oprofile source output from JRuby on JVM

1_background.md

Some stuff I did to get oprofile working with JRuby:

1. Build my own oprofile according to instructions here: http://fiji.sc/Profiling_Java_Code#OProfile
2. Enable profiling, naturally
3. Run JRuby as jruby -J-agentpath:path/to/libjvmti_oprofile.so ...
4. Run commands as seen in this blog post to create annotated output, etc: https://github.com/ryoqun/rubinius/blob/4e560bf8bdc56769317aa0cc438bf5094c736d52/web/_posts/2013-03-20-profiling-jitted-ruby-code-with-oprofile.markdown

Everything worked pretty much as I expected. You might want to pass -X+C to JRuby to make sure things compile to bytecode right away (so JVM can JIT them sooner).

2_output

# This is a sample of oprofile's source output, which shows how many
# samples occurred at each line. oprofile is a native profiler, but
# there's a JVM plugin. Because JRuby eventually JITs Ruby code to
# JVM bytecode, and JVM eventually JITs that to native code, Ruby
# code can show up in oprofile results.

# The first number is sample count, and the second is percent of all
# samples at that line. This method is from the red/black benchmark.

    93  0.0070 :    while x != root && x.parent.color == Node::RED
               :      if x.parent == x.parent.parent.left
   367  0.0274 :        y = x.parent.parent.right
    59  0.0044 :        if !y.nil? && y.color == Node::RED
    74  0.0055 :          x.parent.color = Node::BLACK
    24  0.0018 :          y.color = Node::BLACK
     7 5.2e-04 :          x.parent.parent.color = Node::RED
    25  0.0019 :          x = x.parent.parent
               :        else
    12 9.0e-04 :          if x == x.parent.right
    24  0.0018 :            x = x.parent
     5 3.7e-04 :            left_rotate(x)
               :          end
     1 7.5e-05 :          x.parent.color = Node::BLACK
    18  0.0013 :          x.parent.parent.color = Node::RED
    22  0.0016 :          right_rotate(x.parent.parent)
               :        end
               :      else
    13 9.7e-04 :        y = x.parent.parent.left
   166  0.0124 :        if !y.nil? && y.color == Node::RED
   287  0.0214 :          x.parent.color = Node::BLACK
    91  0.0068 :          y.color = Node::BLACK
    62  0.0046 :          x.parent.parent.color = Node::RED
   124  0.0093 :          x = x.parent.parent
               :        else
    29  0.0022 :          if x == x.parent.left
   115  0.0086 :            x = x.parent
               :            right_rotate(x)
               :          end
     5 3.7e-04 :          x.parent.color = Node::BLACK
    99  0.0074 :          x.parent.parent.color = Node::RED
   121  0.0090 :          left_rotate(x.parent.parent)
               :        end
               :      end
               :    end