apache ab压力测试问题

[yxb0317]

ab -n 5000 -c 100 http://localhost:8080/MyAbTest/test
This is ApacheBench, Version 2.3 <$Revision: 1528965 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking 58.67.199.171 (be patient)
Completed 500 requests
Completed 1000 requests
Completed 1500 requests
Completed 2000 requests
Completed 2500 requests
Completed 3000 requests
Completed 3500 requests
Completed 4000 requests
Completed 4500 requests
Completed 5000 requests
Finished 5000 requests


Server Software: nginx/1.8.0
Server Hostname: 58.67.199.171
Server Port: 86

Document Path: /test
Document Length: 2118 bytes

Concurrency Level: 100
Time taken for tests: 31.760 seconds
Complete requests: 5000
Failed requests: 0
Total transferred: 11300000 bytes
HTML transferred: 10590000 bytes
Requests per second: 157.43 [#/sec] (mean)
Time per request: 635.207 [ms] (mean)
Time per request: 6.352 [ms] (mean, across all concurrent requests)
Transfer rate: 347.45 [Kbytes/sec] received

Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 1 0.1 1 2
Processing: 195 632 155.5 620 1483
Waiting: 195 632 155.5 620 1483
Total: 196 632 155.6 620 1484

Percentage of the requests served within a certain time (ms)
50% 620
66% 677
75% 714
80% 743
90% 842
95% 921
98% 998
99% 1070
100% 1484 (longest request)

上面是测试结果,我想问一下Time per request: 6.352 [ms] (mean, across all concurrent requests)这个指标说明了平均每次请求花费6.352毫秒,但是Percentage of the requests served within a certain time (ms)中,都是620毫秒,这两个指标的意思不一样的吗,测试结果应该怎么分析的啊,第一次做压力测试,求大神指点指点,谢谢啦