@olivierlambert we are using Oracle Linux, is OEL8/9/10 supported? As I understand OEL8 and 9 do contain a fix. We can also try with any other OS suggested by you. Thanks!

Hello!
First of all thank you very much for providing the fix!

Following the blog post https://xcp-ng.org/blog/2025/09/01/september-2025-maintenance-update-for-xcp-ng-8-3/:

The change only affects Linux guests. To make it effective, their kernel must support the feature which enables this fix. Linux distributions that have recent enough kernels or apply fixes from the mainline LTS kernels support it. Older ones don't (example: Ubuntu 20.04). Some currently supported LTS distros don't have the required patch yet, notably RHEL 8 and 9 and their derivatives. This might change if we can convince them to apply the patch to their kernel.

Where can we find the list of the supported OS and kernels to run some?

Hello everyone!

It looks like we are also affected with the issue. A week of investigation led us to this thread and our test results are very close to what is described here.

We have VM routers based on OEL8 (tested with all available kernels), xcp-ng 8.2, AMD EPYC 7443P 24-Core Processor, NICs: BCM57416 NetXtreme-E Dual-Media 10G RDMA Ethernet Controller

Network performance has significantly degraded after moving the VMs to the EPYC hosts, tests were performed with iperf:

1. iperf hosts outside of the hypevisor, VM-router on the hypervisor:
   UDP and TCP: ~1.5Gbps
2. both iperf hosts and a router on the hypervisor:
   UDP ~1.5Gbps, TCP ~7Gbps

We have tried SR-IOV and made a test with one 10Gb NIC and got ~9Gbps with TCP and around 4Gbps with UDP.

SR-IOV however seems not usable for us since it looks like we cannot use it over LACP which is required for other VMs redundancy. Alternatively we need to use some additional NICs to use with SR-IOV on our routers or seek for some other connection options within our datacenter.