Firefox/Projects/Startup Time Improvements

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Overview

Description: Improve startup time of Firefox and Fennec on all operating systems and platforms, including mobile devices.

Project lead: Dietrich Ayala
Project members: Ryan Flint, Drew Willcoxon, David Dahl, Vlad Vukićević, Taras Glek, Joel Reymont, Ben Hsieh, Rob Strong, Zack Weinberg

Bugs: Open | Fixed | Fixed in 3.6

Results: Performance Snapshot (snapshot numbers for last 7 days, and version comparisons)

Graphs: Windows XP | Windows Vista | Mac Leopard | Linux

Status: Weekly status updates

Active Projects

Estimated win Bug # Summary Owner Status Notes
~8% bug 525013 Investigate a more static build configuration of Firefox Joel Reymont at risk - needs review The main body of work is in the patch now, waiting on review from Ted. More details here
~10% bug 531406 Optimize code locality in binaries Taras Glek in progress See Taras' blog post for more details.
~10% bug 520309 Startup cache: replacement for fastload cache Ben Hsieh at risk - needs review Blocked on review from bsmedberg.
TBD bug 513149 Speed up CSS parsing Zack Weinberg in progress deCOM should land today (3-5% speedup for dynamic CSS updates); other changes in progress, see chart.
n/a bug 545191 Investigate Tp/Ts instability Zack Weinberg in progress Talos time variance is in some cases 10-20x larger than the change we're trying to measure
~10% bug 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.
TBD DOM flattening and XBL removal in Firefox Asaf Romano in progress TODO list the bugs involved here. See also Mobile's work in this area.
up to 25%, Mac only bug 514083 Per-file HFS+ compression on Mac OSX 10.6 Joel Reymont inactive Apple developers on the darwin list recommended pre-compressing our builds, or not compressing at all. There are issues with code-signing and the update process.


Measurement & Testing Projects

  • cold startup testing

Future Projects

Inactive Projects

  • bug 507101 - combining js components
  • minification
  • Mine the Ts DTrace viz/logs (Drew)
    • Status: complete, moved on to filesystem operations below
    • Results
      • cold startup is heavily I/O-bound. 90% of cold startup time is spent in page faults and other I/O syscalls, especially read, getattrlist, and stat.
      • majority of time spent after Firefox actually gets up and running is in XBL and CSS.
  • Log and mine filesystem operations during startup (Ryan, Drew)
  • Find dead code with JSHydra (David Dahl)
    • Status: incomplete, needs tuning and file bugs on dead code found
    • bug 506128 - run jshydra to find js functions that have no callers
  • JSHydra continuous testing
    • possible test scenarios
      • ending semicolon bug (XXX)
      • dead code finder

Completed Projects

Fixed startup bugs

References

Meta bugs

Tips, Tools

  • comparing dynamic linking time between firefox and safari on mac
    • DYLD_PRINT_STATISTICS=YES /Applications/Firefox.app/Contents/MacOS/firefox-bin
    • DYLD_PRINT_STATISTICS=YES open -a Safari

Fastload

Measuring Ts

We've been using a method Vlad blogged about here. The steps are below.

  1. save this html file somewhere locally
  2. create a new profile, run Firefox with it at least once, so all files are created, etc
  3. execute this command, with your profile name substituted, and invoking firefox in a way appropriate for your platform:

./firefox -P YourProfileName -no-remote file:///..../startup.html#`python -c 'import time; print int(time.time() * 1000);'`

The following is specific to Mac OSX and is required to evict Firefox code pages from memory and clear the Unified Buffer Cache (UBC). purge does NOT do this. 

#!/bin/sh

FF=/Volumes/Fujitsu80Gb

diskutil unmount force $FF
diskutil mount /dev/disk1s2

$FF/Minefield$*.app/Contents/MacOS/firefox-bin -no-remote -foreground -P clean file://$FF/startup.html#`python -c 'import time; print int(time.time() * 1000);'`

This assumes that your removable media is at /dev/disk1s2.

Test Coverage

This is an index of Firefox startup scenarios which need automated test coverage.

TODO:

  • groups: chrome, content, extensions, labs, other?
  • mark which need no-chrome testing
test warm start cold start notes
empty profile yes yes
everything dirty bug 515540
min places yes yes informed by places-stats, bug 515540
med places yes yes ditto
max places yes yes ditto
med session informed by test pilot data
max session ditto
downloads
url-classifier data data is fully downloaded, should test page-load for a match and no match
form history
passwords
plugins
content preferences
extensions top 5?
extension update
application update
persona applied
weave
jetpack
ubiquity
page links are visited
page has microformats
page is ssl
page has plugin
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