有些服务器出厂设置开启了CPU节能特性，该功能节省电量但CPU的运算性能也会下降，如何查询当前主机是否开启节能开关呢？
# more /proc/cpuinfo | grep epb | wc -l
epb为节能开关的指令集，如果结果大于0表示当前CPU工作在节能模式。
epb节能开关可通过bios设置。
关于EPB的介绍：
The last big bang is power management, something Intel calls Energy Performance Bias(EPB). EPB is not just frequency and voltage scaling like all modern CPUs have, it is extremely sophisticated and allows you to have multiple profiles for a CPU, power savings, performance, and 14 other settings between those two extremes. You can tune it for your workload in ways that were not possible in the past.