virtualbox.org

The next gen Intel CPU will have performance cores and efficient cores. When create VM with 4 core/thread, how does the VB choose among performance and efficient cores? Will it be fixed at VM creation, or can it dynamically switch between the two types of cores?

I personally have never heard of this. If the "next-gen" means these devices are not out yet, it could be the devs haven't had a chance to test. We'll have to wait until this concept becomes mainstream to see how the devs will set Virtualbox to handle it.

scottgus1 wrote:I personally have never heard of this.

You can read about the basics in Intel's Alder Lake Combines 'Performance' and 'Efficiency' CPU Cores on One Chip.

reader wrote:When create VM with 4 core/thread, how does the VB choose among performance and efficient cores? Will it be fixed at VM creation, or can it dynamically switch between the two types of cores?

To give you an example from today, VirtualBox creates 42-ish threads for a VM with 2 vCPUs, and lets the host OS decide on which physical CPU cores/threads to run them. As far as I understand the known details of the Intel Thread Director (Intel Architecture Day 2021: Alder Lake, Golden Cove, and Gracemont Detailed), the physical CPU and the host OS will decide the core/thread selection themselves.

Does anyone have a new perspective on this, now that 12700 has been out for a while and 12900 is coming out? Trying to decide on intel or AMD for a box that will mostly be for VMs and sometimes gaming. The E cores run slower than the P cores, wondering what the overall impact is on VMs with VBox. Will I see much difference between AMD (12 cores)/24 threads vs Intel (8P+8E cores)/24 threads when running several VMs at once (database server, web server, etc)?

fth0 wrote: To give you an example from today, VirtualBox creates 42-ish threads for a VM with 2 vCPUs, and lets the host OS decide on which physical CPU cores/threads to run them. As far as I understand the known details of the Intel Thread Director (Intel Architecture Day 2021: Alder Lake, Golden Cove, and Gracemont Detailed), the physical CPU and the host OS will decide the core/thread selection themselves.

I can't see that changing. I would not expect VirtualBox (or any other app) to get involved at that level. CPU queues and priority scheduling are pretty low-level OS stuff.