Clarke

Status: WIP and Experimental

Clarke tries to work out how much energy your machine is using, perhaps also how much carbon too and then ships that data off to somewhere so you can work out how to minimise it and then offset the residual.

The tool is named after Edith Clarke.

Clarke also integrates with Prometheus. Passing --listen-prometheus=<port> will start a prometheus server on port <port>.

Energy Information Sources

Calculating energy information for an arbitrary machine is challenging. Clarke currently offers three approximations:

• Based on information collected from the CPU
• Based on information collected using IPMI (for bare-metals servers)
• Based on some user-specified function over time

None are perfect and more than likely they are all going to under-approximate the amount of energy used.

The tool is also primarily focused on calculating emissions. It integrates the carbon-intensity tool to also monitor the carbon intensity of the energy in the country where the computer is located. You can provide two arguments to control this. --country takes an ISO3166 alpha-2 code for the country and --api is the path to a file containing the co2-signal API key. Note if you use GB as your code, you won't need to provide an API key.

Typical Usage

The two main parts of clarke you can change are, the "meter" (the source of wattage information) and the output (where the serialised JSON is sent). The simplest example is:

clarke monitor --meter=const:100

This will send data to stdout with a constant wattage of 100. You could equally send it over a TCP connection with:

clarke monitor --meter=const:100 --output=tcp:loopback:8080 &
nc 127.0.0.1 8080

If you redirect the output to a file called data.json you can then use the calc command to work out statistics amount energy and emission usage.

clarke calc --data=./data.json
Total time: 4h32mins                
Total energy: 0.725867kJ
Emissions: 118.000427gCO2

Variorum

For slightly more accurate information you can use the variorum backend. You must setup certain things that are hardware specific.

clarke monitor --meter=variorum

IPMI

The Intelligent Platform Management Interface (IPMI) is another way we can query information about the power usage of a computer, or usually in this case a server. Using --meter=ipmi will try to use ipmi-tool to query sensors for power consumption statistics.

Collecting Information

Clarke allows you to output the period power usage information to "flows" (like stdout, a file and a socket) and also to a capnp address. The command line tool can be used to generate an address.

clarke serve
+Server address: capnp://address

You can then point the monitor to this and it will send the information to a centralised server.

clarke monitor --machine=my-machine --period=60 -c gb --output=capnp:.capnp --reporter=log --report-period=10000