989263 - Reduce performance impact of the Developer HUD

Status: RESOLVED FIXED

(Firefox OS Graveyard :: Gaia::System, defect, P3)

Description

[Jan Keromnes [:janx]]

Currently, running Firefox OS with the Developer HUD active means that every frame being created will receive instrumentation in the form of devtools child actors (the following method is called on every frame with a manifestURL: http://dxr.mozilla.org/mozilla-central/source/toolkit/devtools/server/main.js#370-387).

Comment 1

[Jan Keromnes [:janx]]

To reduce the performance hit of the Developer HUD, it would be great to only load devtools actors when they are actually needed (e.g. to track errors, reflows, etc).

Comment 2

[Dave Huseby [:huseby]]

I'm tagging this so the perf team can track it under devtools category.

Comment 3

[Jan Keromnes [:janx]]

Measuring "App memory" is quite perf intensive, but bug 976024 introduced a much lighter "Unique Set Size" tracker.

Tracking "USS" rather than "App memory" is encouraged, because it is faster and covers all of an app's footprint (for example "App memory" doesn't track big resources like images). Bug 976024 tries to nudge HUD users in that direction by tracking USS by default when the HUD is activated.

Bug 1035396 tries to make USS tracking even faster/lighter.

Comment 4

[Jan Keromnes [:janx]]

Attachment: Reduce Developer HUD polling frequency for USS. r=21

Comment 5

[Jan Keromnes [:janx]]

Comment on attachment 8467754 [details] [diff] [review]
Reduce Developer HUD polling frequency for USS. r=21

The memory widget doesn't need to be updated very frequently. I found that reducing the poll frequency to .5Hz made USS monitoring's impact significantly less visible.

Comment 6

[Vivien Nicolas (:vingtetun) (:21) - (NOT reading bugmails, needinfo? please)]

Comment on attachment 8467754 [details] [diff] [review]
Reduce Developer HUD polling frequency for USS. r=21

Review of attachment 8467754 [details] [diff] [review]:
-----------------------------------------------------------------

LGTM. If we need to adjust it again, we should seriously think about creating a pref for it.

Comment 7

[Jan Keromnes [:janx]]

Thanks! A pref is an excellent idea, I'll keep that in mind.

Comment 8

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/integration/b2g-inbound/rev/6985f4896a10

Comment 9

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/6985f4896a10

Comment 10

[Jan Keromnes [:janx]]

(The HUD's performance impact has successfully been reduced in other bugs.)