Enable NIC Multi-Queue for Virtual Machines (VMs)

NIC Multi-Queue is off by default and must be explicitly turned on using the DCD or IONOS Cloud API for each VM.

Note: The following table provides information on which Compute Services the feature is available.

Compute Services	Available?
Dedicated Core Servers	✅
vCPU Servers	✅
Cubes	❌

1

Verify the number of queues before enabling NIC Multi-Queue

Use the ethtool -l command to query the maximum and current settings for the receive (RX), transmit (TX), and combined queue channels on a specified network device. The following example uses ens6 as the NIC.

To verify the number of queues configured on each NIC, use the following command:

root@ubuntu:~# ethtool -l ens6
Channel parameters for ens6:
Pre-set maximums:
RX:  n/a
TX:  n/a
Other:  n/a
Combined: 1
Current hardware settings:
RX:  n/a
TX:  n/a
Other:  n/a
Combined: 1

The output shows that the NIC ens6 is configured for:

• Maximum combined queues: 1

• Current hardware settings (combined): 1

The output indicates that, at the hardware level, ens6 is not currently configured to utilize multiple queues. It is limited to a single combined queue for both sending TX and receiving RX traffic. This baseline check confirms queue capacity before attempting an NIC Multi-Queue setup.

2

Verify the number of queues after enabling NIC Multi-Queue

To verify the number of queues configured on each NIC, use the following command:

Note: The example below is for a VM configured with four threads.

root@ubuntu:~# ethtool -l ens6
Channel parameters for ens6:
Pre-set maximums:
RX:		n/a
TX:		n/a
Other:		n/a
Combined:	4
Current hardware settings:
RX:		n/a
TX:		n/a
Other:		n/a
Combined:	4

root@ubuntu:~# ls /sys/class/net/ens6/queues/
rx-0  rx-1  rx-2  rx-3  tx-0  tx-1  tx-2  tx-3

The output shows that the NIC ens6 is configured for:

• Maximum combined queues for RX-only or TX-only queues: 4

• Current hardware settings (combined): 4

At the hardware level, NIC Multi-Queue is enabled and configured on the ens6 interface for utilizing maximum parallelism, containing a maximum of four combined queues. The output shows that NIC Multi-Queue can now distribute traffic across four CPU cores simultaneously for both sending TX and receiving RX traffic.

3

Improve your network performance

We recommend unsetting CPU affinity and TCP tuning depending on your use case to further improve the network performance.

Unset CPU affinity

Use the following command to disable Transmit Packet Steering (XPS) by setting all CPU affinity masks to `00000000`. It loops through all transmit queues `tx-*` for the `ens6` network interface and writes `00000000` to the `xps_cpus` file for each queue. You can use the command to handle queue distribution automatically rather than manually, and to prevent pinning specific transmit queues to specific CPUs.

for f in /sys/class/net/ens6/queues/tx-*/xps_cpus; do echo 00000000 | tee $f; done

TCP Tuning