Manually running the Rubinius JIT on a totally legit fib() benchmark.

bench.rb

require 'benchmark/ips'

class Bench
  def fact(n)
    if n > 1
      n * fact(n-1)
    else
      1
    end
  end
end

b = Bench.new

Benchmark.ips do |bench|
  bench.report 'fact(2000)' do
    b.fact(2000)
  end
end

bench_jit.rb

require 'benchmark/ips'

class Bench
  def fact(n)
    if n > 1
      n * fact(n-1)
    else
      1
    end
  end
end

b = Bench.new

Rubinius::JIT.compile(b, b.method(:fact).executable)

Benchmark.ips do |bench|
  bench.report 'fact(2000)' do
    b.fact(2000)
  end
end

gistfile1.txt

$ ruby /tmp/bench.rb                                                                                                                                                                                        
Calculating -------------------------------------
          fact(2000)    38.000  i/100ms
-------------------------------------------------
          fact(2000)    801.057  (±15.0%) i/s -      3.876k

$ ruby /tmp/bench_jit.rb 
Calculating -------------------------------------
          fact(2000)    76.000  i/100ms
-------------------------------------------------
          fact(2000)    811.939  (± 3.8%) i/s -      4.104k