@olivierlambert Thank you!

Do you actually "feel" the difference in terms of VM performance for your services?

OF COURSE! Was very slow.
You cannot imagine the difference...

This is an AMD Ryzen 9 7950X3D host.
Moreover, since the problem started we migrated several VMs to other hosts.
If you see the screenshots above, in xentop output, besides Dom0, all other VMs where like hardly using 2-3 CPUs in total.
And everything was dead slow (steal time always high).

My feeling here is that this was somehow related to networking (tap*), but really don't know what and why.
Glad this was resolved after the reboot.

Topic restored. @gtuminauskas Please don't remove threads that have been responded to by other forum members.

@Affonso Looks like it might have been Bug 15684 in 24.03 that was resolved for 24.11 (release notes).

@dsmteam Still trying to browse the web and various xo forum but it looks like those parameters are in the .c and other precompile file so the build in xcp-ng are probably using those default parameters.

@Ascar In XO cloud means pool, "hamburger" means host. If VM is running, it belongs to host where it runs, and receives host icon, no matter where it is kept in stopped state. If VM is stopped, it belongs to pool if kept on pool shared storage (cloud icon), or to host, if on host's local storage (hamburger).

@BenjiReis The xapi is written in OCaml? That is pretty cool. I would love to learn OCaml one day.

Anyways, doesn't seem intuitive to design it this way:
334b8d7a-6f7e-4796-97c2-3c1fe4144fb6-Screenshot from 2024-10-22 08-02-03.png

Going to file an issue in that repo to see what happens. I suppose they would have to fix the OCaml code you linked as well.

I've tried an experiment and modified slightly qemu-wrapper script to not add cirrus-vga device to the VM. THe VM starts, but I still have no signal on my HDMI output. Seems like more work needs to be done in order to use my iGPU for display on HDMI output...
Browsing through similar topics on the forum it seems like it's not a supported use case? Are there any plans to support this use case?

@Tackyone
You solution fixed it for me. Lost a few days of logs as well and i am on the latest commit of the XO community edition.

Theres some bug with syslog clear but your fix works great.

Hi,

It's a complex situation, nested doesn't work well in many situation. It's in our backlog.

@enes-selcuk Did you find a setting that works best w/ Dell servers?

I have a Dell R640's which I'll be using for LAMP/LEMP vm servers and was wondering what are the best settings to use in Dell Bios and if there are any changes I need to make on the xcp-ng host?

Dual Intel(R) Xeon(R) Gold 5218 CPU @ 2.30GHz
Level 2 Cache 16x1 MB
Level 3 Cache 22 MB
Number of Cores 16

Dell Bios Setting:
System Profile: Performance Per Watt (OS)
CPU Power Management: OS DBPM
Memory Frequency: Maximum Performance
Turbo Boost: Enabled
C1E: Enabled
C States: Enabled
Write Data CRC: Disabled
Memory Patrol Scrub: Standard
Memory Refresh Rate: 1x
Uncore Frequency : Dynamic
Energy Efficient Policy: Balanced Performance
Number of Turbo Boost Enabled Cores for Processor 1: All
Number of Turbo Boost Enabled Cores for Processor 2: All
Monitor/Mwait: Enabled
Workload Profile: Not Available
CPU Interconnect Bus Link Power Management: Enabled
PCI ASPM L1 Link Power Management: Enabled

Thank you!

SW

@stormi oh I see, I'll check the windows 10 vm's then, thank you

@andrewperry yeah try set it 16/16Gb instead, it will probably do some magic 🙂

I'm taking another look and it looks like the tools may be under another name... xen-tools

I may be going blind at this point if I've missed it this many times.

Ya,
for the working machine I just had to run

opt/xensource/libexec/xen-cmdline --set-dom0 "xen-pciback.hide=(0000:00:02.0)"

and on next reboot I could add the GPU as pass through in XOA. for the other machine this didn’t work but using xcp-center did make it show up as a pass through option

@stormi said in Nested Virtualization of Windows Hyper-V on XCP-ng:

Actually, Xen never officially supported Nested Virtualization. It was experimental, and broke when other needed changes were made to Xen. Now there's work to be done to make it fully supported, and this won't happen before the final release of XCP-ng 8.3. This will be documented in the release notes.

This is also an issue for us internally as we create a lot of virtual pools for our tests.

I read through a lot of the earlier posts and finally started scrolling to find this, which is the answer I was looking for. Why do I care? There is a Microsoft evaluation learning lab for things like Intune that runs in Hyper-V, basically a bunch of VHD (x) that get spawned as needed. Applications I need to teach myself. Running XCP-NG 8.3 current updates for this lab.

If it doesn't happen, then I'll just need to throw an eval version of Windows Server on something else like an HP T740 to run these labs, not the biggest issue for me.

Link for the labs if anyone is curious (free with an email registration like all the evals):

https://www.microsoft.com/en-us/evalcenter/evaluate-mem-evaluation-lab-kit

I'd think direct Docker support would be a higher priority than nested virtualization with a focus on Hyper-V. But that's just me.

Hello! My apologies -- I hadn't gotten around to trying this solution out until now.

I just did and it appears to have fixed the issue! VMs are booting correctly and I can interact with them normally through the console.

Can also confirm it works on both the 1.29 Dell FW from my original post, as well as the latest 1.32 FW available as of this post.

Much thanks @andyhhp and @stormi for both your time and effort in packaging this -- I greatly appreciate it! 🙂