benchmark/README.md: [ci skip] write documentation

about this directory

benchmark/driver.rb: ditto

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63903 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

benchmark/README.md

@@ -0,0 +1,49 @@
+# ruby/benchmark
+
+This directory has benchmark definitions to be run with
+[benchmark\_driver.gem](https://github.com/benchmark-driver/benchmark-driver).
+
+## Normal usage
+
+Execute `gem install benchmark-driver` and run a command like:
+
+```console
+# Run a benchmark script with the ruby in the $PATH
+benchmark-driver benchmark/erb_render.yml
+
+# Run all benchmark scripts with multiple Ruby executables or options
+benchmark-driver benchmark/*.yml -e /path/to/ruby -e '/path/to/ruby,--jit'
+
+# Or compare Ruby versions managed by rbenv
+benchmark-driver benchmark/*.yml --rbenv '2.5.1;2.6.0-preview2,--jit'
+```
+
+## make benchmark
+
+Using `make benchmark`, `make update-benchmark-driver` automatically downloads
+the supported version of benchmark-driver, and it runs benchmarks with the downloaded
+benchmark-driver.
+
+```console
+# Run all benchmarks with the ruby in the $PATH and the built ruby
+make benchmark
+
+# Or compare with specific ruby binary
+make benchmark COMPARE_RUBY="/path/to/ruby --jit"
+
+# You can specify any option via $OPTS
+make benchmark OPTS="--help"
+```
+
+## make benchmark-each
+
+`make benchmark-each` is similar to `make benchmark`, but it allows to execute
+some specific benchmarks.
+
+```console
+# Run vm1 benchmarks
+make benchmark-each ITEM=vm1
+
+# Match erb but exclude app_erb to run only erb_render
+make benchmark-each ITEM=erb OPTS="--exclude=app_erb"
+```

benchmark/driver.rb

@@ -1,6 +1,6 @@
 #!/usr/bin/env ruby
 #
-# Ruby Benchmark driver
+# Wrapper of benchmark-driver command for `make benchmark` and `make benchmark-each`.
 #
 
 begin