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I would like to use more than one CPU to run Ubuntu 14.04 (Trusty Tahr) 32-bit in VirtualBox, but when I stop the machine and go in Settings → System → Processor, the processor(s) slider is grayed out as you can see in the screenshot image. How can I enable this feature?
Host OS: Windows 10 Pro 64-bit
Guest OS: Ubuntu 14.04 32-bit
VirtualBox: Version 5.1.22 r115126
Processor: Intel(R) Core(TM) i7-3770 CPU @ 3.40 GHz (8 CPUs), ~3.4 GHz
PS: My problem in the first instance is that the Ubuntu virtual machine is extremely slow and I would like to improve the performance, so any suggestion for that would also be welcome.
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To enable more than 1 CPU in your VM the following settings are needed in addition: 64-bit virtual guest hardware in General settings tab (for 64-bit guests) Enable I/O APIC in the Motherboard settings tab. Enable hardware virtualization (VT-x/AMD-V) in the Acceleration tab.
A single virtual machine can be assigned up to 240 virtual processors and 12 TB of memory. When creating such large virtual machines, memory from multiple NUMA nodes on the host system will likely be utilized.
The maximum number of processor cores that can be assigned to a single VM is 768 in vSphere 7.0 Update 1. A virtual machine cannot use more CPU cores than the number of logical processor cores on a physical machine.
That name is then similar to AMD-V. If you still have a problem with your VirtualBox not giving you an option to use multiple CPUs then you will most probably have to check if Hyper-V is installed in the "Turn Windows Features on or off". Which you might need to disable in order to use multiple CPU cores.
Click the "Processor" tab at the top of the window. Drag the slider next to "Processor (s)" to the right until the value matches the number of processors or processor cores installed in your computer. Drag the slider next to "Execution Cap" to the right until the value reads "100." This allows VirtualBox to use all of your processor's resources.
Is it a bad idea to assign more virtual CPU cores than a number of physical CPU cores as the following warning suggests (simply using all 8 virtual cores of 4 physical core CPU for instance): More virtual CPUs are assigned to the virtual machine than the number of physical CPUs on the host system (4).
I fixed it by : Stop virtual machine or exit. Launch VMWare --> Select machine -->Click System --> Click Processor --> Change number processors. Start Virtual Machine. Earlier std::thread::hardware_concurrency () from standard thread returned 1, but, after changes it returns the number of CPU's on the settings of Virtual Machine.
To increase performance you need to increase RAM and to use more than one CPU you need to enable "Virtualization technology" in the BIOS. Go to your BIOS options and search for "Virtualization technology" under "System settings" or similar. This is either called Intel-Vi-D or Intel-Vi with AMD processor. That name is then similar to AMD-V.
If you still have a problem with your VirtualBox not giving you an option to use multiple CPUs then you will most probably have to check if Hyper-V is installed in the "Turn Windows Features on or off". Which you might need to disable in order to use multiple CPU cores.
Some computers still might have no function towards virtualization use of multiple cores. That can be old computer models or more specific laptop computers. In some, you might need to check if there is a new BIOS version available for your computer.
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