GKE metering cost_with_unallocated_untracked

[alsyia]

Hi,

I have a question regarding the GKE Metering connector. What does the cost_with_unallocated_untracked metric represents? How is it computed? I took a look at the query but it's quite verbose.

I'm quite puzzled at how it's possible to track "unallocated/untracked" costs down to a specific combination of request and labels.

For example I get CPU request entries where the cost and the cost_with_unallocated_untracked are really different, and I'm not sure which one I should use.

Any explanation about this would be welcome :)

(Also, apologies if this is not the right place to ask)

Thanks!

EDIT:

Ok, I took some time to analyse the query.

First I don't understand the difference between unallocated_usage and breakdown_untracked_resource_usage. The only difference between these two tables is that the first one has been filtered on namespace="unallocated", but since they are both made from untracked_resource_usage in which all entries have namespace="unallocated", I don't really see the point. So I'm going to consider unallocated means the same thing as untracked in the following lines.

This being said, resource_usage.amount_with_untracked is just resource_usage.amount_with_untracked times a rate.
resource_usage.amount_with_untracked has the following formula:

resource_usage.amount_with_untracked = filtered_resource_usage_with_unused.amount + filtered_resource_usage_with_unused.allocate_unused + unallocated_usage.amount * (filtered_resource_usage_with_unused.amount / total_used.amount)

And of course, filtered_resource_usage_with_unused.allocate_unused is defined a few lines above like this:

  filtered_resource_usage_with_unused.allocate_unused = (filtered_resource_usage.amount / aggregated_resource_usage_by_resource_name.amount) * breakdown_untracked_resource_usage.amount

I somewhat understand allocate_unused; we take every resource (cpu/mem/networkEgress) we have not been able to track down to a specific reservation, and we split them between all reservations with a proportionality rule: each reservation (entry in filtered_resource_usage) gets a part of the untracked resources proportional to how much resource it reserved compared to the total reserved. (that's the quotient part).

So allocate_unused is a share of the unused (= untracked = not reserved) resources attributed to this particular reservation. (I find the term "unused" misleading, because they could very well be used, they just can't be tracked down to a reservation, which means a workload somewhere is exceeding it's request?)

Now if we look at resource_usage.amount_with_untracked, it's the sum of the real usage/reservation + the share of untracked usage attributed (so far so good), + another share of untracked usage, but this times the ratio used for the attribution is the share of the reservation in the total usage billed! That's a different way to attribute untracked usage, I guessed, but the resulting value doesn't really makes sense to me.

I guess I'm wrong somewhere (maybe about the "unallocated" part), because it looks to me like unallocated and unused are the same quantities, which doesn't make sense. And the resulting amount_with_untracked I don't understand either...