Use Available memory instead of Free to compute system.memory.usage:free

[ItsLastDay]

Description: Fixes a bug where system.memory.usage:free has strange values

Link to tracking Issue: #24031

Testing: Not yet tested

Documentation: nothing added. What should I add?

[crobert-1]

You'll need to add a changelog entry for this change since this will have user impact.

[crobert-1]

From the documentation you referenced it looks like this is the right variable to use.

It would be really good to have a comparison before and after the change to confirm that the new metric being used is what's expected, and charts (like you shared in your original issue) make sense with the new values.

[dmitryax]

Please look at this issue first #7417 . I don't believe we agreed on this solution. The work on that issue got stuck, but there is a System semantic conventions WG started recently, so it's a good chance to come to a solution finally. Please feel free to join open-telemetry/opentelemetry-specification#3556. There are weekly calls on Web 8:30 AM PST.

[github-actions]

This PR was marked stale due to lack of activity. It will be closed in 14 days.

[ItsLastDay]

Thank you Dmitrii for information! I'll close this PR and my issue, and will continue in #7417.

I see that Braydon (who's also from Google) expressed interest in helping with #7417 in open-telemetry/opentelemetry-specification#3556 (comment). So I hope I'll personally be able to skip the WG meetings, and instead provide all the context asynchronously through comments.