1340714 - Change the way responsiveness information is calculated for Gecko profiler samples

Status: RESOLVED WONTFIX

(Core :: Gecko Profiler, defect)

Description

[Markus Stange [:mstange]]

At the moment we calculate responsiveness times by submitting an event to the event loop (CheckResponsivenessTask) and checking how long it took between dispatch and processing. This tells us by how much the event loop is backed up for normal priority events.

With different event priorities, this value will become less meaningful.

Ehsan told me that what he usually is interested in is whether there are long-running single tasks that the event loop is busy with.

So I'm proposing we change the meaning of the "responsiveness" value to be, for each point of time, the time since we started processing the task that's currently running. This requires a bit more instrumentation in the event loop.
The disadvantage of this approach is that we won't notice that anything is wrong if the event loop is backed up with a very large number of very short running tasks.

Comment 1

[Gerald Squelart (he/him) (not at Mozilla since 2022-09-15)]

The responsiveness computation was changed in bug 1572337, so I don't think we'll tackle this bug here.