Getting Started with Energy Analysis

Use energy analysis to investigate power consumption and identify system behaviors that waste energy on a Linux*, Windows*, or Android* system running on Intel® architecture. Energy analysis includes collecting power-relevant metrics and examining the results to determine if the target system is behaving as expected regarding its energy use.

Analysis generally starts with a summary report of data collected on the target system to see if the system is using energy-efficient, low power states. If results fail to meet expectations, additional examination of the data on a timeline and correlating metrics to determine a cause may be required.

There are three typical workflows for power analysis:

Workflow

Benefit

Run a collection directly on a Windows, Android, or Linux OS target system using the Intel SoC Watch command line tool and view a text (CSV-formatted) summary report.

The report can be viewed immediately on the target system and additional collections can be run based on what is learned. No time is spent copying result files to a host until you want a more detailed look at data over time.

Run a remote collection on a Linux or Android OS target system from a Windows or Linux host system using the energy analysis project type available with Intel System Studio.

No need to learn command line syntax. Launch and view results using a graphical user interface that includes timeline visualization of results. The tool brings the results back to the host for you so that you can see a summary and dive into timeline results seamlessly.

Run a collection directly on a Windows, Android, or Linux OS system using the Intel SoC Watch command line tool and import the results to Intel VTune™ Amplifier for visualization.

For those familiar with the powerful graphical user interface of Intel VTune Amplifier, this option provides the familiar zoom and filter capabilities for examining the data over time and correlate across all metrics. Use the Intel SoC Watch command line to collect data and generate a VTune Amplifier export file, then copy that file to the host system and import into VTune Amplifier.

The steps below detail the first workflow and collect the most common energy consumption metrics.

Step 1: Configure and Install on Target System

Start with the Installation section of the Intel SoC Watch Release Notes for your target system's operating system to find detailed instructions for installing the Intel SoC Watch command line tool and, if needed, configuring your environment. Release Notes can be found on the host system in the targets directory after installing Intel System Studio or on the target system in the product's documentation directory after extracting the Intel SoC Watch package. The latest Intel SoC Watch documents are available online at the Intel Developer Zone site and are linked below.

Step 2: Collect Data

  1. Open a command prompt with administrative/root privileges on the target system where Intel SoC Watch was installed.

  2. Enter the command below to capture CPU time in low power states over a 60-second period.

    socwatch -t 60 -f cpu-cstate -m -o results/test

Step 3: View Results

When collection completes, a message appears with the location of the result files. In this example, the summary report is located in the current directory in the results/test.csv file.

  1. Open the test.csv file using a spreadsheet viewer (such as Microsoft Excel*) or a text viewer (such as vi/vim or Microsoft Wordpad*).

    Note

    Some text viewers give better column alignment than others.

  2. Review the tables in the report file. A partial set of tables is shown in the example report below.

Example report:

Example report interpretation: When reading C-State tables, a higher C-State number means lower power consumption. C0 indicates high energy consumption and C7 or C10 is the lowest energy consumption. Looking at the table in the example report, the system spent 93.65% of the collection time in the package-level C2 state while the cores were in C7, their lowest state. An area for further exploration would be what prevented the package from going into its lowest energy state.

Next Steps

After running a basic collection on a target system, consider one of the following next steps:

  • Learn about the additional data that can be collected on the target system by entering the help command: socwatch -h. The Intel SoC Watch User's Guide (linked below) has a list of all metrics the tool provides, some of which may not be supported on your particular platform.

  • Define a scenario you want to analyze for energy use. For example:

    • System idle scenario, where the system is not in use during the collection time and is expected to drop its energy use to the lowest possible. Use a longer collection period (several minutes) to give the system time to transition to deep sleep or hibernation.

    • Active workload, such as video or audio playback. Start both an activity and collection for a predetermined time or let the collection run until manually stopped. Use the help command to learn about Intel SoC Watch options that allow launching a workload, delaying a collection start, and running for indefinite time.

  • Generate a trace file (*.pwr) that can be imported and viewed in Intel® VTune™ Amplifier by adding the -r vtune option to the command line. For more information, see https://software.intel.com/en-us/socwatch-help-intel-energy-analysis.

  • Create an energy analysis project in Intel System Studio and run a collection on a Linux target system. For more information, see https://software.intel.com/en-us/socwatch-help-running-energy-analysis-using-intel-system-studio.

Documentation and Resources

Document

Description

User's Guide: Android and Linux | Windows

The Intel SoC Watch User's Guide is a reference manual with explanations of all command line options and features as well as example reports.

The guide is available in the product's documentation directory after installation. A copy is also available from the Intel Developer Zone website.

Release Notes: Android | Linux | Windows

The Intel SoC Watch Release Notes contain the most up-to-date information about the product, including a product description, technical support, and known limitations and issues for a particular operating system. This document also contains system requirements for installing the product.

The guide is available in the product's documentation directory after installation. A copy is also available from the Intel Developer Zone website.

Online Help

The energy analysis help provides basic information about running a collection. It also includes information about how to view and analyze the results in Intel System Studio or Intel VTune Amplifier.

Command line help

You can access general help for the Intel SoC Watch command line interface by entering the following command:

socwatch -h

Legal Information

Intel, Intel VTune Amplifier, and the Intel logo are trademarks of Intel Corporation in the U.S. and/or other countries.

*Other names and brands may be claimed as the property of others.

Microsoft, Windows, and the Windows logo are trademarks, or registered trademarks of Microsoft Corporation in the United States and/or other countries.

Copyright 2017-2018 Intel Corporation.

This software and the related documents are Intel copyrighted materials, and your use of them is governed by the express license under which they were provided to you (License). Unless the License provides otherwise, you may not use, modify, copy, publish, distribute, disclose or transmit this software or the related documents without Intel's prior written permission.

This software and the related documents are provided as is, with no express or implied warranties, other than those that are expressly stated in the License.

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