KCP Benchmark

如果网络从来不丢包，那么你直接用 TCP就行了，甚至直接裸UDP都没关系，但是网络因为丢包造成卡顿，特别是高峰时期丢包会上到10%的情况，移动设备上这个情况更糟糕。

我自己评测过很多，asio_kcp 的作者做过比较详细的评测，在网络变糟糕的情况下，KCP的延迟比 libenet低三倍以上：

worst network lag happen:
asio: 10:51.21
291  295   269   268   231   195   249   230   225   204

enet: 10:51.21
1563   1520    1470    1482    1438    1454    1412    1637    1588    1540

更详细的评测可以看这里：benchmark，感谢 asio_kcp 的作者 zhangyuan 详细对比了 UDT, libenet和 kcp，并给出结论如下：

• ASIO-KCP has good performance in wifi and phone network(3G, 4G).
• The kcp is the first choice for realtime pvp game.
• The lag is less than 1 second when network lag happen. 3 times better than enet when lag happen.
• The enet is a good choice if your game allow 2 second lag.
• UDT is a bad idea. It always sink into badly situation of more than serval seconds lag. And the recovery is not expected.

其他可以左右你选择的情况：

• enet has the problem of lack of doc. And it has lots of functions that you may have interest in.
• kcp's doc is in Chinese.
• Good thing is the function detail which is written in code is English. And you can use asio_kcp which is a good wrap.
• The kcp is a simple thing. You will write more code if you want more features.
• UDT has a perfect doc. UDT may have more bug than others as I feeling.

我当年主要测试了 KCP和 TCP/UDT的比较，扫了一眼 libenet觉得协议实现中规中矩，缺乏很多现代传输协议的技术，所以并没有详细测试。而 asio-kcp的作者同时给出了KCP/enet/udt三者的详细比较，为犹豫选择的人提供了更多指引。