How to get power consumption in gem5?

[Liorkap]

Hi everyone,
When revewing the simulation results I can't find power results.
Do I need to enable it somehow?
If this is the case I would appriciate if somone can share a link to a tutorial.
Thanks in advance!

[ivanaamit]

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In gem5, power estimation isn't enabled by default in most simulation setups because it requires additional configurations and often additional tools or methodologies to measure and estimate power consumption accurately. If you're looking to include power analysis in your simulations, you'll need to configure gem5 accordingly.

Steps to Enable Power Estimation in gem5

Compile gem5 with Power Modeling Support:
Ensure that gem5 is compiled with power modeling support. This typically involves ensuring that the right flags are set in the build configuration. For example, you might need to enable specific components related to power in the scons build command.

Enable Activity Statistics:
Power modeling in gem5 relies heavily on activity statistics (like number of accesses to different cache levels, number of executed instructions, etc.). You need to make sure that these statistics are being collected during simulation. You can enable statistics collection by adding the following lines to your simulation script:

m5.stats.enable()
# Optionally, set a period to dump stats periodically
m5.stats.periodicOutput(period)

Use Power Modeling Tools:
gem5 can be integrated with external tools for detailed power and thermal analysis. Tools such as McPAT (for architectural-level power, area, and timing modeling) can be used in conjunction with gem5 to provide detailed power estimates. You will need to extract the necessary statistics from gem5 and feed them into McPAT.

Running McPAT with gem5:

• Typically, you run your simulation in gem5 and dump the statistics and configuration files.
• Use these files as input to McPAT to perform power analysis.

Setting Up the McPAT Integration:
Integration scripts and patches might be available depending on your version of gem5. These scripts facilitate the process of exporting data from gem5 and importing it into McPAT.

Example Configuration

To configure gem5 to export statistics for McPAT, you would add something like this to your simulation script:

system = System()
# Configure system components (CPUs, caches, etc.)
...

# Add a hook to dump stats at the end of simulation
atexit.register(m5.stats.dump)

# Run the simulation
m5.simulate()

Then, you would use a script to convert the output to a format compatible with McPAT and run McPAT to analyze the results.