[WorksForMe] Windows guest shows only one cpu

[HAKAK]

Hello,

I'm new here and have searched a lot to solve my problem.

I have a Intel Xeon box (2 processors, 16 cores) with debian buster as host OS.
There are 3 guests:
1 debian buster headless acting as samba server
2 Windows Server 2016 headless
I have assigned 4 cores to each of the VMs.
The debian VM works well and runs 4 cores assigned without problems.
The two Windows VM show only 1 cpu and I can't find out what's wrong. Virtualbox shows the 4 assigned cores in showvminfo as well as in the web interface.
What can I do that the 2 Windows VMs get their 4 cores.
I have attached the showvminfo and log file of one of these machines

Thanks in advance

[socratis]

I have assigned 4 cores to each of the VMs.

1 debian buster headless acting as samba server, 2 Windows Server 2016 headless

00:00:00.323348 CPUM: Physical host cores: 8

Your math is a little flawed: 3 VMs x 4 CPUs = 12 CPUs. You only have 8 cores, not 16. See for yourself the specifications for your Intel Xeon Silver 4110 CPU. VirtualBox cares about physical processors (cores), not logical ones (threads). Remember that simple rule:

• Total CPUs for your guests + 1 ≤ Host CPU cores.
• Total RAM+vRAM+overhead for your guests ≤ Host available RAM + some.

You should be assigning a max of 2 CPUs/VM, so that 3x2=6 for the VMs, plus 2 for your host.

The two Windows VM show only 1 cpu and I can't find out what's wrong

Are you sure you installed an SMP Windows version? One that (as the SMP implies) can work with multiple CPUs?

[HAKAK]

OK, thanks.
I have been fooled by wrong informations I got from my hardware supplier, hwinfo, and virtualbox, 16 cores were available .
So I will change the numbers of CPUs.
1 for samba, 3 for the windows-VMs and one for the host, hoping this will solve the problem.

Tanks again
BTW: My math isn't flawed

[socratis]

BTW: My math isn't flawed

Of course not, it wasn't flawed, only a little ... optimistic based on your expectations of the hardware.

But then you went ahead and said the following:

1 for samba, 3 for the windows-VMs and one for the host, hoping this will solve the problem.

1+3+1=5. You're missing cores!

On the other front, did you check to see whether you have installed a single-CPU version of Windows? Maybe the licensing? You can always install a Win10 (or Linux*) in a test VM and see what happens...

[HAKAK]

1+3+1=5. You're missing cores!

Assume that your reading is a little flawed
1 for samba, 3 for each (2) Windows-VMs, and one for the host.
1 +3 +3 +1 = 8

The Windows OSs are fully licensed Windows 2016 Server

Greetings

HAKAK

[socratis]

I would use 2 for the Samba server, 2 for each VM and 2 for the host. You got nothing to gain by using 3 in a Win VM (compared to 2).

The two Windows VM show only 1 cpu

I never asked you how exactly you came to that conclusion, what are you using to see the CPUs in your guest? Task Manager? Other?

[HAKAK]

I never asked you how exactly you came to that conclusion, what are you using to see the CPUs in your guest? Task Manager? Other?

I see it in the taskmanager.
After having changed the numbers of CPUs in the way I told you nothing has changed.
The taskmanager still shows 1 CPU

[scottgus1]

Here's a Task Manager from a Server 2016 guest I threw together to see what the Task Manager looked like:

Windows 2016 task manager 2 cpus one graph.png (54.04 KiB) Viewed 2925 times

One graph, but two cores, note the underlined part.

If you see different, please zip and post your guest's .vbox file (right-click the guest in the main Virtualbox window, choose Show in {whatever it is called in Debian}). Also take and post a screenshot of the guest's task manager as a PNG, and crop & resize to get under the forum's 128kB limit.

[HAKAK]

screenshot.PNG (30.09 KiB) Viewed 2924 times

shot after changing numbers of CPUs

Attached logfile.

[scottgus1]

That's not the .vbox file.

While the task manager screenshot shows 1 "kerne", The posted log does show 3 cpu's:

00:00:00.091825 NumCPUs <integer> = 0x0000000000000003 (3)
....
00:00:00.651237 CPUM: Physical host cores: 8

Please run "msconfig", go to the Boot tab, click Advanced Options, then post a screenshot of the BOOT Advanced Options window.

Also look at the Device Manager, under Processors. How many show up? Please post that screenshot too.

[mpack]

Does this VM have an Internet connection?

If this was XP then there would be no mystery: it would have meant that this XP image had been installed on a single core machine. If you transferred the image to a new machine then it would continue to report 1 core until you manually replaced the HAL.

My experience with Win7 and later VMs is that you don't need to do that, they automatically switch to a multiprocessor kernel when more cores are added after installation.

What I don't know is if Win7+ is installed with that capability, or whether it has to download a kernel update from the Internet. All my VMs tend to have Internet access, so I wouldn't see this problem - but hence my opening question.

[HAKAK]

As said above the two machines are Windows 2016 Server.
One indeed was transferred from a physical Machine. The other is a fresh install.
Both show the same behaviour.

[scottgus1]

Mpack's point (I think) is that Window OS's 7 & later are supposed to automatically adjust to having more processors if they were originally installed as one processor then more processors were added later if the OS can reach the internet. Windows 2016 is later than 7 so it's supposed to readjust.

Please take a look at the msconfig & device manager requests in my post above.

[HAKAK]

@scottgus1

after msconfig nothing changed

screenshot2.jpg (47.81 KiB) Viewed 2912 times

[socratis]

If I understand that picture right, you're artificially restricting your OS to 1 CPU. Uncheck that "Prozessoranzahl" checkbox.

Download a Linux LiveDVD, for example SystemRescueCD. Boot the Win2016 VM from the LiveDVD, accepting the defaults. Once you're at the terminal, enter the following command which will give you the number of CPUs:

• 
  nproc

What's the output?