Bug ID 634132: VE: virtio high performance driver (Linux/KVM)

Last Modified: Aug 19, 2026

Affected Product(s):
BIG-IP MA-VE(all modules)

Known Affected Versions:
13.0.0, 13.0.0 hf1, 13.0.0 hf2, 13.0.0 hf3, 13.0.1

Opened: Dec 16, 2016

Severity: 2-Critical

Symptoms

By default, the UNIC driver is used for virtio devices on Linux/KVM hypervisors, and at higher network speeds, the soft IRQ interrupt load competes with tmm. This can be observed under load with the "top" linux command showing ksoftirqd soft IRQ load.

Impact

Potential performance issues (CPU utilization, throughput, connections/second).

Conditions

Version 13.0.0 default behavior on Linux/KVM hypervisor with virtio nic(s) presented to the guest. Note: To determine what driver is in use for each nic, use following command: tmctl -d blade tmm/device_probed.

Workaround

None.

Fix Information

None

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips