Add a fixed-workload harness for OptCarrot with minimal dependencies

Author: eregon

bench/optcarrot/fixed-workload.rb

@@ -0,0 +1,24 @@
+# A fixed-workload harness for OptCarrot with minimal dependencies.
+# This can be useful to debug or tune performance.
+#
+# Run with:
+# jt build --graal
+# jt ruby bench/optcarrot/fixed-workload.rb
+
+require_relative 'lib/optcarrot'
+require 'benchmark'
+
+number_of_iterations = 5000
+
+rom = File.expand_path('../examples/Lan_Master.nes', __FILE__)
+nes = Optcarrot::NES.new ['--headless', rom]
+nes.reset
+
+total = Benchmark.realtime do
+  number_of_iterations.times do
+    t = Benchmark.realtime { nes.step }
+    Truffle::Debug.print 1/t
+  end
+end
+
+Truffle::Debug.print "Total: #{total}"

doc/contributor/benchmarking.md

@@ -17,6 +17,18 @@ $ jt benchmark bench/classic/mandelbrot.rb --simple
 Output is iterations per second, printed roughly every second (more frequently
 for the first few iterations).
 
+## OptCarrot
+
+OptCarrot can be run the same way as the example above (with `bench/optcarrot/optcarrot.rb`),
+but also has a fixed-workload harness with minimal dependencies,
+which can be useful to debug or tune performance.
+
+Run the fixed-workload harness with minimal dependencies with:
+
+```bash
+$ jt ruby bench/optcarrot/fixed-workload.rb
+```
+
 # Benchmarking without the GraalVM Compiler
 
 You can turn off the GraalVM Compiler if you want, by not including it in the GraalVM build: