1803543 - PreferenceRead markers are difficult to use in the profiler front-end

Status: RESOLVED FIXED

(Core :: Gecko Profiler, task, P1)

Description

[Florian Quèze [:florian]]

Two issues:

• no way to filter by preference name in the Marker Chart
• no way to see the list of accessed preferences in the Marker Table, as all preferences are just shown as "PreferenceRead"

Example profile: https://share.firefox.dev/3VuCegk
Example profile with the fix: https://share.firefox.dev/3EW1RPZ

Comment 1

[Florian Quèze [:florian]]

Attachment: Bug 1803543 - Improve the PreferenceRead marker schema to make the marker table show the name and value of the preferences, r=canaltinova.

Comment 2

[Markus Stange [:mstange]]

Are you using these markers for debugging? They were added at a time when people thought preference reads were a performance problem, which was incorrect. So I thought we might be able to remove these markers (and the profiler feature).

Comment 3

[Florian Quèze [:florian]]

(In reply to Markus Stange [:mstange] from comment #2)

Are you using these markers for debugging?

Yes, I used them for debugging today. (But that was probably the first time; or I would have been annoyed by the schema earlier.)

I thought we might be able to remove these markers (and the profiler feature).

I agree that this feature doesn't make a lot of sense, and I would like the list of features to be shorter. But I figured if we keep this code in our tree it could as well work reasonably well.

For the debugging use case, using MOZ_LOG might be good enough, but I couldn't find a log module related to preference access when I searched today.

Or if we were confident that the overhead is small enough, we could just have these markers by default. Seeing which preferences are read often gives a hint about which code ran, and how its behavior could be affected.

Comment 4

[BugBot [:suhaib / :marco]]

There's a r+ patch which didn't land and no activity in this bug for 2 weeks.
:florian, could you have a look please?
If you still have some work to do, you can add an action "Plan Changes" in Phabricator.
For more information, please visit auto_nag documentation.

Comment 5

[Florian Quèze [:florian]]

(In reply to Release mgmt bot [:suhaib / :marco/ :calixte] from comment #4)

There's a r+ patch which didn't land and no activity in this bug for 2 weeks.
:florian, could you have a look please?

Most of the patch is obsolete after the changes made in bug 1803751. I updated the patch to keep the marker table improvement, which is the only thing that isn't fixed yet.

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/571ed83f3984
Improve the PreferenceRead marker schema to make the marker table show the name and value of the preferences, r=canaltinova.

Comment 7

[Sandor Molnar[:smolnar]]

https://hg.mozilla.org/mozilla-central/rev/571ed83f3984