-n 10000 だと一瞬で終わり、正確じゃないので -n 10000000にしてみました。

48000RPS突破

KeepAliveなし デフォルト状態
Concurrency Level: 10
Time taken for tests: 500.641 seconds
Complete requests: 10000000
Failed requests: 0
Broken pipe errors: 0
Total transferred: 17080011956 bytes
HTML transferred: 14560010192 bytes
Requests per second: 19974.39 [#/sec] (mean)
Time per request: 0.50 [ms] (mean)
Time per request: 0.05 [ms] (mean, across all concurrent requests)
Transfer rate: 34116.29 [Kbytes/sec] received

KeepAliveアリ
Concurrency Level: 10
Time taken for tests: 206.268 seconds
Complete requests: 10000000
Failed requests: 0
Broken pipe errors: 0
Keep-Alive requests: 9990007
Total transferred: 17129955159 bytes
HTML transferred: 14560004368 bytes
Requests per second: 48480.62 [#/sec] (mean)
Time per request: 0.21 [ms] (mean)
Time per request: 0.02 [ms] (mean, across all concurrent requests)
Transfer rate: 83047.08 [Kbytes/sec] received