963499 - (jank-watcher) Implement a jank watcher to display event loop lags in Firefox OS's Developer HUD

Status: RESOLVED FIXED

(DevTools Graveyard :: WebIDE, defect)

Description

[Jan Keromnes [:janx]]

As a follow up to bug #960933, implement a JS jank watcher using bug #962511's devtools actor to display jank information in Firefox OS's devtools layers.

Comment 1

[Jan Keromnes [:janx]]

Attachment: Implement a JS jank watcher to display jank info in Firefox OS's devtools layers. r=vingtetun

Comment 2

[Jan Keromnes [:janx]]

Attachment: Implement a JS jank watcher to display jank info in Firefox OS's devtools layers. r=vingtetun

Comment 3

[Jan Keromnes [:janx]]

Attachment: Implement a JS jank watcher to display jank info in Firefox OS's devtools layers. r=vingtetun

Comment 4

[Jan Keromnes [:janx]]

Attachment: Implement a jank watcher to display event loop lags in Firefox OS's Developer HUD. r=vingtetun

Comment 5

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

Comment on attachment 8375855 [details] [diff] [review]
Implement a jank watcher to display event loop lags in Firefox OS's Developer HUD. r=vingtetun

Review of attachment 8375855 [details] [diff] [review]:
-----------------------------------------------------------------

R+ with one nit.

::: b2g/chrome/content/devtools.js
@@ +396,5 @@
> +        app.display();
> +      }
> +    }
> +
> +    this._active = value;

Move this one upper. Closer to the top of the method.

Comment 6

[Jan Keromnes [:janx]]

Attachment: Add a JS jank watcher to the Developer HUD. r=vingtetun

Comment 7

[Jan Keromnes [:janx]]

Attachment: Implement a jank watcher to display event loop lags in Firefox OS's Developer HUD. r=vingtetun

Comment 8

[Jan Keromnes [:janx]]

Attachment: jank.png

Comment 9

[Jan Keromnes [:janx]]

After playing with it, I decided to show the number of milliseconds instead of a jank count, much more useful that way. Also I find the actor threshold to be very low, thus tracking janks produces a lot of logs in ADB!

Comment 10

[Jan Keromnes [:janx]]

Comment on attachment 8375861 [details] [diff] [review]
Implement a jank watcher to display event loop lags in Firefox OS's Developer HUD. r=vingtetun

(keeping Vivien's r+)

Comment 11

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

(In reply to Jan Keromnes [:janx] from comment #9)
> After playing with it, I decided to show the number of milliseconds instead
> of a jank count, much more useful that way. Also I find the actor threshold
> to be very low, thus tracking janks produces a lot of logs in ADB!

I thought I landed something which is 100ms by default but I landed something else :(

I will try to fix bug 968237 as soon as I can in order to unlock this feature.

Comment 12

[Jan Keromnes [:janx]]

(In reply to Vivien Nicolas (:vingtetun) (:21) from comment #11)
> I will try to fix bug 968237 as soon as I can in order to unlock this
> feature.

Well, technically this feature isn't blocked on bug #968237, and I'm not sure it should be blocked on bug #969827 either. The current situation with a threshold >=20ms is that you see a lot more updates and logs, but it's still useful.

I suggest we don't block on those bugs and land now. Does that work with you Vivien?

Comment 13

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

(In reply to Jan Keromnes [:janx] from comment #12)
> (In reply to Vivien Nicolas (:vingtetun) (:21) from comment #11)
> > I will try to fix bug 968237 as soon as I can in order to unlock this
> > feature.
> 
> Well, technically this feature isn't blocked on bug #968237, and I'm not
> sure it should be blocked on bug #969827 either. The current situation with
> a threshold >=20ms is that you see a lot more updates and logs, but it's
> still useful.
> 
> I suggest we don't block on those bugs and land now. Does that work with you
> Vivien?

I'm fine to land it as if. People are still able to configure the interval in the meantime using MOZ_INSTRUMENT_EVENT_LOOP_THRESHOLD and MOZ_INSTRUMENT_EVENT_LOOP_INTERVAL in system/bin/b2g.sh if they need to tweak it until the pref has landed.

Comment 14

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/integration/fx-team/rev/40c7df94ad77

Comment 15

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/40c7df94ad77

Comment 16

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

I add to rebase the Gaia patch. Here is the changeset https://github.com/mozilla-b2g/gaia/commit/1a3d4629fb59c5b1e63e158b05777fd1c9c11a80

Comment 17

[Jan Keromnes [:janx]]

Thanks for rebasing :)

Comment 18

[Jan Keromnes [:janx]]

Mike, I'm curious about those whiteboard values, what are they for?

Comment 19

[Mike Lee [:mlee]]

Hi Jan,

We use those whiteboard values to populate our agile view, scrumbugs: https://scrumbu.gs/p/fxos-perf/

c=<component>, a performance-specific categorization (e.g. memory, power)
p=<point-value>, a value from 1 - 5 indicating Level Of Effort to fix this issue.
s=<sprint-name>, usually only used for bugs resolved before being added to a sprint.
u=<release/device>, used to indicate which release(s) or this is for (e.g. 1.3, 1.4, tarako) usually set when an issue is marked as a blocker.

Mike

Comment 20

[Jan Keromnes [:janx]]

Thanks Mike!