Clarification on "Include in memory balancing" checkbox

[brenda...@gmail.com]

I did not find any reference to this flag in qvm-prefs. From the source code it appears this checkbox mostly does some automatic enabling/disabling of meminfo-writer checkbox in the service tab.

Is that primarily what it does?

This checkbox is the equivalent of $ qvm-service [vmname] meminfo-writer on/off (well almost, ignoring default conditions)?

Thanks,
Brendan

[Tim W]

Thats what I also thought but mybknowledge base is merger in this area. I am sure it could be answered quickly on the devel list.

[brenda...@gmail.com]

On Thursday, February 8, 2018 at 2:33:02 PM UTC-5, Tim W wrote:
> Thats what I also thought but mybknowledge base is merger in this area. I am sure it could be answered quickly on the devel list.

The "Include in memory balancing" checkbox appears to be designed to resolve a bit of multi-variable issue: how memory settings and memory balancing settings are displayed/stored/implemented.

e.g. if I want a VM to have a static memory amount (and also not expect memory things to be adjusted by qubes memory management while the VM is running), I need to both set min and max to the same as well as explictly disable meminfo-writer.

The "Include in memory balancing" checkbox polices the memory settings and *almost* polices the meminfo-writer setting, but there's a coverage gap if meminfo-writer isn't already on the services list. To close the circle, the "Include in memory balancing" checkbox should also add meminfo-writer service to the service list of services and then explicitly disable meminfo-writer (if the meminfo-writer service is missing when the "Include in memory balancing" checkbox was checked).

Does that make sense?

Brendan

[Tim W]

Yes mostly that makes sense. I am not cealr on your last part but may be reading it incorrectly. If checking the box should automatically check to ensure mem is included in the services list and if not add it then why would it also disable mem if it does not find it in the services list? Seems like its staying to do two opposing actions when running the checklist add it if its not found but also disable it if its not found?

Cheers.

Tim

[brenda...@gmail.com]

Generally: the listing of a qubes service in the services tab allows you to
override the default setting for that service. Some services are enabled by default, so if they are not listed they are still enabled. This also applies to the qvm-service tool.

e.g. meminfo-writer is by default *enabled* on all VMs with the exception of NetVMs (or for R4.0, this would be a VM that "provides network"). So if it is not listed, it is *enabled*.

Reference #1:

From: https://www.qubes-os.org/doc/vm-interface/
[[/qubes-service/SERVICE_NAME - subtree for VM services controlled from dom0
(using qvm-service command or Qubes Manager). One of 1, 0. Note that not every
service will be listed here, if entry is missing, it means “use VM default”.
List of currently supported services is in qvm-service man page]]

(useful since it points to the man page for qubes-service below...)

Reference #2:
man qvm-service says (manual copy-paste):
meminfo-writer
Default: enabled everywhere excluding NetVM

So, again: if under services, meminfo-writer is *not listed*, it is *ENABLED*.

Brendan

[Tim W]

Got it thanks for the further explanation. I was not understanding it correctly. Makes sense now.

Cheers,

Tim