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> Milestones </h1>
<h1> Milestones </h1>
<ol>
<table border=1>
   <li> Rooting analysis shell green </li>
<tr>
   <li> Exactly rooted shell green </li>
  <td>1</td>
   <li> Rooting analysis browser green </li>
   <td>Rooting analysis in the shell</td>
   <li> Exactly rooted browser </li>
  <td>green on mozilla-inbound</td>
   <li> GGC no-jit shell only build on TBPL </li>
  <td>sfink</td>
   <li> GGC on AWFY </li>
  <td>2 weeks</td>
   <li> GGC faster than Ion on AWFY </li>
</tr>
</ol>
<tr>
   <td>2</td>
  <td>Exactly rooted shell</td>
  <td>green on mozilla-inbound</td>
   <td>sfink</td>
  <td>2 weeks</td>
</tr>
<tr>
  <td>3</td>
  <td>Rooting analysis in the browser browser</td>
  <td>green on mozilla-inbound</td>
  <td></td>
  <td>2 - 3 months</td>
</tr>
<tr>
  <td>4</td>
   <td>Exactly rooted browser</td>
  <td>green on mozilla-inbound</td>
   <td></td>
  <td>2 month</td>
</tr>
<tr>
  <td>5</td>
  <td>GGC no-jit shell only build on TBPL</td>
  <td>green on mozilla-inbound</td>
  <td>terrence</td>
  <td>1 month</td>
</tr>
<tr>
  <td>6</td>
  <td>JIT support</td>
   <td>Ion+GGC displayed on AWFY</td>
  <td>bhackett</td>
  <td>1 month</td>
</tr>
<tr>
  <td>7</td>
  <td>Optimized GGC in shell</td>
   <td>Ion+GGC faster than Ion-GGC on AWFY</td>
  <td>bhackett</td>
  <td>1 month</td>
</tr>
<tr>
  <td>8</td>
  <td>GGC in the browser</td>
  <td>green on AWFY</td>
  <td>terrence</td>
  <td>2 - 3 months</td>
</tr>
</table>
<h1> Steps </h1>
<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>
<h2> Exact Rooting done in JS Shell <span class="fck_mw_template"><span class="fck_mw_template">{{bug|753203}}</span></span> </h2>

Revision as of 20:25, 28 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

Milestones

1 Rooting analysis in the shell green on mozilla-inbound sfink 2 weeks
2 Exactly rooted shell green on mozilla-inbound sfink 2 weeks
3 Rooting analysis in the browser browser green on mozilla-inbound 2 - 3 months
4 Exactly rooted browser green on mozilla-inbound 2 month
5 GGC no-jit shell only build on TBPL green on mozilla-inbound terrence 1 month
6 JIT support Ion+GGC displayed on AWFY bhackett 1 month
7 Optimized GGC in shell Ion+GGC faster than Ion-GGC on AWFY bhackett 1 month
8 GGC in the browser green on AWFY terrence 2 - 3 months

Steps

Exact Rooting done in JS Shell bug 753203

12 weeks started

JIT Integration with post barriers - 4 weeks, parallelized

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

Parallelizable Sub-tasks

  • Exactly rooting the browser.
    • Milestone 1 - 4
    • evilpie, jonco, Ms2ger, sfink
    • 2 - 3 months
  • JIT integration and optimization.
    • Milestone 6 - 7
    • bhackett
    • 1 - 2 months
  • Preparing the browser to GGC.
    • No Milestone - Postbarrier verifier too slow for TBPL
    • terrence
    • 2 - 3 months
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