July 22nd 2008

Attendees

• intel: moh, carmen, shengnan, jungwoo
• mozilla: joel, dave, andreas
• adobe: mason, dan, edwin s, rob, steve, vlad, jennifer, rick

Updates

• (Andreas) SSE2 calling conventions. SSE2-only JIT? Shall we specialize with SSE2-only?
  • This may make slower processers even slower. This would affect Flash. This should be investigated though. Would compile-time be enough? Need to look into this. SSE2 or later machines would makes sense.
  • bug 440601
    • gregor at UCI posted some python code to look at functions on mac -- might need volunteers to help with win and mac implementations
    • would anyone be willing to buddy up with andreas for win and linux?
      • edwin suggests andreas do a little profiling on some built-ins to see if performance is improved first.
      • performance-critical stuff seems to be in lib.c -- include them directly? seems to sound okay!

• (andreas/gregor) Register usage analysis for builtins
  • andreas will try to provide some numbers for the next call

• (edwin) vprop for GCC
  • working on some patches for this
    • will push patches, pending successful testing on windows

• (edwin) fragmento
  • assembler is long-lived but we want it to be short-lived
  • not re-using exit pages was using a lot of memory.
    • now, when recompiling a tree, optimizations make cache usage about 75% faster
  • andreas asks: will implemental growth patch still be needed?
    • mason did the testing on bug 443111 -- some tests fail on linux, but other platforms look fine.
    • edwin will look into these crashes.
    • andreas will wait to make his check-in until edwin has investigated a bit further.
  • edwin also did a lot of code clean-up with this patch.
  • what about getting rid of the exit block entirely? (rick)
    • this would be nice, but haven't thought about the details yet.
  • in the end, edwin thinks we will want to use shared side exists.
    • andreas has not tried this yet.

• (moh) Speeding up the hot loop of MMGc PinStackObjects using SSE2 parallel compares
  • https://bugzilla.mozilla.org/show_bug.cgi?id=446556
    • a large amount of stack scanning is happening.
    • moh has gotten about 7% performance improvements so far
    • there is a similar loop in MarkItem, but adjusting that has not yielded as much improvement.
    • edwin thinks this is a valuable patch

• (Jungwoo) Update on parallel JIT'ing in TT.
  • Is trying moving all patches to interpreter side.
  • 15-30% speedups could be possible!
    • edwin would like numbers with and without trees (these are without trees)
    • did intel look into MD5? no, not yet,

• (Steven) Is tracking down performance issues for a Flex-based app for Tamarin Tracing. New issues are coming up with TT vs. TC issues in doing this.
  • working on improving superwords -- preliminary patch is posted for review
    • roughly 20% interpretor speed-up, but no tracing improvement
    • trying to identify some other areas to work on

• (Edwin) tri-server
  • shared sandbox is online! everyone is welcome to use this now.
  • working on modifying build system to pull patches from different users' repositories for they get queued up properly.

• (dan) automated performance metrics
  • we have now published a performance page.
    • once a checkin is made, buildbot runs performance tests on various platforms and posts results.
    • weekly performance data is also summarized.
  • how to track feedback to this system? log in bugzilla.

• (dave) TraceMonkey:
  • still working on additional patches
    • will write up a wiki article soon
  • basic ARM testing is underway

• (Mingqui) Submitted 2 patches a few weeks ago. Steven at Adobe still needs to review these…
  • https://bugzilla.mozilla.org/show_bug.cgi?id=438889
  • https://bugzilla.mozilla.org/show_bug.cgi?id=438881