EMT 介绍
EMT 是一个脚本工具，用来收集和存储性能相关的度量数据，例如 cpu 使用率、内存使用率、IO等。EMT exists to bridge a
gap between system and application-specific performance metrics gathering. It
provides an easy way to gather common system performance metrics, as well as
providing a simple plugin-based interface to collect custom application-
specific metrics.