How to Use the Command 'powerstat' (with examples)

Power management and monitoring is a crucial aspect of maintaining the efficiency and longevity of computing devices. The powerstat command is a powerful tool that measures and reports the power consumption of computers, especially those with a battery power source or those supporting the Intel RAPL (Running Average Power Limit) interface. This command provides users with the capability to monitor energy usage, understand energy patterns, and derive insights for better power management.

Use case 1: Measure Power with the Default of 10 Samples with an Interval of 10 Seconds

Code:

powerstat

Motivation: Using the default settings of powerstat is an excellent way for beginners to quickly check the power consumption of their computer over a short period of time. By providing an immediate overview with minimal configuration, users can swiftly capture basic power usage data which can be insightful for initial assessments or routine checks without diving deep into configurations.

Explanation:

• The powerstat command, when run without additional parameters, defaults to taking 10 power consumption samples at 10-second intervals. This setup is suitable for quick checks and gives an overall idea of the power consumption pattern without overwhelming the user with data.

Example Output:

Running for 10 intervals of 10 seconds each.
Sample 1:  12.50 W
Sample 2:  12.45 W
Sample 3:  12.48 W
...
Average:  12.47 W

Use case 2: Measure Power with Custom Number of Samples and Interval Duration

Code:

powerstat 5 20

Motivation: Adjusting the number of samples and the interval between them allows users to tailor the power consumption measurements according to specific needs or environments. For instance, users may need to monitor power usage throughout a task of known duration, or they might want a more frequent sampling to track fluctuations more accurately due to a dynamic workload.

Explanation:

• The first argument (5) specifies the interval, which is set to 5 seconds in this example. This means the power measurement will be taken every 5 seconds.
• The second argument (20) determines the number of samples, indicating the command will take 20 measurements in total.

Example Output:

Running for 20 intervals of 5 seconds each.
Sample 1:  13.00 W
Sample 2:  13.10 W
Sample 3:  12.90 W
...
Average:  13.02 W

Use case 3: Measure Power Using Intel’s RAPL Interface

Code:

powerstat -R 5 10

Motivation: Leveraging Intel’s RAPL interface can provide more granular control and possibly more accurate power metrics for Intel-based systems. This interface allows users to get insights directly from the CPU, which is particularly useful for power users or administrators looking to optimize systems for energy efficiency or manage power budgets.

Explanation:

• The -R flag indicates that the powerstat command should utilize the RAPL interface for measurement.
• The first argument (5) sets the interval, here specified as 5 seconds.
• The second argument (10) sets the number of samples, with 10 measurements being taken.

Example Output:

Running for 10 intervals of 5 seconds each using RAPL.
Sample 1:  11.30 W
Sample 2:  11.35 W
Sample 3:  11.32 W
...
Average:  11.32 W

Use case 4: Show a Histogram of the Power Measurements

Code:

powerstat -H 2 15

Motivation: Visualizing data through histograms can be helpful for users who need to see the distribution of power consumption values at a glance. By observing this distribution, users can quickly assess variability and potential anomalies in power usage over the sampling period.

Explanation:

• The -H flag triggers the histogram display mode.
• The first argument (2) sets the interval for measurements at 2 seconds.
• The second argument (15) indicates that the command will collect 15 samples.

Example Output:

Running for 15 intervals of 2 seconds each, displaying a histogram.
11.00-11.10 W: *
11.10-11.20 W: **
11.20-11.30 W: ****
11.30-11.40 W: ***
...
Average: 11.25 W

Use case 5: Enable All Statistics Gathering Options

Code:

powerstat -a 5 20

Motivation: For detailed performance tweaking and comprehensive analysis, enabling all statistics options provides a broader spectrum of data. This is suited for users conducting in-depth studies or optimizations, where they are interested in more than just the average power consumption but other factors as well.

Explanation:

• The -a flag enables all of powerstat’s detailed statistical options.
• The first argument (5) sets the interval for metrics collection to 5 seconds.
• The second argument (20) determines that the command will take 20 samples.

Example Output:

Running with all statistics enabled for 20 intervals of 5 seconds each.
Sample 1:  12.3 W (err: ±0.5W) (min: 11.8W, max: 12.8W)
Sample 2:  12.4 W (err: ±0.6W) (min: 11.9W, max: 13.0W)
...
Average: 12.35 W

Conclusion:

The powerstat command is a versatile and essential tool for monitoring the power consumption of computing devices. Whether you are a casual user interested in understanding power usage patterns or a professional seeking to optimize energy consumption, powerstat offers a range of functionalities to meet these needs. This command’s flexibility and detailed reporting capabilities make it a valuable asset for users who wish to manage and analyze their system’s power efficiency effectively.