qemu-system-aarch64 memory balloons to 20GB, even though explicitly set to 12GB

[jdolitsky]

Description

In my lima config, I set memory explicitly to 12GiB.

limactl list shows this:

NAME     STATUS     SSH                ARCH       CPUS    MEMORY    DISK      DIR
myenv    Running    127.0.0.1:59699    aarch64    6       12GiB     100GiB    /Users/jdolitsky/.lima/myenv

After running a bunch of containers in the VM, the mac "Activity Monitor" shows the memory of qemu-system-aarch64 to be roughly 20 GB (see screenshot below):

This has been confirmed on 3 separate machines (all M1 Macs), running lima version 0.8.2

[jdolitsky]

Just tested on new release (0.8.3), and the issue still exists

[abiosoft]

@jdolitsky that is not the actual memory being used, right-click on the any of the column title and include Real Memory column.

[jdolitsky]

@abiosoft - thanks for sharing that. Found this answer which tries to explain the differences in the memory fields:
https://apple.stackexchange.com/a/107

Here's what I get with a 16GiB lima VM, and all memory columns active:

Still, none of those numbers appear to equal exactly 16, so I'm still not sure. I even considered the difference between GiB and GB (16 GiB = 17.179869184 GB).

[AkihiroSuda]

Still, none of those numbers appear to equal exactly 16, so I'm still not sure.

Can’t equal exactly, because the QEMU process itself has to consume some memory in addition to the VM’s memory

[deviantintegral]

I'm seeing something similar, but with x86_64 (running on Intel). In my case, the VM is set to 16GB. I think large amounts of IO can trigger it. For example, I have may GB of Docker images exported, and when I load them with docker load by the time it's done qemu-system-x86_64 will be using ~30GB of Real Memory.

[jdolitsky]

This might make a lot of sense (the IO). We are running a registry on the VM and publishing several images to it.