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Powerstat measures and reports your computer's power consumption in real time. On mobile PCs, it uses ACPI battery information to measure the power drain of the entire system.

Powerstat can also report RAPL power domain measurements. These are available only on some hardware such as Intel Sandybridge and newer, and cover only part of the machine's components such as CPU, DRAM, and graphics. However, they provide accurate and immediate readings and don't require a battery at all.

The output is like vmstat but also shows power consumption statistics: at the end of a run, powerstat will calculate the average, standard deviation, and minimum and maximum values. It can show a nice histogram too.