Performance

Performance

Mozilla's performance program focuses on improvements to the Gecko platform and the Firefox Desktop, Firefox for Android, and Firefox OS products.

Projects

Active

Incremental Cycle Collection (ICC)

Product impact	[DESKTOP] [MOBILE] [B2G]
Goal	Implement incremental cycle collection to reduce1 cycle collector pauses in the Firefox UI. 1Reduction in cycle collector pauses will be measured with the CYCLE_COLLECTOR_FULL Telemetry probe. The degree of reduction that can be achieved is currently unclear.
Duration	TBD
Team	Andrew McCreight (lead)
Progress reports	TeamStatus: Andrew McCreight
Work	bug 850065
Dependencies
Notes

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Keep JS-accessible APIs from blocking the main thread

Product impact	[DESKTOP] [MOBILE] [B2G]
Goal	Refactor existing and provide new JS APIs to either migrate services, components, and add-ons off the main thread or at least prevent them from blocking the main thread.
Duration	TBD
Team	David Rajchenbach-Teller (lead), Paolo Amadini
Progress reports	TeamStatus: David Rajchenbach-Teller
Work	Bugzilla query
Dependencies
Notes	This project focuses on JS-accessible APIs in the context of Web Workers.

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Profiler Backend for Mobile

Product impact	[MOBILE] [B2G]
Goal	Accurate1, crash-free, deadlock-free, low overhead2 stack unwinding for the SPS profiler for Firefox for Android and Firefox OS. [1]The correct sequence of code return addresses on the stack, ideally without the unwind terminating before it gets back to main(). [2]Average unwind cost of 500 microseconds for a 30-frame backtrace on one core of a 1 GHz Cortex A9
Duration	TBD
Team	Julian Seward (lead), Benoit Girard, Mike Hommey
Progress reports	Julian Seward's blog, TeamStatus: Julian Seward, Benoit Girard, Mike Hommey
Work	bug 863453
Dependencies
Notes	May impact desktop Linux as well.

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Reducing time to first paint - Phase 1

Product impact	[DESKTOP]
Goal	A 10% reduction1 in time between XRE_Main and first paint2 during cold starts3 on Windows 7 with no extensions installed4, on reference slow hardware5, 30 seconds after an OS reboot. [1]Currently, after an OS restart, XRE_Main to firstPaint takes about 4.2 seconds on the reference hardware. A 10% reduction will be ~400ms. [2]XRE_Main as the starting point to exclude the impact of loading Firefox binaries as they grow bigger with every release. First paint to exclude the impact of Yoric's session store refactor work. [3]Cold start because a lot of the work will be focused on reducing the amount of I/O done during startup. [4]No extensions to exclude the impact of Irving's Add-on Manager work. [5]The reference hardware is a recent, slow Win7 laptop with an AMD C-50 dual-core @ 1 GHz, magnetic HDD, and 2GB shared RAM. A slow Windows laptop is used because it is consistently slow and can be easily debugged.
Duration	TBD
Team	Vladan Djeric (lead)
Progress reports	Vladan Djeric's blog, TeamStatus: Vladan Djeric
Work	bug 810156
Dependencies	Replace Add-on Manager SQLITE with JSON file project
Notes	Will measure with about:telemetry on reference hardware as aggregate Telemetry includes both warm and cold starts and a variety of hardware confirgurations.

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Replace Add-on Manager SQLITE with JSON file

Product impact	[DESKTOP] [MOBILE]
Goal	Goal: Reduce Add-on Manager impact on start-up time1 and runtime pauses2 by removing SQLITE database from XPI Provider and Add-on Repository and replacing with JSON3. 1Start-up time reduction by reducing the amount of I/O required before first paint. 2Runtime pause reduction by reducing I/O required during add-on up-to-date checks and updates, and making sure as much as possible is off main thread. 3New implementation will do no blocking I/O except minimal loading of required data during start-up.
Duration	6 weeks (approx week of May 27, 2013)
Team	Irving Reid (lead), Felipe Gomes
Progress reports	Irving Reid's blog, TeamStatus: Irving Reid, Felipe Gomes
Work	bug 853388, bug 853389
Dependencies
Notes

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Smooth Tab Animation

Product impact	[DESKTOP]
Goal	Reasonably1 smooth tabstrip animation on modern low-end AMD/Intel CPUs. The specific focus will be on use cases 1-8 defined below. New tab open of about:blank where other tabs are unaffected. (not common, this is our raw baseline) Tab close where other tabs are unaffected, and where the newly focused tab is empty. (also raw baseline) New tab open - with thumbnails preview - where other tabs are unaffected. Tab close where other tabs are unaffected, where the newly focused tab is heavy (e.g. GMail). 5-8. Same as the above, when other tabs are affected (shrunk/expanded) - up to 10 changing tabs. 1The last 70% of the animation is not lower than 50fps.
Duration	TBD
Team	Avi Halachmi (lead), Tim Taubert
Progress reports	Avi Halachmi's blog, TeamStatus: Avi Halachmi
Work	bug 815354
Dependencies	OMTC
Notes

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Network Cache Rewrite

Product impact	[DESKTOP] [MOBILE] [B2G]
Goal	A cache that causes no main thread I/O jank (directly or indirectly via locks)1, and that avoids losing the entire cache during crashes or unclean shutdown.2 [1]Currently the cache causes jank (sometimes in excess of 1 second) via main thread waiting while cache thread holds lock and does I/O. [2]Cache is currently thrown away unless clean shutdown. Cache loss rates per startup are 9% on windows desktop, 11% OSX, 22% Linux desktop, 25% metro. New design will keep all cache entries and detect corruption on a per-entry basis.
Duration	Goal is to have new code in production by end of Q4 2013
Team	Honza Bambas (lead), Michal Novotny, Jason Duell (manager)
Progress reports
Work	bug 877301
Dependencies
Notes	Cache rewrite project wiki page

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Downloads API Rewrite

Product impact	[DESKTOP]
Goal	To improve responsiveness when downloads are started, by removing the main-thread I/O caused by access to "downloads.sqlite". The concrete goal is to ensure that SQL statements involving moz_downloads no longer appear in the "slow SQL" Telemetry dashboard.
Duration	Mid August for reaching the initial goal in Nightly. Probably another month or two (with lower bandwidth) for follow-ups.
Team	Paolo Amadini (lead), Raymond Lee, Felipe Gomes, Neil Deakin
Progress reports	firefox-dev mailing list, weekly updates tool.
Work	bug 825588, Feature Page
Dependencies
Notes	The project should include a follow-up time frame to accommodate any changes identified after Firefox for Desktop has migrated to the new API, as well as handle requests to facilitate other Mozilla products and add-ons to migrate to the new API.

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Remove localStorage From Browser Pages

Product impact	[DESKTOP]
Goal	Replace about: pages use of DOM Storage with more performant storage, like indexedDB, to remove UI hangs due to main-thread IO.
Duration
Team	Marco Bonardo
Progress reports	Marco's blog, weekly updates tool.
Work	bug 729777 and dependencies
Dependencies
Notes

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Complete Asynchronous History API

Product impact	[DESKTOP]
Goal	Replace all remaining synchronous history APIs with asynchronous alternatives. This will reduce possibilities of contention between the synchronous and the asynchronous APIs, that can cause long hangs of the UI.
Duration
Team	Marco Bonardo, Asaf Romano, Raymond Lee
Progress reports	Marco's blog, weekly updates tool.
Work	bug 699850 and dependencies
Dependencies	Ensure to properly communicating add-ons compatibility issues before APIs removal, through blog post, Mozilla.dev.extensions, AMO team.
Notes	We should replace synchronous API that reports history status (bug 834541), this may be tricky since it’s required to be synchronous by some UI features and could slip off to the future, luckily it’s currently served through a cache that reduces its negative impact.

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Reduce Impact Of Bookmarks Backups On Shutdown

Product impact	[DESKTOP]
Goal	Replace synchronous main-thread bookmarks backups with asynchronous background backups. Bookmarks backups currently only run on idle, but some instances never hit idle causing the backups to occur on shutdown, which negatively impacts the shutdown time of the browser.
Duration
Team	Raymond Lee, Marco Bonardo
Progress reports	Marco's blog, weekly updates tool.
Work	bug 843357 and dependencies, https://etherpad.mozilla.org/places-backups-changes
Dependencies	Ensure to properly communicating add-ons compatibility issues before APIs removal, through blog post, Mozilla.dev.extensions, AMO team.
Notes	This project will be completed in 3 parts: Convert APIs from synchronous to asynchronous - done Various improvements to ensure we store backups only when really needed, by skipping duplicates and giving better information to the users Async conversion, although some minor parts of the code should already be async converted as we go

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Reduce Storage Connections Main-Thread Operations

Product impact	[DESKTOP] [MOBILE]
Goal	Setting up and closing a Storage database connection happens on main-thread, even if then the connection is only used through the asynchronous API. This may cause visible jank, especially when there’s other IO ongoing. Introduce a new purely asynchronous connection that never hits the main-thread and update consumers to use it. This will also ensure consumers of this connection can’t wrongly abuse of the synchronous APIs and create thread contention.
Duration
Team	David Teller, Marco Bonardo
Progress reports	Marco's blog, weekly updates tool.
Work	bug 702559, bug 874814, bug 885732 and dependencies
Dependencies
Notes	Need to blog about this change and update the documentation. The asynchronous connection landed, though it still closes the database handle on main-thread though, so fixing that is the next goal for July. Consumers conversion may take some time, Sqlite.jsm has already been converted, autocomplete is ongoing, but each consumer has very specific requirements. Goal is to complete the connection and convert most common consumers by the end of September.

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Asynchronous Places Annotations

Product impact	[DESKTOP]
Goal	Annotations allow to set specific flags on bookmarks and pages in history, to identify them or attach additional information, but they are synchronous, so bookmarks conversion to an asynchronous API is blocked on them and they are currently causing unpredictable main-thread IO. Introduce a new asynchronous API that allows to annotate pages and bookmarks asynchronously, convert internal consumers to it.
Duration
Team	Asaf Romano, Marco Bonardo
Progress reports	Marco's blog, weekly updates tool.
Work	bug 699844 and dependencies
Dependencies	Ensure to properly communicating add-ons compatibility issues before APIs removal, through blog post, Mozilla.dev.extensions, AMO team.
Notes	The old service will keep living in parallel for a while, for compatibility reasons. A first draft of the new API has been created. Asaf is going to create a first mock of the service and verify consumers requirements with it. Marco will work on the database schema and performances. Consumers conversion may take the most time and will likely be an iterative process once the API and the service are complete, by the end of the third quarter.

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Improve Text Performance

Product impact	[DESKTOP] [MOBILE] [B2G]
Goal	??
Duration
Team	John Dagget, Jonathan Kew, Simon Montagu
Progress reports
Work	bug 863248, bug 834609, bug 885689
Dependencies
Notes	Need to sync with Jet on this project definition. A first draft of the new API has been created. Asaf is going to create a first mock of the service and verify consumers requirements with it. Marco will work on the database schema and performances. Consumers conversion may take the most time and will likely be an iterative process once the API and the service are complete, by the end of the third quarter.

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Reduce impact of thumbnailing

Product impact	[DESKTOP]
Goal	Toolkit has two services that capture thumbnails of pages: a "foreground" service and a new "background" service. The foreground service draws the content windows of pages that the user has opened to canvases on the main thread. The background service exposes an API that uses a remote xul:brower to load pages on demand in the hidden window and then in the content process draws the resulting content windows to canvases. Both services write thumbnails to disk on a background thread from the main process. The goal here is to minimize the impact in the broadest sense of both services: the user's perception of jank, resource use, time taken to draw to canvas, capturing only when necessary, etc.
Duration	6 months
Team	Drew Willicox, Mark Hammond
Progress reports	Desktop weekly meeting notes, Drew's and Mark's weekly updates
Work	bug 899401
Dependencies
Notes	Ultimately we want to move all thumbnail capturing off the main thread, probably using the background service that landed in Fx 25. This service currently uses the Private Browsing feature to sandbox page loads, but declines to capture when a private browsing window is open, but can still have side-effects related to this (eg, if a capture is in-progress when PB mode is entered, it might cause cookies for a site to exist when they otherwise would not). We plan to avoid using PB mode once we have identified a technique to make these requests totally isolated.

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On Hold

Shutdown

Product impact	[DESKTOP]
Goal	Ensure 95% of Firefox desktop instances shutdown in 3 seconds or less.
Duration	TBD
Team	Benoit Girard (lead)
Progress reports	Benoit Girard's blog, TeamStatus: Benoit Girard
Work	bug 819063
Dependencies
Notes

Hold reason	Resource availability

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Improve Places Hosts Storage

Product impact	[DESKTOP]
Goal	Change the way we store hosts in Places to reduce work needed for inserting and querying pages. Currently we split www. and non www. hosts but we always use them as a single thing in all of the UI pieces, so we have to double the querying work to gather both.
Duration
Team	Marco Bonardo
Progress reports	Marco's blog, weekly updates tool.
Work	bug 843357 and dependencies
Dependencies
Notes	It's a one bug project, most of the time is needed to verify if the change may cause any issues and designing the new queries. It may take about a week.

Hold reason	Resource availability, lower priority in comparison with other perf projects

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Improve Space Efficiency Of Places URL Index

Product impact	[DESKTOP]
Goal	The current URL index in places.sqlite database takes up to 30% of the database size. The features it provides can be obtained through a smarter hashing method that should improve the space efficiency by an order of magnitude. A smaller database has positive effects on IO and fragmentation.
Duration
Team	Marco Bonardo, Taras Glek
Progress reports	Marco's blog, weekly updates tool.
Work	bug 889561
Dependencies
Notes

Hold reason	Resource availability, lower priority in comparison with other perf projects

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Proposals

Project proposals should be listed on the perf etherpad.

Archive

Completed/terminated projects are listed in the project archive.

Tools

• Telemetry
• jydoop: Efficient and Testable hadoop map-reduce in Python (Introduction from Benjamin Smedberg)
• SPS Profiler
• Buildbot/Talos

Communication

Communication Type	Mechanism	Audience
Announcements	dev-platform list	all
Meetings	First Thursday of each month, 11am PT Dial-in: Audio-only conference# 99355 People with Mozilla phones or softphones please dial x4000 Conf# 99355 US/Toll-free: +1 800 707 2533, (pin 4000) Conf# 99355 US/California/Mountain View: +1 650 903 0800, x4000 Conf# 99355 US/California/San Francisco: +1 415 762 5700, x4000 Conf# 99355 US/Oregon/Portland: +1 971 544 8000, x4000 Conf# 99355 CA/British Columbia/Vancouver: +1 778 785 1540, x4000 Conf# 99355 CA/Ontario/Toronto: +1 416 848 3114, x4000 Conf# 99355 UK/London: +44 (0)207 855 3000, x4000 Conf# 99355 FR/Paris: +33 1 84 88 37 37, x4000 Conf# 99355 Gmail Chat (requires Flash and the Google Talk plugin): paste +1 650 903 0800 into the Gmail Chat box that doesn't look like it accepts phone numbers SkypeOut is free if you use the 800 number Vidyo: Performance IRC: #perf Agenda: https://etherpad.mozilla.org/perf	all
Meeting summaries	this wiki	all
Micro status	TeamStatus	devs
Weekly status	Mozilla Status Board	devs

People

list required competencies for people and, once defined, the people working on project. note that not all of these competencies will be required for every project

Project Champion
Program Management	Lawrence Mandel
Product
Engineering	Taras Glek, Vladan Djeric

References

Related Projects

• MemShrink

Archive

Old Projects

• Mobile Startup Shrink
• Startup Performance
• Front-end Performance (i.e., responsiveness)
• Add-on Performance
• Snappy
• Mobile Performance Info

Tools

• Codesighs - a tool which analyzes code and data size.
• Performance:Tools. For measuring performance. Tip o' the propeller-cap to Daniel Roberts (zuperdee@penguinpowered.com) for the pointers.
• Performance:Probes. Project to integrate a system of performance probes into Gecko.

Documentation and Presentations

• Code Footprint Performance:Footprint_Reduction_Techniques explains common bad patterns and how to correct them.
• Performance:Profiling_JuJu. Things you should know about doing profiling. Tips and tricks for some of the tools, and lots of other Good Things To Know.
• Profiling and leak analysis on the Mac.
• Performance:Footprint_Tools. Presentation on footprint tools
• Performance:Startup slides Presentation on general performance tools
• Performance:Leak_Tools. Presentation on memory leaks detection tools
• Mac Performance Tools Presentation on performance tools that work on Mac