Firefox Startup Performance – January 15

Happy 2010 everyone!

Top Startup Bugs

Estimated win	Bug #	Summary	Owner	Status	Notes
>10%	512584	Super fast paths for Components.classes and Components.interfaces	Taras Glek	in progress	Taras is traveling, says he’ll close it out when he returns.
>10%	525013	Investigate a more static build configuration of Firefox	Joel Reymont	in progress	Lots of progress! Joel has a patch for Mac and Linux working on the tryserver, and numbers to confirm a partial static build gets ~8% improvement on Mac, with no compat problems. Zach added a bunch of number crunching to validate Joel’s numbers. On the Windows front, Taras has a patch in progress now.
up to 25%	514083	Per-file HFS+ compression on Mac OSX 10.6	Joel Reymont	in progress	Conclusion is that we need to make this happen via the installer, as well as the updater, since modifying files results in decompression. Need to find an owner for this still.
TBD	520309	Startup cache: replacement for fastload cache	Ben Hsieh	in progress	Ben is looking into a perf regression that arose after some major changes.
TBD	503483	Turn on –enable-faststart for Firefox by default	Dietrich	needs testing	No update, need to test still. Maybe just push on Windows here.
TBD	513149	Speed up CSS parsing by using a machine generated lexer	Zack Weinberg	Zack’s blocked on other work	No update.Taras says about 6% of startup spent parsing CSS.

Other activity this week:

• I updated Mark’s patch in bug 507012 to trunk and ran it on Windows. Here is the ranked log and the stack view. From perusing this data, I filed bug 539997, bug 539991, bug 539869 and bug 539870.
• I’ve been working on bug 506471, to move FUEL out of the startup path, and also making a bunch of minor improvements and cleanup in that code.
• While I was gone, Rob Strong put up a great post about what JS components are in the startup path and how much time they take up.

Projects in a holding pattern:

• More investigation into Hunspell changes in bug 468799, possibly incorporating some changes Chrome made.
• Ryan Flint has a WIP patch to minify JS on bug 524858 that significantly reduces the size of shipped JavaScript files.
• JARification: David abandoned moving JS modules into a JAR file, since those files are fastloaded. However, since we want things like post-extension-install restarts to be fast, and those cause fastload cache invalidation, we might want to do things like this anyways. I filed a bug for the same treatment for components. These are lower priority, since they’re not the normal startup case. Follow along with all JAR-ification via the tracker bug.
• Startup Timeline: No updates, still not landed. Add [ft] in the whiteboard of your bug w/ the function names you want timed and David will generate it and update the bug.
• Static Analysis: No progress on bug 506128. David needs to file a bug with the final log of named-yet-uncalled functions.
• Dirty Profile Testing: No progress. We have a list of test scenarios, still need to file bugs for each, generate Talos config patches and profile data, and then move it into Rel-Eng territory. Also, need to get a separate Tinderbox tree, since it’s going to cause a bazillion new columns.
• Joel Reymont noted in bug 513076 that there are serious drawbacks to getting our libraries in the dyld shared cache on Mac, so has deprioritized that work.

As usual, more details and links are available on the project wiki, and we’re available to answer questions in #startup on irc.mozilla.org.

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