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How does VB choose performance/efficient cores

PostPosted: 24. Oct 2021, 20:29
by reader
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?

Re: How does VB choose performance/efficient cores

PostPosted: 24. Oct 2021, 20:37
by scottgus1
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.

Re: How does VB choose performance/efficient cores

PostPosted: 25. Oct 2021, 00:49
by fth0
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.