Disable dynamic memory assignment on Windows

[twhite0]

Thank you for the local 4.x OpenShift environment. I've been using it over the past couple days to review Tekton/Openshift Pipelines and its working great! One small thing I've uncovered that I thought I'd surface.

General information

• Windows
• Hyper-V
• crc setup run

CRC version

version: 1.0.0-beta.3-4.1.11+e97bf65

CRC status

CRC VM:          Running
OpenShift:       Running (v4.x)
Disk Usage:      14.69GB of 32.2GB (Inside the CRC VM)
Cache Usage:     11.08GB
Cache Directory: C:\Users\[user]\.crc\cache

CRC config

- bundle                             : C:\Users\[user]\.crc\crc_hyperv_4.1.11.crcbundle
- cpus                               : 4
- memory                             : 8192
- nameserver                         :
- pull-secret-file                   :
- vm-driver                          : hyperv
- warn-check-bundle-cached           : true

Host Operating System

OS Name:                   Microsoft Windows 10 Pro
OS Version:                10.0.18362 N/A Build 18362
OS Manufacturer:           Microsoft Corporation
OS Configuration:          Standalone Workstation
OS Build Type:             Multiprocessor Free

Steps to reproduce

1. fresh download of crc.exe along with pull-secret file
2. PowerShell run as admin `.\crc.exe start -p .\pull-secret
3. Upon startup of Openshift Starting OpenShift cluster ... [waiting 3m]. The memory usage of the VM will continue to creep higher until the machine is unusable.

Expected

Would expect the Hyper-V VM to be limited to 8GB of RAM.

Actual

It looks as if on my machine the Dynamic Memory section of the crc image was turned on and the Maximum RAM setting was established at 1TB. This was well over what I have installed on my machine (16GB).
I'm unsure why the memory was creeping higher and higher. Once I spotted the max memory setting and lowered it to 8GB everything has been running great.

[gbraad]

We left dynamic memory assignment as we see no problem with the behaviour for the average user. Wh n more resources are needed, they are assigned without need to interfere .
You are free to modify the VM.

However, do you think this should be disabled?
Resource usage will be reviewed soon wish as part of OpenShift itself. We will keep an eye on this and make sure our use case is also considered.

[twhite0]

Thanks for the response @gbraad.

We left dynamic memory assignment as we see no problem with the behaviour for the average user.

I'm not sure if I fit the "average user" category 😄. It was my first usage of Hyper-V & crc. It didn't take long once my machine slowed to look the resource usage and track down the Dynamic memory assignment area.

However, do you think this should be disabled?

No. In theory it makes sense. While I was able to quickly figure things out, my user experience was thrown off a bit with the CRC config being set to 8GB however the dynamic Max was set well above that.

[gbraad]

for me it usually starts to settle at about 11 or 12GB (the machine has 32GB available). I have to admit, this is a lot, but with fixed memory we end up having other issues.

The ideal would be to put OpenShift 4.x on a diet, but these are on-going discussions ... There is another issue that discusses them, just at the moment unable to track it down.

[tsmaeder]

One might argue about whether dynamic memory should be the default or not, but once I've told crc to use a certain amount, I would not expect it to use more. To quote the crc start --help:

 -m, --memory int                MiB of memory to allocate to the OpenShift cluster (default 8192)

Currently, this help text is not correct, since the default is not 8192MiB, but "dynamic, max 1TB".
If "dynamic" is the default, the behaviour should really not bog down the host machine. Right now, I end up with my 32Gb being 90% full with -m 16000.

[gbraad]

This can be disabled on a per-VM basis.

You can also disable this with:

PS> Set-VMMemory crc -DynamicMemoryEnabled $false

[jeffmaury]

I'm using it with my CRC VM. Let see if this is working well

[gbraad]

the problem is partially due to how OpenShift/K8s aggressively deals with memory use. All my VMs run on a 24GB T460p work laptop (fedora, rhel and CRC) at the same time. All enabled with dynamic memory.

Want more feedback about this... before disabling. I could consider adding a default max memory option... as this would not remove the current behaviour, but restrict it ?

For example:

PS> Set-VMMMemory crc -MaximumBytes 12GB

to restruct to a mamximum of 12GB

[jeffmaury]

Docker Desktop is not using Dynamic Memory !. I will report if I found any issue with my CRC after a while.

[tsmaeder]

@gbraad I have restricted the memory on my crc VM to a reasonable size and that works well. However, I still think the default is wrong: hogging most of my machine's memory when I tell the CLI explicitly how much memory I'd like it to take is unfriendly, IMO. I think I am a pretty good stand-in for your user community and I would not have expected that at all.

[gbraad]

If this gets changed a new documentation entry is needed to deal with this as previously, Windows users did not need to change the memory usage. The current suggestion for the hypervisors is to do `crc delete, crc start` to handle this (as it works across all hypervisors. or a platform specific entry is needed to handle this @kowen WDYT? I guess this should be added as an entry to the Release Notes and perhaps a topic to deal with this ? As currenrtly, users that develop a large application did not have to modify the default value when starting CRC as the memory usage scaled on demand. Troubleshooting? For consistency it is best to 'fix' this. Note: it is not about changing this to fixed memory, but changing the default behaviour.