Javascript:SpiderMonkey:ProjectGenerationGarbageCollection: Difference between revisions
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<b>Tracking Bug:</b> [meta] Implement generational garbage collection - <span class="fck_mw_template"><span class="fck_mw_template"><span class="fck_mw_template">{{bug|619558}}</span></span></span> | <b>Tracking Bug:</b> [meta] Implement generational garbage collection - <span class="fck_mw_template"><span class="fck_mw_template"><span class="fck_mw_template">{{bug|619558}}</span></span></span> | ||
< | <h1> Steps </h1> | ||
< | <h2> Exact Rooting done in JS Shell <span class="fck_mw_template"><span class="fck_mw_template">{{bug|753203}}</span></span> </h2> | ||
<p>12 weeks started | <p>12 weeks started | ||
</p> | </p> | ||
| Line 40: | Line 40: | ||
</li></ul> | </li></ul> | ||
</li></ul> | </li></ul> | ||
< | <h2> JIT Integration with post barriers - 4 weeks, parallelized </h2> | ||
<ul><li> IonMonkey <span class="fck_mw_template"><span class="fck_mw_template">{{bug|831506}}</span></span> - 1 week (bhackett) | <ul><li> IonMonkey <span class="fck_mw_template"><span class="fck_mw_template">{{bug|831506}}</span></span> - 1 week (bhackett) | ||
</li><li> JaegerMonkey <span class="fck_mw_template"><span class="fck_mw_template">{{bug|764876}}</span></span> - 2 days (bhackett) | </li><li> JaegerMonkey <span class="fck_mw_template"><span class="fck_mw_template">{{bug|764876}}</span></span> - 2 days (bhackett) | ||
</li><li> Baseline JIT <span class="fck_mw_template"><span class="fck_mw_template">{{bug|831507}}</span></span> - <ask jandem/djvj for an estimate> | </li><li> Baseline JIT <span class="fck_mw_template"><span class="fck_mw_template">{{bug|831507}}</span></span> - <ask jandem/djvj for an estimate> | ||
</li></ul> | </li></ul> | ||
< | <h2> Generational Garbage Collection in the Shell </h2> | ||
<ul><li> Implement prototype algorithm (terrence) - 1 week | <ul><li> Implement prototype algorithm (terrence) - 1 week | ||
</li><li> This is a potential milestone: we would need to build it and test it on TBPL similar to how |r| works now -- |GGCJS|. | </li><li> This is a potential milestone: we would need to build it and test it on TBPL similar to how |r| works now -- |GGCJS|. | ||
| Line 53: | Line 53: | ||
</li></ul> | </li></ul> | ||
</li></ul> | </li></ul> | ||
< | <h2> Exactly Root the Browser <span class="fck_mw_template"><span class="fck_mw_template">{{bug|831379}}</span></span> - 10 weeks </h2> | ||
<ul><li> This is a potential milestone: we would turn on exact rooting for release FF at this point. We would not get a performance boost from this (necessarily), but it would lock in our work to this point. | <ul><li> This is a potential milestone: we would turn on exact rooting for release FF at this point. We would not get a performance boost from this (necessarily), but it would lock in our work to this point. | ||
</li></ul> | </li></ul> | ||
< | <h2> Performance Tuning - 4 weeks (This should probably start asap) </h2> | ||
<ul><li> Implement a Nursery <span class="fck_mw_template"><span class="fck_mw_template">{{bug|706885}}</span></span> - 1 week | <ul><li> Implement a Nursery <span class="fck_mw_template"><span class="fck_mw_template">{{bug|706885}}</span></span> - 1 week | ||
</li><li> Test against V8 Earley-Boyer benchmark. | </li><li> Test against V8 Earley-Boyer benchmark. | ||
| Line 64: | Line 64: | ||
</li><li> Refactor code to avoid rooting on hot paths and keep rooter overhead acceptable <span class="fck_mw_template"><span class="fck_mw_template">{{bug|831886}}</span></span> (bhackett) - done | </li><li> Refactor code to avoid rooting on hot paths and keep rooter overhead acceptable <span class="fck_mw_template"><span class="fck_mw_template">{{bug|831886}}</span></span> (bhackett) - done | ||
</li></ul> | </li></ul> | ||
< | <h2> Make the Post Barrier Verifier Green in the browser <span class="fck_mw_template"><span class="fck_mw_template">{{bug|764882}}</span></span> </h2> | ||
<ul><li> Investigate how long it will take to do generational barriers - 1 week | <ul><li> Investigate how long it will take to do generational barriers - 1 week | ||
</li><li> We may need to rewrite the maps in xpconnect and the browser in terms of HashTable: this could be a bunch of work. | </li><li> We may need to rewrite the maps in xpconnect and the browser in terms of HashTable: this could be a bunch of work. | ||
</li><li> Make JS_IsAboutToBeFinalized indirect <span class="fck_mw_template"><span class="fck_mw_template">{{bug|765432}}</span></span> - 10 weeks | </li><li> Make JS_IsAboutToBeFinalized indirect <span class="fck_mw_template"><span class="fck_mw_template">{{bug|765432}}</span></span> - 10 weeks | ||
</li></ul> | </li></ul> | ||
< | <h1> Other </h1> | ||
<ul><li> Should we establish a new benchmark specifically for GGC. (sfink votes yes) | <ul><li> Should we establish a new benchmark specifically for GGC. (sfink votes yes) | ||
<ul><li> What would it measure? there are multiple goals, e.g. throughput/MMU/pause time | <ul><li> What would it measure? there are multiple goals, e.g. throughput/MMU/pause time | ||
| Line 86: | Line 86: | ||
</li></ul> | </li></ul> | ||
</li></ul> | </li></ul> | ||
< | <h1> Risks </h1> | ||
<ul><li> Team is responsible for many top crashers | <ul> | ||
</li | <li> Team is responsible for many top crashers</li> | ||
<li> External rooting API has not been designed</li> | |||
</li | <li> GGC algorithm has not been decided on - it may not be faster</li> | ||
<li> JSD1 exact rooting is lurking</li> | |||
</li | </ul> | ||
</li></ul | |||
Revision as of 19:16, 16 February 2013
Wiki conversion of original Google Document: https://docs.google.com/a/jamsni.com/document/d/1-GZ8F0ZabvdpCnRQaecId0yuu4QFYr5pAvnRC_KFchc/edit
Objective
Implement Generational Garbage collection in Spider Monkey. <Some goal based off V8 performance delta % on Earley Boyer benchmark>
Accountable: Naveed
Responsible: Terrence, Steve, Jon, Nicholas, evilpie and Ms2ger
Consulted: bhackett billm
Informed: Product Marketing
Tracking Bug: [meta] Implement generational garbage collection - bug 619558
Steps
Exact Rooting done in JS Shell bug 753203
12 weeks started
- Rooting Analysis on TinderBox (sfink) - done
- Still need to unhide it for inbound - get it green, keep it green
- Get the root analysis build green - two weeks?
- Get jit-tests green bug 745742
- Get js ref tests green
- Get jsapi-tests green bug 831376
- Rooting analysis fuzz bugs bug 773746
- Rely on static analysis to make this not be a whack-a-mole game
- Remove E4X - done
- Do something about JSD
- Add exact roots to stack structures - 2 weeks
- AddRoot/RemoveRoot for Heap structures - 4 weeks
- Static code analysis bug 831409
- Fix all discovered rooting hazards (~800) (sfink,jonco) - 4 weeks
- Optimize all discovered over-rooting (~100)
- Automate static analysis bug 834912 (sfink)
JIT Integration with post barriers - 4 weeks, parallelized
- IonMonkey bug 831506 - 1 week (bhackett)
- JaegerMonkey bug 764876 - 2 days (bhackett)
- Baseline JIT bug 831507 - <ask jandem/djvj for an estimate>
Generational Garbage Collection in the Shell
- Implement prototype algorithm (terrence) - 1 week
- This is a potential milestone: we would need to build it and test it on TBPL similar to how |r| works now -- |GGCJS|.
- Re-implement HashTable rekeying
- We undid this code because it was a perf regression and was still a bit buggy. (terrence) - 3 weeks
- at least part of this is bug 726687
Exactly Root the Browser bug 831379 - 10 weeks
- This is a potential milestone: we would turn on exact rooting for release FF at this point. We would not get a performance boost from this (necessarily), but it would lock in our work to this point.
Performance Tuning - 4 weeks (This should probably start asap)
- Implement a Nursery bug 706885 - 1 week
- Test against V8 Earley-Boyer benchmark.
- Also v8 deltablue, raytrace
- We may need to Implement Bill’s Pools/Zones idea to get the nursery to the requisite perf bug 759585 - 6 weeks
- Refactor code to avoid rooting on hot paths and keep rooter overhead acceptable bug 831886 (bhackett) - done
Make the Post Barrier Verifier Green in the browser bug 764882
- Investigate how long it will take to do generational barriers - 1 week
- We may need to rewrite the maps in xpconnect and the browser in terms of HashTable: this could be a bunch of work.
- Make JS_IsAboutToBeFinalized indirect bug 765432 - 10 weeks
Other
- Should we establish a new benchmark specifically for GGC. (sfink votes yes)
- What would it measure? there are multiple goals, e.g. throughput/MMU/pause time
- Should we make it a public benchmark?
- What workloads should we consider?
- compartmental GC very important to us, not necessarily applicable to other implementations
- allocation rate (broken down into live vs garbage), steady behavior vs swapping between allocation + computation modes, etc.
- How can we keep our advantage on Splay benchmark
- possible to do with TI --- look at types of objects promoted from nursery to major heap, eventually start allocating them directly in the major heap
- Compacting GC - Revisit in Febuary/March - 1 Month
- Delayed until exact rooting is fully done. We can add this in if we have time in the schedule that we cannot parallelize.
Risks
- Team is responsible for many top crashers
- External rooting API has not been designed
- GGC algorithm has not been decided on - it may not be faster
- JSD1 exact rooting is lurking