On 18/03/2023 14:59, Julie Koubová wrote:
Hey everyone,
I'm running Linux (Home Assistant OS) in Bhyve on FreeBSD 13.1. I use
PCI passthrough to allow the VM to access a USB card with a couple of
radio dongles. The host machine is an Intel Core i3 13100 with 64 GB of
RAM. The CPU has 4 physical cores (8 hyper-threaded). The virtual
machine is assigned four cores.
The host load averages are 0.39 0.39 0.40 right now, which seems way too
much. The same workload was previously handled by a Raspberry Pi 4, and
the CPU usage there was under 10% when not doing anything special.
Inside the guest OS, the CPU usage is reported around 5%, which seems
reasonable.
What's wrong? How can I start debugging this issue? I use ZFS on the
host, vm-bhyve to manage the virtual machines, and I don't have a swap
partition.
I had similar problem few years ago. Never solved. Exhibited on bhyve
and VirtualBox too. The problem was "the more vCPU for VM, the slower VM".
Can you try to set just 1 vCPU to your VM? In my case, VM with 1 vCPU
was fast, almost no overhead, 2 v CPUs slightly slower but 4 or more was
slow as hell.
I would also recommend not to overprovision real CPU core count to vCPU
and not use multi/hyper threading cores as real cores. With your CPU,
use only 4 cores to assign to all your VMs (4 VMs with 1 vCPU each, or 2
VMs with 2 vCPU each, 1 VM with 4 vCPU)
Miroslav Lachman
