Selecting logical CPUs for your Home Assistant OS VM on Unraid /Or General VM both Appliciable

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When selecting logical CPUs for pinning in Unraid, it’s generally recommended to choose logical CPUs that are on the same physical core or within the same NUMA node to reduce latency and improve performance. However, it also depends on your specific workload and the overall CPU usage of your system.

Here’s a general approach to selecting logical CPUs for your Home Assistant OS VM:

  1. Identify Core Pairings: If you have a CPU with hyper-threading, each physical core will have two logical CPUs. For example, if CPU 0 and 1 are paired, then CPU 2 and 3 might also be paired, and so on.

  2. Avoid High-Usage Cores: Try to avoid logical CPUs that are heavily used by other processes or VMs. You can check the CPU usage in the Unraid dashboard to identify which CPUs are less utilized.

  3. NUMA Nodes: If you have a multi-socket system or a CPU with multiple NUMA nodes, ensure that the logical CPUs you select are within the same NUMA node to avoid performance penalties.

  4. Consistency: Keep the CPU pinning consistent to avoid unnecessary context switching and performance degradation.

Given your current selection of CPU 2 and 18, it seems like these CPUs might be from different physical cores or NUMA nodes. If you choose CPUs 2 and 3, they are likely to be hyper-threads of the same physical core, which might give better performance for a VM like Home Assistant OS.

To make a more informed decision, you can check the logical-to-physical CPU mapping on your system. Here’s how you can do it:

  1. SSH into Unraid:
    Open an SSH session to your Unraid server.

  2. List CPU Pairings:
    Use the following command to list the CPU pairings:

    lscpu -e

    This will show you the mapping of logical CPUs to physical cores.

  3. Review the Output:
    Identify which logical CPUs are paired together.

For example, if lscpu -e shows something like this:

CPU NODE SOCKET CORE L1d:L1i:L2:L3 ONLINE MAXMHZ    MINMHZ
0   0    0      0    0:0:0:0       yes     3500.0000 800.0000
1   0    0      1    1:1:1:1       yes     3500.0000 800.0000
2   0    0      0    0:0:0:0       yes     3500.0000 800.0000
3   0    0      1    1:1:1:1       yes     3500.0000 800.0000
...

In this example, CPUs 0 and 2, and CPUs 1 and 3 are pairs. Thus, selecting CPUs 2 and 3 might be a good choice for pinning.

Steps to Pin CPUs in Unraid:

  1. Open the VM Configuration:
    Go to the VM tab in Unraid and edit the Home Assistant OS VM configuration.

  2. CPU Pinning:
    Set the CPU pinning to the chosen logical CPUs (e.g., 2 and 3).

  3. Save and Reboot:
    Save the configuration and reboot the VM for the changes to take effect.