Firefox Startup Performance Weekly Summary
Apologies for not posting last week, but I was on vacation. Recent activity:
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I've updated the project wiki page with a table of summarized numbers for at-a-glance tracking of progress. I need to disable superfetch and try again on Windows.
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Our measurements of cold startup showed a huge regression on Windows from 3.5 to 3.6. Tracking this in bug 517741.
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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.
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JAR Performance: I'm going to test-land bug 510844 on the Places branch to figure out what's going wrong on the tinderbox. It should increase throughput of JAR file reading, possibly affecting Ts and Tp.
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Removing the needless stats of already-fastloaded components is being looked at more broadly in bug 511761 by Ben Hsieh with help from Taras and others. There are a bunch of dirty ways to trigger component re-registration and fastload cache invalidation, so I filed bug 517515 to consolidate these in an explicit manner.
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Cold Startup Testing: Drew and Alice made a bunch of progress on bug 510587, to create a new Ts that measures cold startup. Alice is working on mobile Talos though, so this is sidelined for a bit. The only issue left is reliable Windows measurement, but we're not going to block on it, can live with Mac and Linux to start off.
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Preference Files: Taras Glek has been working on combining the different preference files into a single one at build time, in bug 507288. The patch is there, and is just trying to find a way to land cleanly.
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Service Caching: Vlad, Drew and Taras are working on caching some services globally for C++ code. For example, 50% of the GetService calls for the IO service originate from NS_NewURI usage. This work is in bug 516085. Projects in a holding pattern:
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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.
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PGO for Places, mozStorage and SQLite: Still blocking on Rel-Eng fixing bug 486783, which now has patches!
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Static Analysis: No progress on bug 506128. David needs to file a bug with the final log of named-yet-uncalled functions.
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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.
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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.
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Ryan Flint blogged about various front-end improvements he's working on that affect startup time.
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CSS Parsing Time: Zack says his work in bug 513149 might improve CSS parsing time by 50%, and it's next on his list.