为什么Apache Benchmark的负载测试结果要好得多？

Question

我试图找到一种工具来对我的服务进行负载测试。目前，我已经使用了Apache Benchmark和Hey。

对于Apache Benchmark，命令为ab -k -c 50 -n 100 http://www.yahoo.com/，结果如下：

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0   21  21.4     39      47
Processing:    42   48   4.1     47      67
Waiting:       42   48   4.1     47      67
Total:         43   69  21.6     82     110

Percentage of the requests served within a certain time (ms)
  50%     82
  66%     87
  75%     89
  80%     91
  90%     94
  95%     97
  98%     98
  99%    110
 100%    110 (longest request)

对于Hey，命令为hey -n 100 -c 50 -q 100 http://yahoo.com ，结果如下：

Summary:
  Total:    2.5213 secs
  Slowest:  1.5375 secs
  Fastest:  0.4992 secs
  Average:  1.0112 secs
  Requests/sec: 39.6624

Latency distribution:
  10% in 0.5225 secs
  25% in 0.5645 secs
  50% in 1.3194 secs
  75% in 1.4125 secs
  90% in 1.4432 secs
  95% in 1.4590 secs
  99% in 1.5375 secs

我使用了相同数量的请求和相同大小的并发请求。唯一的区别是request per second设置为Hey。我想知道为什么Hey的结果的平均响应时间几乎比Apache Bench的结果大十倍？