807309 - Compiling browser.js takes 90ms on first load

Status: RESOLVED INCOMPLETE

(Firefox for Android Graveyard :: General, defect)

Description

[Benoit Girard (:BenWa)]

This is measured on a Galaxy Nexus so this is likely slower elsewhere.

How can we mitigate this? Simply breaking up browser.js will likely increase the total compile time. Can we divide browser.js into pieces that can be loaded after?

http://people.mozilla.com/~bgirard/cleopatra/?report=439a965571b0283876e8d75722d7a370b5b49c52

Comment 1

[(no longer active)]

Michael, if I'm reading this profile correctly, we are indeed parsing browser.js, which should not happen if the startup cache is being used (right?).  Do we use the startup cache on mobile?

Comment 2

[Benoit Girard (:BenWa)]

I need to confirm the numbers above. I had done a rebuild so it wasn't a new profile but a different APK. Lets wait until I can confirm this across a few runs.

Comment 3

[Benoit Girard (:BenWa)]

I grabbed a few profiles without pushing a new APK and this in fact goes away so this is a problem that only happens when upgrading.

Comment 4

[Benoit Girard (:BenWa)]

Here's a profile of a subsequent load:
http://people.mozilla.com/~bgirard/cleopatra/?report=a58acc50c3f9dcf6c64b935d8d76077305bd2692

Comment 5

[Michael Wu [:mwu]]

(In reply to Ehsan Akhgari [:ehsan] from comment #1)
> Michael, if I'm reading this profile correctly, we are indeed parsing
> browser.js, which should not happen if the startup cache is being used
> (right?).  Do we use the startup cache on mobile?

Startup cache should be used on mobile, but we currently don't pregenerate startup caches for crosscompile builds so it has to be compiled on new profiles or when the startup cache is invalidated for whatever reason.

Comment 6

[Mike Hommey [:glandium]]

(In reply to Michael Wu [:mwu] from comment #5)
> Startup cache should be used on mobile, but we currently don't pregenerate
> startup caches for crosscompile builds so it has to be compiled on new
> profiles or when the startup cache is invalidated for whatever reason.

xulcache is not generated at build time anyways, and browser.js, being loaded from chrome, is xulcache, not jsloader cache.

Comment 7

[BMO Automation]

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