1566049 - extend AutoPhase to record the duration excluding its sub-phases.

Status: RESOLVED WONTFIX

(Core :: JavaScript: GC, enhancement, P3)

Description

[Yoshi Cheng-Hao Huang [:allstars.chh][:allstarschh][:yoshi]]

We have phaseTimes in AutoPhase to record the time spent for the specific phase,
https://searchfox.org/mozilla-central/rev/1097f59d0bc17f6f8f805325c2f607e60cf0d26b/js/src/gc/Statistics.h#342

We could figure out its own running time (excluding its sub-phases) by the table.

However the table is for the phases occured in this GC, imagine the following case:
A -> B1 -> C -> ~C -> ~B1 -> B2 -> ~B2 -> ~A
B1 and B2 are the same phase, however in B1 there's a sub-phase C running, whereas in B2 it doesn't have any sub-phase.

When we are trying to figure out how much time B1 spent on itself (not including C), we could use the phaseTimes to figure this out, however for B2 it will have problems, since B2 doesn't have any sub-phase.

So we need another bookkeeping to tell that B1 has a sub-phase and B2 doesn't, and calculate their own running time respectively.

Comment 1

[Yoshi Cheng-Hao Huang [:allstars.chh][:allstarschh][:yoshi]]

Attachment: Bug 1566049 - Part 1: keep track of child duration running on stack.

Comment 2

[Yoshi Cheng-Hao Huang [:allstars.chh][:allstarschh][:yoshi]]

Attachment: Bug 1566049 - Part 2: show duraion since the last same phase started.

Depends on D38319

Comment 3

[Yoshi Cheng-Hao Huang [:allstars.chh][:allstarschh][:yoshi]]

won't need for now