Virtual Box gets extremely slow when running 6 VMs simultaneously

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SebHellYea
Posts: 5
Joined: 2. May 2021, 20:49

Virtual Box gets extremely slow when running 6 VMs simultaneously

Post by SebHellYea »

hello,

my sys specs are:

CPU: Intel Core i9 10900X 10x 3.70GHz
Mobo: ASRock X299 Steel Legend
RAM: 256GB DDR4
HDD: 4TB SATA
GPU: 2GB MSI GeForce GT 1030
Host OS: Win 10 Pro

When booting the first of my VMs it runs smoothly but when running 6 VMs simultaneously they all get super slow. Especially booting: when booting the 2nd VM it will add around 2 mins of boot time compared to booting the first VM and when booting the 3rd VM it will add another 2 mins and so on so when booting the 6th VM the booting alone takes around 10 mins! There must be something wrong with my system I reckon since my hardware should be more than enough to run 6 VMs simultaneously without any performance issues. I am not running the VMs inside a VM but I am running all 6 VMs on the host. I did install the toolbox on all 6 VMs. In fact I cloned the first VM 5 times so I got 6 identical VMs in total.

I attached the logs of all 6 VMs here. BTW I could not supply the log of 3 of my 6 VMs since a logfile in there was around 2GB of file size!? How can a log get that big?

Please let me know what is the reason for this miserable VM performance on my system.

Thanks in advance

Seb
Attachments
VM5.zip
VM5Log
(153.1 KiB) Downloaded 9 times
VM4.zip
VM4Log
(179.42 KiB) Downloaded 9 times
VM3.zip
VM3Log
(173.48 KiB) Downloaded 9 times
scottgus1
Site Moderator
Posts: 20965
Joined: 30. Dec 2009, 20:14
Primary OS: MS Windows 10
VBox Version: PUEL
Guest OSses: Windows, Linux

Re: Virtual Box gets extremely slow when running 6 VMs simultaneously

Post by scottgus1 »

That's a very well-provisioned host you have! 10 hyperthreaded cores, 256GB RAM... Nice.
SebHellYea wrote:running 6 VMs simultaneously
SebHellYea wrote:what is the reason for this miserable VM performance
The three logged VMs are all on the host's E drive. If E is this:
SebHellYea wrote:HDD: 4TB SATA
and this is a spinning platter drive, then I think we might have found the problem.

More than 2 modern OS's doing heavy disk access, such as booting, will swamp out a platter drive. You have 6 Windows 10's. SSD would probably handle the load, but spinning rust will thumb its nose and say "Back off, dude, don't rush me!!"

If this is an SSD, there could be a problem in the total number of VM processors being used. Each is a clone, and VMs 3, 4, 5 have 5 processors each. Assuming identical specs on each of the 6 VMs, that's 30 processors' worth of threads on a 10-core hyperthreaded host processor (hyperthreads don't help well with Virtualbox). More processors slow down a VM, due to extra scheduling oversight required on the host. Since the VMs are Windows 10, stick to 2 processors each until you install parallel-processing programs in the VMs that can fill up the extra processors. 30 processors might be too much anyway.

VMs 3 and 4 seem to have run without trouble, barring the slowness. VM 5 had this in the log several times:
00:05:41.837593 int __cdecl pgmR0BthAMD64AMD64Trap0eHandler(struct GVMCPU *,unsigned __int64,struct CPUMCTXCORE *,unsigned __int64,bool *): returns rc=0 pvFault=fffff8052baf8724 uErr=11 cs:rip=0010:fffff8052baf8724
I don't recognize it, but the "CPUMCTXCORE" mentioning "CPU" and "CORE" might indicate problems with overloading the CPU.
SebHellYea wrote:a logfile in there was around 2GB of file size!? How can a log get that big?
This is odd. But without knowing what was in the log, we couldn't guess what caused it. If you zip it, how big would it be? Maybe lots of repetitive messages? A les than 128kB zip that expands to over 2GB would be a low-yield zip bomb, but it might indicate lots of repetition.
fth0
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Joined: 14. Feb 2019, 03:06
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Re: Virtual Box gets extremely slow when running 6 VMs simultaneously

Post by fth0 »

Searching for other VBox.log files containing pgmR0BthAMD64AMD64Trap0eHandler messages, I found out that those messages can be generated every few microseconds and naturally can lead to large log files, so I don't think that we'll need the other log files at the moment. Can you please check if the uErr value (part of the message) is the same in the other log files?
fth0
Volunteer
Posts: 5668
Joined: 14. Feb 2019, 03:06
Primary OS: Mac OS X other
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Location: Germany

Re: Virtual Box gets extremely slow when running 6 VMs simultaneously

Post by fth0 »

I'd suggest the following testing strategy:

1. In the VM configuration, re-enable System > Acceleration > Nested Paging for all VMs where you disabled it. Without it, you should be enthusiastic about a Windows 10 VM starting within 5 minutes. ;)

2. Provide only 2 vCPUs to each VM. Does the problem persist?

3. In the VM configuration of each VM, disable Display > Screen > 3D Acceleration. Does the problem persist?

4. In the VM configuration of each VM, enable Storage > Controller: AHCI > Use Host I/O Cache. Does the problem persist?
SebHellYea
Posts: 5
Joined: 2. May 2021, 20:49

How many CPU cores per VM when running 6 VMs on an Intel Core i9 10900X?

Post by SebHellYea »

hello,

my sys specs are:

CPU: Intel Core i9 10900X 10x 3.70GHz
Mobo: ASRock X299 Steel Legend
RAM: 256GB DDR4
HDD: 4TB SATA
GPU: 2GB MSI GeForce GT 1030
Host OS: Win 10 Pro

when running 6 VMs at the same time i dont have any issues with RAM at all but with CPU. when opening the task manager of each VM their CPU loads shows 100% right after booting the VMs. my CPU has 10 cores as you can see in the specs above but i think it can handle 20 processes. i set each VM's core number to 2 but that doesnt work since the CPU load is at 100% as mentioned. so should i rather set 1 core for each VM or 3?

thx
scottgus1
Site Moderator
Posts: 20965
Joined: 30. Dec 2009, 20:14
Primary OS: MS Windows 10
VBox Version: PUEL
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Re: How many CPU cores per VM when running 6 VMs on an Intel Core i9 10900X?

Post by scottgus1 »

Your CPU is a 10-core hyperthreaded https://ark.intel.com/content/www/us/en ... 0-ghz.html

Hyperthreads don't help Virtualbox much, so 10 is the host processor count.

Each VM "processor" is actually a thread on the host, so the host's cores aren't actually given to the VM, but the VM's thread per "processor" can be put on a core.

Generally, modern OS's like 2 cores. More "processors" in a VM slow down the VM, since the host OS has to schedule the threads, which slows down the threads. Adding processors to the VM only helps when there is software in the VM that can fill up the extra threads.

We don't know what OS's you're running in the VMs, and some OS's, like Windows, hit the disk and CPU hard for a bit after installation or bootup or update-checking or AV-scanning. 2 processors per VM and 6 VMs means 12 threads, on a 10 thread CPU, aside from the host OS needs, means something will have to slow down.

What happens when you let all 6 VMs running and sit overnight?
scottgus1
Site Moderator
Posts: 20965
Joined: 30. Dec 2009, 20:14
Primary OS: MS Windows 10
VBox Version: PUEL
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Re: Virtual Box gets extremely slow when running 6 VMs simultaneously

Post by scottgus1 »

Merged to bring identical-ish topics by same poster together.

See above comments.
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