一个压测相关的问题

用的 siege

命令是:
siege -c 255 -t 10M 127.0.0.1:8100/buy


结果是:
Transactions: 278 hits
Availability: 21.34 %
Elapsed time: 12.89 secs
Data transferred: 0.03 MB
Response time: 5.78 secs
Transaction rate: 21.57 trans/sec
Throughput: 0.00 MB/sec
Concurrency: 124.68
Successful transactions: 0
Failed transactions: 1025
Longest transaction: 12.57
Shortest transaction: 0.00


为什么 Concurrency: 124.68
最高并发才 124,命令指定的并发是 255 啊?