Question: Measurement of gunicorn.request.duration

[sitaram-manatal]

Hello,
I wanted to ask about how the metric gunicorn.request.duration measurement is implemented in Gunicorn. For example, when a request is forwarded to Gunicorn, it is recieved at time let's say t1. There might be some queuing/backlog due to high throughput scenario and request have to wait till time t2 until it is picked up by the worker to process and return the response at time t3.
Does the gunicorn.request.duration include the time between t3-t1 or it only includes t3-t2 ?
Let me know if there is any more appropriate forum to ask this question.

This is also related to the backlog metric itself is not being available Issue 2057 and Open PR

Thanks in advance.