http://qiita.com/flexfirm/items/ac5a2f53cfa933a37192

$ ab -n 100 -c 100 http://www.example.co.jp/

$ ab -n 100 -c 20 http://fl8.jp/
This is ApacheBench, Version 2.3 <$Revision: 655654 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking fl8.jp (be patient).....done


Server Software:        Apache/2.2.15
Server Hostname:        fl8.jp
Server Port:            80

Document Path:          /
Document Length:        25 bytes

Concurrency Level:      20
Time taken for tests:   1.027 seconds
Complete requests:      100
Failed requests:        68
   (Connect: 0, Receive: 0, Length: 68, Exceptions: 0)
Write errors:           0
Non-2xx responses:      68
Total transferred:      63053 bytes
HTML transferred:       41965 bytes
Requests per second:    97.33 [#/sec] (mean)
Time per request:       205.482 [ms] (mean)
Time per request:       10.274 [ms] (mean, across all concurrent requests)
Transfer rate:          59.93 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        8    8   0.1      8       8
Processing:    17  177 206.1     48     586
Waiting:       17  160 180.7     47     508
Total:         25  185 206.1     56     594

Percentage of the requests served within a certain time (ms)
  50%     56
  66%     86
  75%    432
  80%    451
  90%    520
  95%    541
  98%    585
  99%    594
 100%    594 (longest request)

Time taken for tests:   1.027 seconds
Requests per second:    97.33 [#/sec] (mean)
Total:         25  185 206.1     56     594