[Truffle] while loops not being optimized? #3308

brauliobo · 2015-09-04T02:13:52Z

Under jt irb, I ran this abc method a few times:

def abc; count = 0; while(count < 100000000); count = count + 1; end; puts count; end

And it took ages to finish. Under MRI 2.2.3 it takes 2.6s.

Is there some optimization I'm missing? I have configured export JAVACMD=graalvm-jdk1.8.0/bin/java and can see this on the irb's process.

The text was updated successfully, but these errors were encountered:

eregon · 2015-09-04T10:02:47Z

If you use jt, you can pass --graal to run with graal without specifying JAVACMD yourself.

Running from a file works more reliably:

require 'benchmark'
def abc
  count = 0
  while count < 100000000
    count = count + 1
  end
  puts count
end
5.times { puts Benchmark.measure { abc } }

# run with jt ruby --graal test.rb

But there seems to currently be a bug with On-Stack-Replacement (a relatively new feature) + background compilation, which sometimes just aborts the JIT and then runs in the interpreter.

One way to currently make it work reliably in IRB is to disable background compilation:

jt ruby --graal -J-G:-TruffleBackgroundCompilation -S irb

brauliobo · 2015-09-04T11:47:46Z

@eregon I still must be doing something wrong.

First, I've recompiled jruby using the JAVACMD of graalvm, as before I did compiled with the system openjdk. Is that necessary? Anyway, it didn't made any difference.

Then I copied your code into

~/P/o/jruby git:master ❯❯❯ jt ruby --graal -J-G:-TruffleBackgroundCompilation -S irb
$ JAVACMD=/home/braulio/Projects/others/jruby/graalvm-jdk1.8.0/bin/java /home/braulio/Projects/others/jruby/bin/jruby -X+T -Xtruffle.core.load_path=truffle/src/main/ruby -J-server -J-G:-TruffleBackgroundCompilation -S irb

And the results were:

100000000
 60,640000   0,190000  60,830000 ( 59,710326)
100000000
 61,480000   0,190000  61,670000 ( 60,562418)
100000000
 61,110000   0,170000  61,280000 ( 60,200459)
100000000
 60,270000   0,210000  60,480000 ( 59,239121)
100000000
 60,690000   0,260000  60,950000 ( 59,979416)

So no real improvements yet.

eregon · 2015-09-04T14:59:38Z

@brauliobo Compilation of JRuby is fine with any javac >= 1.7, so it's not needed.

Which version of Graal did you download? 0.7?

Could you try running from a file? IRB is not an ideal environment for benchmarks.
If that is still slow, can you try with:

jt ruby --graal -J-G:+TraceTruffleCompilationDetails -J-G:-TruffleBackgroundCompilation test.rb
# or if you want for IRB:
jt ruby --graal -J-G:+TraceTruffleCompilationDetails -J-G:-TruffleBackgroundCompilation -S irb

brauliobo · 2015-09-04T15:17:27Z

@eregon graal version 0.8 (openjdk-8-graalvm-b132-linux-x86_64-0.8.tar.gz)

Runned jt ruby --graal -J-G:+TraceTruffleCompilationDetails -J-G:-TruffleBackgroundCompilation -S test.rb putting the same source on test.rb, and got the same results:

$ JAVACMD=/home/braulio/Projects/others/jruby/graalvm-jdk1.8.0/bin/java /home/braulio/Projects/others/jruby/bin/jruby -X+T -Xtruffle.core.load_path=truffle/src/main/ruby -J-server -J-G:+TraceTruffleCompilationDetails -J-G:-TruffleBackgroundCompilation -S test.rb
100000000
 60,110000   0,230000  60,340000 ( 58,566378)
100000000
 62,320000   0,080000  62,400000 ( 60,785585)
100000000
 60,400000   0,110000  60,510000 ( 59,364598)
100000000
 60,770000   0,110000  60,880000 ( 59,886292)
100000000
 62,110000   0,130000  62,240000 ( 61,201530)

eregon · 2015-09-04T15:33:52Z

@brauliobo We are using Graal 0.7 on the master branch, so you need that version instead.
I would have expected we throw an error on an incompatible Graal version but apparently it's pretty quiet in this case. We'll fix that.

Can you try with Graal 0.7?

brauliobo · 2015-09-04T16:19:25Z

ok, worked now! sorry for the misunderstading

~/P/o/jruby git:master ❯❯❯ jt ruby --graal -J-G:+TraceTruffleCompilationDetails -J-G:-TruffleBackgroundCompilation -S test.rb                                         ◼
$ JAVACMD=/home/braulio/Projects/others/jruby/graalvm-jdk1.8.0/bin/java /home/braulio/Projects/others/jruby/bin/jruby -X+T -Xtruffle.core.load_path=truffle/src/main/ruby -J-server -J-G:+TraceTruffleCompilationDetails -J-G:-TruffleBackgroundCompilation -S test.rb
[truffle] opt queued       Fixnum#<(core):core: Fixnum#< <split-7-U>                   |ASTSize       6/    6 |Calls/Thres    1000/    3 |CallsAndLoop/Thres    1000/ 1000 |Inval#              0 
[truffle] opt start        Fixnum#<(core):core: Fixnum#< <split-7-U>                   |ASTSize       6/    6 |Calls/Thres    1000/    3 |CallsAndLoop/Thres    1000/ 1000 |Inval#              0 
[truffle] opt done         Fixnum#<(core):core: Fixnum#< <opt> <split-7-U>             |ASTSize       6/    6 |Time   380( 326+54  )ms |DirectCallNodes I    0/D    0 |GraalNodes    28/   27 |CodeSize          173 |Source core: Fixnum#< 
[truffle] opt queued       Fixnum#+(core):core: Fixnum#+ <split-4-U>                   |ASTSize       7/    7 |Calls/Thres    1000/    3 |CallsAndLoop/Thres    1000/ 1000 |Inval#              0 
[truffle] opt start        Fixnum#+(core):core: Fixnum#+ <split-4-U>                   |ASTSize       7/    7 |Calls/Thres    1000/    3 |CallsAndLoop/Thres    1000/ 1000 |Inval#              0 
[truffle] opt done         Fixnum#+(core):core: Fixnum#+ <opt> <split-4-U>             |ASTSize       7/    7 |Time   370( 110+259 )ms |DirectCallNodes I    0/D    0 |GraalNodes    26/   95 |CodeSize          329 |Source core: Fixnum#+ 
[truffle] opt start        test.rb:4<OSR>                                              |ASTSize      24/   24 |Calls/Thres       0/    3 |CallsAndLoop/Thres       0/ 1000 |Inval#              0 
[truffle] opt queued       test.rb:4<OSR>                                              |ASTSize      24/   24 |Calls/Thres       0/    3 |CallsAndLoop/Thres       0/ 1000 |Inval#              0 
[truffle] opt done         test.rb:4<OSR> <opt>                                        |ASTSize      24/   37 |Time   321( 283+38  )ms |DirectCallNodes I    2/D    0 |GraalNodes    77/  116 |CodeSize          297 |Source            n/a 
100000000
  4,550000   0,050000   4,600000 (  1,506278)
100000000
  0,560000   0,000000   0,560000 (  0,271986)
100000000
  0,590000   0,000000   0,590000 (  0,266338)
100000000
  0,600000   0,000000   0,600000 (  0,278580)
100000000
  0,320000   0,000000   0,320000 (  0,292983)

eregon · 2015-09-04T16:35:15Z

Great!
No problem, we should make the Graal version requirement clearer.

chrisseaton · 2015-09-06T12:29:32Z

@brauliobo if you are experimenting with Truffle, join us in #jruby on IRC or https://gitter.im/jruby and if you are in a EU or US time zone there will normally be someone there who can help you in real time.

brauliobo · 2015-09-06T12:52:36Z

thanks @chrisseaton!

I've messaged you on #jruby channel. The gitter room is private.

I willing to fix some easy to fix failing specs on jruby+truflle.

brauliobo closed this as completed Sep 4, 2015

chrisseaton added the truffle label Sep 6, 2015

chrisseaton added this to the truffle-dev milestone Sep 6, 2015

enebo added this to the Non-Release milestone Dec 7, 2017

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[Truffle] while loops not being optimized? #3308

[Truffle] while loops not being optimized? #3308

brauliobo commented Sep 4, 2015

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brauliobo commented Sep 6, 2015

[Truffle] while loops not being optimized? #3308

[Truffle] while loops not being optimized? #3308

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brauliobo commented Sep 4, 2015

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