validate the playbook syntax:

   $ ansible-playbook --syntax-check ~/playbook.yml

   Note that this command only validates the syntax and does not protect against a wrong but valid configuration.

3. Run the playbook:

   $ ansible-playbook ~/playbook.yml

Procedure

1. For example, to set the maximum number of received packets to delay to 128 in the enp1s0 connection profile, enter:

   # nmcli connection modify enp1s0 ethtool.coalesce-rx-frames 128

2. To remove a coalesce setting, set it to a null value. For example, to remove the ethtool.coalesce-rx-frames setting, enter:

   # nmcli connection modify enp1s0 ethtool.coalesce-rx-frames ""

3. To reactivate the network profile:

   # nmcli connection up enp1s0

Verification

1. Use the ethtool -c command to display the current offload features of a network device:

   # ethtool -c network_device

Procedure

1. Create a playbook file, for example ~/playbook.yml, with the following content:

   ---
   - name: Configure the network
     hosts: managed-node-01.example.com
     tasks:
       - name: Ethernet connection profile with dynamic IP address settings and coalesce settings
         ansible.builtin.include_role:
           name: rhel-system-roles.network
         vars:
           network_connections:
             - name: enp1s0
               type: ethernet
               autoconnect: yes
               ip:
                 dhcp4: yes
                 auto6: yes
               ethtool:
                 coalesce:
                   rx_frames: 128
                   tx_frames: 128
               state: up

   The settings specified in the example playbook include the following:

   rx_frames: <value>

   Sets the number of RX frames.

   gso: <value>

   Sets the number of TX frames.

   For details about all variables used in the playbook, see the /usr/share/ansible/roles/rhel-system-roles.network/README.md file on the control node.

2. Validate the playbook syntax:

   $ ansible-playbook --syntax-check ~/playbook.yml

   Note that this command only validates the syntax and does not protect against a wrong but valid configuration.

3. Run the playbook:

   $ ansible-playbook ~/playbook.yml

Procedure

1. Display the packet drop statistics of the interface:

   # ethtool -S enp1s0
       ...
       rx_queue_0_drops: 97326
       rx_queue_1_drops: 63783
       ...

   Note that the output of the command depends on the network card and the driver.

   High values in discard or drop counters indicate that the available buffer fills up faster than the kernel can process the packets. Increasing the ring buffers can help to avoid such loss.

2. Display the maximum ring buffer sizes:

   # ethtool -g enp1s0
    Ring parameters for enp1s0:
    Pre-set maximums:
    RX:             4096
    RX Mini:        0
    RX Jumbo:       16320
    TX:             4096
    Current hardware settings:
    RX:             255
    RX Mini:        0
    RX Jumbo:       0
    TX:             255

   If the values in the Pre-set maximums section are higher than in the Current hardware settings section, you can change the settings in the next steps.

3. Identify the NetworkManager connection profile that uses the interface:

   # nmcli connection show
   NAME                UUID                                  TYPE      DEVICE
   Example-Connection  a5eb6490-cc20-3668-81f8-0314a27f3f75  ethernet  enp1s0

4. Update the connection profile, and increase the ring buffers:

   • To increase the RX ring buffer, enter:

     # nmcli connection modify Example-Connection ethtool.ring-rx 4096

   • To increase the TX ring buffer, enter:

     # nmcli connection modify Example-Connection ethtool.ring-tx 4096

5. Reload the NetworkManager connection:

   # nmcli connection up Example-Connection

   Important

   Depending on the driver your NIC uses, changing in the ring buffer can shortly interrupt the network connection.

Procedure

1. Create a playbook file, for example ~/playbook.yml, with the following content:

   ---
   - name: Configure the network
     hosts: managed-node-01.example.com
     tasks:
       - name: Ethernet connection profile with dynamic IP address setting and increased ring buffer sizes
         ansible.builtin.include_role:
           name: rhel-system-roles.network
         vars:
           network_connections:
             - name: enp1s0
               type: ethernet
               autoconnect: yes
               ip:
                 dhcp4: yes
                 auto6: yes
               ethtool:
                 ring:
                   rx: 4096
                   tx: 4096
               state: up

   The settings specified in the example playbook include the following:

   rx: <value>

   Sets the maximum number of received ring buffer entries.

   tx: <value>

   Sets the maximum number of transmitted ring buffer entries.

   For details about all variables used in the playbook, see the /usr/share/ansible/roles/rhel-system-roles.network/README.md file on the control node.

2. Validate the playbook syntax:

   $ ansible-playbook --syntax-check ~/playbook.yml

   Note that this command only validates the syntax and does not protect against a wrong but valid configuration.

3. Run the playbook:

   $ ansible-playbook ~/playbook.yml