下面是我这边跑出的一段apache bentch日志，可看到 "Time per request"=689.946，这个值比Total max （680）还大，是否应该将 "Time per request"当然平均响应时间，还是将"Total mean"当做平均响应时间？
为什么Time per request会比Total max的值还要大？

 Concurrency Level:      1000
Time taken for tests:   0.690 seconds
Complete requests:      1000
Failed requests:        0
Write errors:           0
Total transferred:      355000 bytes
HTML transferred:       7000 bytes
Requests per second:    1449.39 [#/sec] (mean)
Time per request:       689.946 [ms] (mean)
Time per request:       0.690 [ms] (mean, across all concurrent requests)
Transfer rate:          502.47 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0   10  11.8      0      30
Processing:     7  110 186.3     19     658
Waiting:        6  110 186.4     19     658
Total:          9  120 194.1     20     680

Percentage of the requests served within a certain time (ms)
  50%     20
  66%     54
  75%    243
  80%    248
  90%    254
  95%    675
  98%    678
  99%    679
 100%    680 (longest request)