u/eld101

Getting True CPU Utilization on Hyper-V Hosts in Zabbix

I'm trying to get accurate CPU utilization figures for my Hyper-V hosts in Zabbix, but I'm running into a discrepancy between what Zabbix reports and what I'm actually seeing in Windows.

The Problem: Zabbix (and Task Manager) are only reporting CPU usage for the host OS partition itself — not including the load from guest VMs. Resource Monitor, on the other hand, shows the true aggregate utilization including all VM workloads.

As you can see in my screenshot, Task Manager and Zabbix both show ~4% CPU — but Resource Monitor is sitting closer to 50%, which is the real picture when you factor in the VMs running on the host.

What I've tried / what I know:

• Zabbix is pulling the standard Windows CPU performance counter, which only reflects the root partition
• Resource Monitor appears to use a different counter that accounts for hypervisor-level usage

What I'm looking for: Has anyone successfully configured Zabbix to capture true host CPU utilization on Hyper-V — the kind that includes VM guest load? Specifically, I'm wondering if there's a Hyper-V-specific WMI query or a performance counter (like Hyper-V Hypervisor Logical Processor) that would give the right number.

Any tips or working templates would be greatly appreciated!

Anyone else run into this after a Windows update a few months back? My Hyper-V host CPU in Task Manager shows ~2% utilization no matter what my VMs are doing. A few months back it felt accurate — if a VM was under load, you'd see it on the host. Now it's completely disconnected.

To reproduce it, I wrote a Python script to max out every vCPU on a guest VM. htop inside the VM confirms all cores pinned at 100% (see screenshot — 12 threads running, load average 6.15). Meanwhile, the host Task Manager barely moves. The host is an Intel Xeon Gold 6526Y with 32 logical processors and 128GB RAM, so it's not a resource ceiling issue.

My theory is that a Windows update changed how Hyper-V reports guest CPU activity to the host's performance counters, or something shifted in the hypervisor scheduling layer. The VM is clearly doing real work — the host just stopped caring to report it.

Has anyone found a fix or rollback path? I'd rather not start bisecting months of cumulative updates blind.