Bug ID 2183761: Improper VM Tenant Thread CPU pinning may cause overlap with dma-agent threads

Last Modified: Aug 27, 2026

Affected Product(s):
F5OS None(all modules)

Fixed In:
F5OS-C 1.8.2-HR1

Opened: Dec 10, 2025

Severity: 2-Critical

Symptoms

Symptoms would be loss of performance.

Impact

This can lower system performance, if the kvm threads try to run on the same processor as other datapath-critical threads (like dm-worker threads from the dma-agent).

Conditions

During tenant deployment, two mechanisms attempt to pin the tenant's KVM CPUs. 1.Custom code added to the KubeVirt virt-launcher pod. 2. The libvirt daemon responsible for launching the QEMU process. While our code performs CPU pinning, the libvirt daemon occasionally unpins the CPUs. In some cases, the Libvirt unpinning takes precedence, resulting in tenant threads being left unpinned. This is more likely to happen on large systems with large tenants, or many tenants.

Workaround

There is no reliable workaround, but one could try toggling the tenant from deployed -> configured -> deployed and give another chance to the two entities that are pinning/un-pinning the kvm threads.

Fix Information

None

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips