Pepc stands for "Power, Energy, and Performance Configurator". This is a command-line tool for configuring various Linux and Hardware power management features.
IMPORTANT: this is tool is for debug and research purposes only. It requires root permissions, and must only be used in an isolated lab environment, not in production.
The project license is the 3-clause BSD license: https://opensource.org/licenses/BSD-3-Clause
There are many Linux tools for configuring power management in Linux, and this sub-section tries to explain why we created yet another one.
We develop, maintain, and use another project - wult, and when we measure a computer system with 'wult', we often need to configure it, for example, enable or disable various C-states, limit CPU or uncore frequency, tweak hardware features like C1 demotion, and so on.
This required us to use many different tools and sysfs interfaces. It was difficult and error-prone, until we created 'pepc', which supports everything we need for our research. For example, we can limit C-states for a specific CPU, or core, or package with just one simple command. We can enable or disable HW features without a need to remember MSR registers and bit numbers, and so on.
This project provides the tool and various modules that other projects like 'wult' can use. For example, the 'CStates' module provides methods for discovering and manipulating C-states of a Linux computer system.
- Artem Bityutskiy [email protected] - original author, project maintainer.
- Antti Laakso [email protected] - contributor, project maintainer.
Pepc supports the following features:
- C-states: discovering and configuring.
- P-states: discovering and configuring.
- CPU hotplug: onlining and offlining CPUs
- ASPM: discovering and configuring
Please, refer to the man page for details.
Some of the features are hardware-independent, but some are hardware-specific.
Before using or installing 'pepc', we recommend to install the following OS packages.
Fedora.
sudo dnf install -y rsync openssl-devel util-linux procps-ng
sudo dnf install -y python3-colorama python3-paramiko python3-argcomplete
Ubuntu.
sudo apt install -y rsync libssl-dev util-linux procps
sudo apt install -y python3 python3-colorama python3-paramiko python3-argcomplete
The easiest way of installing 'pepc' is by using the 'pip' tool, and one way of doing this is by running the following command:
pip3 install --user --upgrade git+https://github.com/intel/pepc.git@release
This command will download 'pepc' from the 'release' branch of the git repository, and install it to the home directory. Note, the "release" branch contains more stable code. To install the latest code, use the "master" branch instead.
The other way of doing this is by first cloning the git repository, checking out the 'release' branch, and running the following command:
pip3 install --user --upgrade .
You can create a standalone version of this tool by cloning the repository and running a couple of commands, here is an example:
git clone https://github.com/intel/pepc.git --branch release pepc
cd pepc
git checkout release
echo '#!/usr/bin/python3' > pepc.standalone
git archive --format zip HEAD >> pepc.standalone
chmod ug+x pepc.standalone
This will create the 'pepc.stanalone' file, which you can rename and copy to any other place, and it will work as a standalone program.
The 'pepc' tool has tab completions support, but this will only work if you have certain environment variables defined. The following command will do it:
eval "$(register-python-argcomplete pepc)"
You can put this line to your '.bashrc' file in order to have 'pepc' tab completions enabled by default.
Some 'pepc' features (e.g., '--pkg-cstate-limit') are implemented only for certain Intel platforms. This does not necessarily mean that the feature is not supported by other platforms, it only means that we verified it on a limited amount of platforms. Just to be on a safe side, we refuse changing the underlying MSR registers on platforms we did not verify.
If 'pepc' fails with a message like "this feature is not supported on this platform" for you, feel free to contact the authors with a request. Very often it ends up with just adding a CPU ID to the list of supported platforms, and may be you can do it yourself and submit a patch/pull request.