bench: add child process read perf benchmark

benchmark/misc/child-process-read.js

@@ -0,0 +1,28 @@
+var common = require('../common.js');
+var bench = common.createBenchmark(main, {
+  len: [64, 256, 1024, 4096, 32768],
+  dur: [5]
+});
+
+var spawn = require('child_process').spawn;
+function main(conf) {
+  bench.start();
+
+  var dur = +conf.dur;
+  var len = +conf.len;
+
+  var msg = '"' + Array(len).join('.') + '"';
+  var options = { 'stdio': ['ignore', 'ipc', 'ignore'] };
+  var child = spawn('yes', [msg], options);
+
+  var bytes = 0;
+  child.on('message', function(msg) {
+    bytes += msg.length;
+  });
+
+  setTimeout(function() {
+    child.kill();
+    var gbits = (bytes * 8) / (1024 * 1024 * 1024);
+    bench.end(gbits);
+  }, dur * 1000);
+}