[FE training-materials-updates] Remove power management lab

Michael Opdenacker michael.opdenacker at free-electrons.com
Wed Oct 2 15:09:45 CEST 2013 

Repository : git://git.free-electrons.com/training-materials.git

On branch  : kernel-ng
Link       : http://git.free-electrons.com/training-materials/commit/?id=03da9693040dc80a5e485c5843ca1798cae448bc

>---------------------------------------------------------------

commit 03da9693040dc80a5e485c5843ca1798cae448bc
Author: Michael Opdenacker <michael.opdenacker at free-electrons.com>
Date:   Wed Oct 2 15:08:47 2013 +0200

    Remove power management lab
    
    - No longer in the agenda
    
    Signed-off-by: Michael Opdenacker <michael.opdenacker at free-electrons.com>


>---------------------------------------------------------------

03da9693040dc80a5e485c5843ca1798cae448bc
 Makefile                                           |    2 -
 .../kernel-power-management.tex                    |  130 --------------------
 .../kernel-power-management-lab.tex                |    8 --
 3 files changed, 140 deletions(-)

diff --git a/Makefile b/Makefile
index fb46e80..ac0175f 100644
--- a/Makefile
+++ b/Makefile
@@ -59,7 +59,6 @@ KERNEL_SLIDES = \
 		kernel-porting-content \
 		kernel-power-management-title \
 		kernel-power-management-content \
-		kernel-power-management-lab \
 		kernel-development-process-title \
 		sysdev-linux-intro-versioning \
 		kernel-contribution \
@@ -233,7 +232,6 @@ KERNEL_LABS   = setup \
 		kernel-locking \
 		kernel-debugging \
 		kernel-serial-driver \
-		kernel-power-management \
 		kernel-git \
 		backup
 
diff --git a/labs/kernel-power-management/kernel-power-management.tex b/labs/kernel-power-management/kernel-power-management.tex
deleted file mode 100644
index eecf374..0000000
--- a/labs/kernel-power-management/kernel-power-management.tex
+++ /dev/null
@@ -1,130 +0,0 @@
-\subchapter{Power management}{Objective: practice with standard power
-  management interfaces offered by Linux}
-
-After this lab, you will be able to:
-
-\begin{itemize}
-\item Suspend and resume your Linux system
-\item Change the CPU frequency of your system
-\end{itemize}
-
-\section{Setup}
-
-Go to the \code{$HOME/felabs/powermgt/usage/} directory.
-
-Download and extract the latest update to the Linux 3.0 kernel.
-
-Suspend/resume support for the Calao board is already included in this
-kernel.
-
-Cpu frequency scaling support for this hardware was developed by Free
-Electrons and is not yet part of the mainline kernel. Therefore,
-before compiling the 3.0 kernel, you'll have to apply the three
-patches in the \code{data/} directory of this lab:
-
-\begin{itemize}
-
-\item The first patch implements the CPU frequency driver itself,
-  which allows to change the frequency on the AT91SAM9263 CPU
-
-\item The second patch adds CPU frequency support to the serial port
-  driver. When the CPU clock is changed, the divisors for the baud
-  rate generator must be modified. This is what this patch does.
-
-\item The third patch adds CPU frequency support to the Ethernet
-  controller driver for similar reasons.
-
-\end{itemize}
-
-Configure your kernel with CPU Frequency scaling support, with the CPU
-Frequency driver for AT91, and for the different cpufreq governors.
-
-Then, compile this kernel, and boot the system over NFS on the root 
-filesystem used in the debugging lab (\code{/home/<user>/felabs/linux/debugging/nfsroot/}).
-
-\section{Suspend and resume}
-
-To suspend to RAM the Calao board, run:
-
-\begin{verbatim}
-echo mem > /sys/power/state
-\end{verbatim}
-
-The Calao board will then put itself in a low power-consumption mode,
-as the inactivity of most LEDs will show.
-
-To resume the Calao board, push the User button. After a short time,
-the board will be usable again.
-
-\section{CPU frequency control}
-
-Linux has a {\em cpufreq} driver to control CPU frequency. Of course, it can
-only switch between the limited number of operating states that your
-CPU and board can support.
-
-This interface can be controlled by userspace. This means it allows
-you to let the system user tune it from a graphical front-end, for
-example.
-
-Go to the \code{/sys/devices/system/cpu/cpu0/cpufreq/} directory, and
-see what available files are.
-
-Check what the current cpufreq governor is.
-
-Find what the allowed frequencies are on your system.
-
-Now look at the files which offer write permission. These are the ones
-you can use to control \code{cpufreq}.
-
-Switch to the \code{userspace} governor, the one that disables the
-kernel autopilot.  Now, set the frequency of \code{cpu0} to the maximum
-one. View the \code{scaling_cur_freq} file to check that the
-frequency is the one you expected.
-
-Change the governor to \code{performance}, check the current frequency,
-and change to \code{powersave} and check the frequency again.
-
-You can also select the \code{ondemand} governor, add some load to your
-target by running \code{ping -f target-ip} ({\em ping} in flood mode) from
-your PC and see the cpu frequency increase when your system gets
-pinged.
-
-Note that with the \code{userspace} governor enabled, you can implement
-your own, custom CPU frequency control based on your own criteria. You
-could check the system temperature, for example, and if it gets hotter
-than a specified threshold, you could slow down the frequency. You
-could also let a time critical process bump the frequency to the
-maximum value. You can see that in userspace, {\bf you} are the
-governor.
-
-\section{Using PowerTop}
-
-On your development PC. Install the nice PowerTop tool contributed by Intel:
-
-\begin{verbatim}
-sudo apt-get install powertop
-\end{verbatim}
-
-Run the \code{powertop} command, and see it display statistics, and
-list the top processes that cause you CPU to wake up from a deeper
-sleep state, causing it to consume more power. You could use this
-interface to find power management bugs in the applications running on
-your system.
-
-If you're using a laptop, remove the AC power for a while. This gives
-you access to live power estimates from ACPI.
-
-Also follow the tips that PowerTop gives you to conserve power, and
-try to make your system consume as little power as possible.
-
-Compare your power estimates with other people in the classroom, and
-try to achieve the best results. Any technique can be used!
-
-Thanks to Linaro, PowerTop is also available on ARM now. See
-\url{https://01.org/powertop/}.
-
-So, if your embedded architecture has CPUidle support, you could try
-this utility on it. If your embedded architecture has CPUidle support,
-even if you didn't compile powertop, you can still access idle state
-statistics by looking at the files
-in \code{/sys/devices/system/cpu/cpu<n>/cpuidle}.
diff --git a/slides/kernel-power-management-lab/kernel-power-management-lab.tex b/slides/kernel-power-management-lab/kernel-power-management-lab.tex
deleted file mode 100644
index 23a1b82..0000000
--- a/slides/kernel-power-management-lab/kernel-power-management-lab.tex
+++ /dev/null
@@ -1,8 +0,0 @@
-\setuplabframe
-{Power Management}
-{
-  \begin{itemize}
-  \item Suspend and resume your Linux system
-  \item Change the CPU frequency of your system
-  \end{itemize}
-}

More information about the training-materials-updates mailing list