[German]An administrator recently pointed out a very unpleasant finding to me. The Hyper-V virtualization solution promoted by Microsoft can hardly be used in certain scenarios (on AMD and Intel CPUs) to run multiple virtual machines under Windows 11 24H2 or Windows Server 2025. The reason for this is that the operating system does not provide any performance data and the scheduler cannot distribute the resources to the VMs properly.
Advertising
User report about a Hyper-V problem
Blog reader Stephan is an administrator in an organization I know. There, machines with Windows 11 24H2 and Windows Server 2025 are used or at least tested.
In this context, the reader noticed a major problem with Hyper-V on systems with AMD CPUs – it affects at least CPUs from the Zen series, although the Zen version does not seem to be relevant. Under Windows 11 24H2 and Windows Server 2025, "regulation is deactivated under Hyper-V", he wrote, so that the CPU utilization for a VM is always set to zero.
As a result, the scheduler no longer works and the VMs work against each other. It is no longer possible to set a weighting for resource allocation for the VMs (see also the following explanations). According to his statement, this makes it quite difficult to operate several VMs on one host.
The blog reader has been able to observe the behavior outlined in this article on systems with Ryzen 5000 and 9000 CPUs (Asus AM4 x570 ACE and an Asus AM5). I myself have not activated Hyper-V on my Windows 10 clients for some time and could not test anything due to a lack of AMD hardware. When I asked blog reader Stephan for more information, he got back to me (thanks for that) and explained the follow-up problem in more detail.
Why this is relevant?
With Hyper-V, you can specify how heavily a VM is weighted in order to balance the resources between the VMs in this way. The higher the weighting, the more resources the VM receives (a VM with 2200 receives more CPU and IO time than a VM with a weighting of 1100). The scheduler then ensures that everything runs as smoothly as possible.
Advertising
The image above shows a screenshot with the Hyper-V settings (foreground) and the CPU utilization with the value 0% (background). This was not the case before, the reader wrote (probably referring to Windows 11 23H2, Windows Server 2022 etc.).
The consequence of the missing performance indicator values is that the VMs run "laggy", writes the reader. The background to this is that the VMs are constantly competing for resources and the "conductor is asleep" (the scheduler for resource allocation no longer works). For Stefan, it feels like the VM "that starts first gets resources until it is finished".
The result is drastic, as one VM is running, but another VM (or several) is more or less "hanging/hanging", as the scheduler does not distribute the virtual machines properly across the cores and can no longer regulate "which VM receives CPU resources and is allowed to work for how long". Stefan has noticed that the same picture emerges for the IO load on the disks.
At the same time, the display is not correct, writes the blog reader. He could fully utilize a VM with all cores available on the host's hardware with the Cinebench test program. But 0% CPU utilization would be displayed in the manager. Also in the Windows Task Manager only the IO value for DISK0 is displayed, all other values are set to 0% (independent of Hyper-V).
In his reply, the reader confirms that he has also encountered the problem on Windows 11 24H2. However, this client platform only affects users who want to do some desktop virtualization for Hyper-V and may be able to live with the bug. But as explained above, the problem also occurs under Windows Server 2025. So of course virtualization is not possible in an environment with Windows Server 2025. The reader actually wanted to order a new server with Server 2025, but it looks like that would not be a good idea.
A problem description on reddit.com
At this point, the question arises as to whether the above explanations are an isolated case. Stephan then pointed me to the reddit.com thread Hyper-V CPU Usage Always 0% on Windows Server 2025, where the problem is described by the thread starter in a more general form for Windows Server 2025. The person concerned states that the system is a new installation of Windows Server 2025, where there is a problem with Hyper-V. The cause should therefore not be a "corrupted configuration".
Resource metering (for Hyper-V) is activated on the system and the person concerned claims to have checked all relevant settings. However, the CPU utilization for the virtual machines is consistently displayed as 0% in both the Hyper-V Manager and the Performance Monitor.
The thread starter lists everything it has already done (it has even restored the performance counters with lodctr /r, the VM integration services are available, etc.). Nothing helps, after activating the resource measurement via PowerShell (Enable-VMResourceMetering and Measure-VM) he gets no values for the performance monitor. Checking the Hyper-V logs for errors or warnings was unsuccessful.
In the redditc.om thread in question, several participants confirm that they are also facing the problem that no resource values are available under Hyper-V. There is also confirmation that the error also occurs under Windows 11 24H2 in addition to Windows Server 2025. As early as December 2024, someone reported that they were experiencing the error on AMD CPUs. But I got also feedback in my German blog, that Intel CPUs are affected as well.
So far, the updates rolled out by Microsoft for December 2024 and January 2025 have not changed the reported problem. Hyper-V cannot really be used with multiple virtual machines. Can anyone from the readership also confirm this behavior? Are there any known solutions or are there already tickets with Microsoft support?
Advertising
