godsome / keffy

Introduction

Keffy is an adaptive CPU performance controller operating in the Linux kernel space as an acpi-cpufreq dynamic CPU governor. The controller autonomously adapts the rules of its operations to the currently observed CPU workload profile while keeping the workload at the desired level.

The controller has been designed as the indirect self-tuning regulator with robust recursive model estimation. For more details on the project background and the control theory applied in the controller design, see:

• Malczak, M. and Karpowicz, M.P. Fixed-point matrix inversion for linear solver in Linux kerne. in preparation, 2021.

• Getka, M., and Karpowicz, M.P. Fixed-point self-tuning CPU performance controller for Linux kernel. 2019 International Conference on High Performance Computing & Simulation (HPCS). IEEE, 2019.

• Arabas, P., and Karpowicz, M.P. Server Power Consumption: Measurements and Modeling with MSRs. Challenges in Automation, Robotics and Measurement Techniques, Springer International Publishing, 233–244, 2016

• Karpowicz, M.P. Energy‐efficient CPU frequency control for the Linux system. Concurrency and Computation: Practice and Experience 28.2 (2016): 420-437.

• Karpowicz, M.P., and Arabas, P. Preliminary results on the Linux libpcap model identification. 20th International Conference on Methods and Models in Automation and Robotics (MMAR). IEEE, 2015.

User

Installation

Select git branch based on desired kernel version.

Update grub settings to be able to select the newly installed kernel from the grub menu at boot-time. Open:

sudo vim /etc/default/grub

modify GRUB_TIMEOUT_STYLE and GRUB_TIMEOUT entry:

GRUB_TIMEOUT_STYLE="menu"
GRUB_TIMEOUT=10

and update grub:

update-grub

To download, patch, compile and install the selected kernel version with the adaptive CPU controller, run:

/bin/bash install_all.sh

Reboot. If necessary, select the new kernel. Have fun!

Demos

Kernel data plots

In order to demonstrate how the controller works, the play.sh script was created. It compiles all the necessary software and loads the module into the kernel.

Then it uses lstress program to generate the CPU load according to the following scenario:

• for the first 10 seconds, it makes the CPU use 100% of the resources
• for the following 10 seconds, it does not stress the processor at all
• for the following 20 seconds, it stresses the processor to make the CPU controller work in the controllability region

In order to start the demonstration, call:

/bin/bash play.sh

After more or less a minute, you should see plots of the processor load and frequency together with some of the parameters of the controller.

In the case of not having installed all of the required python tools, you can use install_tools.sh script:

/bin/bash install_tools.sh

Developer

When creating new branch, modify the kernel version in config.sh and update submodules. You can use checkout_repos.sh script. Bear in mind that cpufreq_adaptive submodule has different branch for every kernel version.