Abstract: The paper first points out the drawbacks in tradtional NPU performance evaluation methodology.The new methodology in this paper includes the impact on input data packets brought by architecture factor，which turns the uniformly distributed packet stream into nonuniformly distributed micropacket stream.Several formulars are then deduced based on this new micropacket stream.Next the paper presents a test instance in Intel IXP 2400 and makes some theoretical analysis to it.From the test we can see that the new methodology and formulars are more accurate than the old ones.

Key words: NPU, load, performance evaluation, micropacket

摘要： 指出了传统的网络处理器性能评估方法的不足。同时在其基础上考虑网络处理器体系结构对输入数据的影响，将均匀分布的报文流转化为非均匀分布的微包流，并得出了新的基于微包流的性能评估公式。同时给出了基于IXP2400的一个测试实例并对测试结果进行了理论分析。结果表明该文所提方法的评估结果更为精确。

关键词: 网络处理器, 负载, 性能评估, 微包