Firefox Startup Performance Weekly Summary

Current numbers are available on the Performance Snapshot page. Thanks to Chris Atlee for deploying it to the graph server. The snapshot is updated every 5 minutes with fresh data from Talos.

Summary, relative to Firefox 3.5:

• Warm startup: For Mac, 26% better on 3.6 and 31% better on 3.7. For Windows, 4% and 7%. Flat on Linux.
• Cold startup:  For Mac, 22% better on 3.6, 23% better on 3.7. For Windows, not measuring yet. For Linux, 3% and 9%.

This week’s activity:

• Using the data from bug 524202, Joel is tracking down exactly how and when dynamic library code is loaded. They’re past diagnostics, and are now into implementation, coaxing the linker into ordering functions in the optimal sequence. See this comment for a good summary of the issue. Joel put up a very detailed blog post about the work they’ve been doing.
• Ryan Flint updated the spellcheck bug with some new findings.
• I got a working (so far) patch for Windows cold-startup testing for Talos on bug 522807.
• Taras is in the patch review cycle for service caching in bug 516085.
• Re-enabling rebasing on Windows in bug 484799 has review now, just needs landing.
• John Dagget and Jonathan Kew have a bunch of new findings in bug 519445 for further reductions in Mac startup time spent in font system initialization. Sometimes the patch helps, sometimes it doesn’t.
• Bug 512645, removing the setTimeout 10ms wait in chrome JS has landed.
• Drew’s work on bug 506814, getting rid of Change GetPersistentDescriptor/SetPersistentDescriptor on Mac, has landed.

Projects in a holding pattern:

• Ben Hsieh has been prototyping a whole Fastload cache replacement in bug 520309.
• 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. Need to list scenarios, 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.
• No updates on Zack’s CSS parser changes in bug 513149.

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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