Can't assign more than 8 cores to Win10 64 guest? (#17898)

[NexusPenguin]

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ModEdit; related ticket: #17898: Can Not Assign More Than 8 Processors to Windows 10 Guest

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Hi there,

I assume this has been discussed already, but I could only find really old posts about it.

So here's the thing : I'm running a decent machine (Gigabyte MD80-TM0 motherboard - 2 X Intel Xeon 14 cores/28threads - 110GB RAM - Plenty of storage - Radeon RX460) with Linux Mint 18.3 (all upgrades done to date).

I have downloaded latest VirtualBox version and installed it.

I have a genuine .iso file of Windows 10 (I can choose Pro or Home version...) in 64 bit.

I can install it with all settings to default. Not a problem...

BUT : as soon as I increase the number of CPU's assigned to that machine to anything above 8 CPU's, virtual machine refuses to boot
It boots into 8 CPU's but is really slow then...

Is this a known problem that is being worked on ? Is there a workaround to circumvent this at the moment ? Am I doing something terribly wrong ?

Thanks for your answers.

Regards.

FRED

[mpack]

Please provide a VM log file. With the VM fully shut down, right click it in the GUI. Select "Show Log" and save "VBox.log" (no other file) to a zip file. Attach the zip here.

[SmartUser]

I have the very same problem trying to use 32 cores on Intel Xeon E5-2695 v4

[mpack]

I have the very same problem trying to use 32 cores on Intel Xeon E5-2695 v4

Strange. According to Intel, the E5-2695 v4 only has 18 cores, but the log reports 36 (72 threads). Do you actually have two of these CPUs on the board?

If you can't assign 32 cores, how many can you assign? Have you confirmed 8, per the topic title?

[andyp73]

00:00:05.586188 CPUM: Logical host processors: 72 present, 128 max, 72 online, online mask: ffffffffffffffff
00:00:05.586193 CPUM: Physical host cores: 36

This would suggest so and the Supermicro product definitely supports it.

-Andy.

[mpack]

Obviously this is not something I can test myself (my PCs are quad core), but I vaguely recall that the VirtualBox limit is 32 or 128 (*), perhaps depending on the selected VM chipset (do NOT take that as a cue to mess with the chipset selection).

Are you saying that VirtualBox rejects the 32 cores selection, or simply, like the OP, just that the VM runs very slow? -- Never mind, that's in the log. The VM runs fine until it starts initializing graphics 8 seconds in, then nothing else until the VM is shut down 4 minutes in. I don't see any obvious errors in the VM config.

And like the OP, your VM has no problem if you stick to 8 cores?

(*) Edit. Just found it in the user manual (3.5.2). The limit is 32 cores, no mention of chipset.

[SmartUser]

Yes I have two CPUs with 18 cores each which makes 72 logical cores total. But anyway I want to have VM with around 20-30 cores not more.
I confirm that with 8 cores it is working as said in the topic title, but If I try to increase the number it gets stuck. I treid with 16 cores and after waiting 1 hour just force shutdonwed the machine.

I don't need any GPU on the VM so I run it with 128 mb Vram which is in the configuration. I didn't try to reduce the Vram and check what will happen, but maybe will do these days if you think this can help.

NOTE: When the machine ran with 8 cores it was extremly slow, but if I run with 4 or less cores it is getting faster. I'm not sure if this has anything to do with the current issue but just a note.

[mpack]

Looking around, I notice that all instances I can find (e.g. here) are on host motherboards using multiple CPUs (e.g. dual Xeon), including both examples in this thread. Perhaps it's time to raise a new ticket, or reopen that one.

Yes I have two CPUs with 18 cores each which makes 72 logical cores total.

Um, just on a point of pedantry, IMHO there is no such thing as a "logical core". You have a 36 core machine. The word core refers to a piece of physical silicon, and you specifically use it when you want to talk about those bits of silicon rather than logical processors.

It's a minefield - the only related term more abused than core is CPU (how can you have more than one "central" processor?).

[jagdpanther]

Was this issue resolved? I am having the same problem:

I just built a new Linux (Gentoo) system based on a SuperMicro C9X299-PG300 and an Intel i9-7940X (14-core, 28 thread). I copied over my Windows 10 VirtualBox guest VM from the old system (Intel i7 8-core) to the new system. The Virtual Box guest boots without issue using the old settings (8-cores). However, if I shut down the VM and change the settings to a higher core count (I have tried 12 and 14 cores), the VM does not progress very far into its boot: I see a blue background and the windows icon. None of the VirtualBox activity icons at the bottom of the Guest window are active: all dark. That is it. There is one Virtual Box process that continues to run at 100% cpu usage until I kill the VM. In the VirtualBox log the relevant part is:

Code: Select all

00:00:03.569172 VMMDev: Guest Log: BIOS: Boot : bseqnr=1, bootseq=0032
00:00:03.570686 VMMDev: Guest Log: BIOS: Booting from Hard Disk...
00:00:03.872720 Display::handleDisplayResize: uScreenId=0 pvVRAM=00007f2f74000000 w=1024 h=768 bpp=24 cbLine=0xC00 flags=0x0
00:00:03.872802 GUI: UIFrameBufferPrivate::NotifyChange: Screen=0, Origin=0x0, Size=1024x768, Sending to async-handler
00:00:03.872885 GUI: UIMachineView::sltHandleNotifyChange: Screen=0, Size=1024x768
00:00:03.872897 GUI: UIFrameBufferPrivate::handleNotifyChange: Size=1024x768
00:00:03.872908 GUI: UIFrameBufferPrivate::performResize: Size=1024x768, Directly using source bitmap content
00:00:04.610473 GIM: HyperV: Guest OS reported ID 0x1040a0000271b
00:00:04.610490 GIM: HyperV: Open-source=false Vendor=0x1 OS=0x4 (Windows NT or derivative) Major=10 Minor=0 ServicePack=0 Build=10011
00:00:04.610506 GIM: HyperV: Enabled hypercall page at 0x000000000020f000
00:00:04.610778 GIM: HyperV: Unknown/invalid hypercall opcode 0x8001 (32769)
00:00:04.610792 GIM: HyperV: Enabled TSC page at 0x000000000000c000 - u64TscScale=0xd3add100000000 u64TscKHz=0x2f3dc9 (3 096 009) Seq=1
00:00:04.610982 TM: Switching TSC mode from 'VirtTscEmulated' to 'RealTscOffset'
00:00:04.611068 GIM0: HyperV: Enabled APIC-assist page at 0x000000000000d000
00:00:04.614818 APIC0: Attempt to read reserved/unknown MSR (0x80e) -> #GP(0)
00:00:04.614825 IEM: rdmsr(0x80e) -> #GP(0)
00:00:04.614859 GIM: HyperV: Guest indicates a fatal condition! P0=0x1e P1=0xffffffffc0000096 P2=0xfffff80360406fd9 P3=0x0 P4=0x0
00:05:36.462561 GUI: Request to close active machine-window.

The "HyperV: Guest indicates a fatal condition!" does not look good.

Any suggestions on using more than "8-cores" on my VirtualBox Windows 10 guest?

[jtsillas]

I'm having the same problem. Windows 10. Max is 8 cores. The host machine is a Xeon with 72 threads running Windows Server 2012R.

[mpack]

There is no need to tell us the number of threads. The only relevant statistic is the number of available cores.

[whiterussiansp]

Having the same issue. Dual Xeon, Windows 10 guest, using 8 of 24 cores machine runs flawless. As soon as I go over 8 to any other number the VM hangs and will not boot. Any update?

[frg]

I think if you have a dual board just make sure you don't use more cores that one processsor has physical cores. Whity my old X5675 it would slow down when going over 6 and also hang with 8 I think. Seems to be Virtualbox doesn't like more than one Numa node aussuming it uses physical cores only.

[oizo]

Hi,

I had the exact same problem, Xeon Silver 4108 @ 1.80GHz x 32.
Host: Ubuntu 18.10
Guest: Windows 10 Enterprise

As soon as I assigned more than 8 cores to the virtual machine it wouldn't boot. Critical failure from HyperV as stated in the posts above.

I changed the paravirtualization interface from Default to KVM and now the system boots up with 16 cores. I don't know if I am losing performance by doing this.

[mpack]

I don't see how the choice of hypervisor API compatibility provided to the guest could affect the cores issue.