Slow Java under Win11 vm - Special Java Config?

May 25, 2021
Essen, Germany

I need advice regarding my guest VM or maybe even my Proxmox configuration.On my Proxmox, several virtual machines with Windows 11 are running. Under Windows, I have the TurboMed software from the German CGM Group. TM is written in Java and runs so slowly that a proper workflow can't be established.
The program has a database attached, and the database accesses are normally fast or even faster than with the old "bare metal" setup. What's noticeable is that all accesses, which I would associate with "Java internal" or program parts, for example opening a new window, take a very long time (> 10 seconds) the first time. The second time (I suspect once these have been loaded into memory), they work a bit faster (4 - 7 seconds), but compared to before ("click and go") they are still too slow.
Windows 11 itself operates satisfactorily. It doesn't respond immediately, but in a moment, which I would excuse considering the remote access...

Therefore, I suspect that all commands from the Java framework are affected. Are you aware of a similar problem?

Are there perhaps any special adjustments that I can make a) to Proxmox itself or b) in the Java engine on the guest system to speed up Java processing?

Thank you in advance for your ideas.



Of course, I have already followed many tips from this forum, from the TurboMed community, and what I found on Google.
Thus, the following adjustments have been made on the Proxmox side:
  • Disable Balooning
  • No overcommitting
  • Enabe NUMA (yes, it is a two socket mainboard)
  • Installing and use guest agent and VirtIO driver
  • Computertype while generating VM is Windows 11
  • Controller is "VirtIO SCSI single" and drive is ticked with cache=writeback, discard=on, iothread=1, ssd=1
    • Hypervisor runs ZFS, then there is no option for RAW disk?

Hypervisor hardware: 2x Xeon 4210R, 256 GB RAM, 2x Samsung NVME PCIe 3 in ZFS Raid 1, the hardware is distributed across 10 virtual machines (1 Debian Server, 1, Windows Server 2019 and 8 Windows 11 clients).

qm Config - Client VM:

agent: 1
balloon: 0
bios: ovmf
boot: order=scsi0
cores: 2
cpu: host,flags=+hv-evmcs;+aes
efidisk0: local-zfs:vm-30881-disk-0,efitype=4m,pre-enrolled-keys=1,size=1M
machine: pc-q35-8.0
memory: 16384
meta: creation-qemu=8.0.2,ctime=1694237277
name: vWrk-Win11_01
net0: virtio=xx:xx:xx:xx:xx:xx,bridge=vmbr1,firewall=1,tag=3
numa: 1
onboot: 1
ostype: win11
scsi0: local-zfs:vm-30881-disk-1,cache=writeback,discard=on,iothread=1,size=128G,ssd=1
scsihw: virtio-scsi-single
smbios1: uuid=xxx
sockets: 1
startup: order=42
tablet: 0
tpmstate0: local-zfs:vm-30881-disk-2,size=4M,version=v2.0
vmgenid: xxx


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