Benchmark script: improve file naming, readme consistency

The example arguments file is named with _example suffix like the existing example method list,
and the branch and develop CSV files are so named and listed in (x, y) order everywhere.

Author: smowton

scripts/benchmark/README.md

@@ -14,7 +14,7 @@ Assuming there is a java maven module installed in `project-name/module-core/`,
 and the `jbmc` main directory is in `/path/to/jbmc`, go to
 `project-name/module-core/target/classes`, and run:
 
-    /path/to/scripts/benchmark/benchmark_java_project.js /path/to/jbmc -l method_list_example.txt -a java_arguments.json -m path/to/jbmc/lib/java-models-library/target/core-models.jar | tee result.json
+    /path/to/scripts/benchmark/benchmark_java_project.js /path/to/jbmc -l method_list_example.txt -a jbmc_arguments_example.json -m path/to/jbmc/lib/java-models-library/target/core-models.jar | tee result.json
 
 This will display the results and save them into the file `result.json`.
 
@@ -29,9 +29,9 @@ This will create a `result.csv` file containing the results.
 # Comparing two runs
 
 Assuming the results have been converted to csv and saved into two files named
-benchmark1.csv and benchmark2.csv:
+develop.csv and branch.csv:
 
      gnuplot draw_scatter.gp
 
-will create a png file `perf_out.png` with the time from the first run on the
-`y` axis and the second on the `x` axis.
+will create a png file `perf_out.png` with the time from the branch / changed run on the
+`y` axis and the develop / original run on the `x` axis.

scripts/benchmark/draw_scatter.gp

@@ -7,8 +7,8 @@ set xrange [30:60000]
 set yrange [30:60000]
 set logscale x 10
 set logscale y 10
-set ylabel 'time (sec.) on branch'
 set xlabel 'time (sec.) on develop'
+set ylabel 'time (sec.) on branch'
 
-plot '< join benchmark1.csv benchmark2.csv' using 6:3 with points, \
+plot '< join develop.csv branch.csv' using 3:6 with points, \
   x with lines