[bootlin/training-materials updates] master: Real-time lab: use chrt before adding load (79e0c827)
Thomas Petazzoni
thomas.petazzoni at bootlin.com
Fri Oct 29 10:46:38 CEST 2021
Repository : https://github.com/bootlin/training-materials
On branch : master
Link : https://github.com/bootlin/training-materials/commit/79e0c8277c5a96519744e24fd1dbed2fccc432a2
>---------------------------------------------------------------
commit 79e0c8277c5a96519744e24fd1dbed2fccc432a2
Author: Michael Opdenacker <michael.opdenacker at bootlin.com>
Date: Thu May 20 18:32:11 2021 +0200
Real-time lab: use chrt before adding load
- Making more sense in my opinion, running the test
program without chrt just gives meaningless results.
Signed-off-by: Michael Opdenacker <michael.opdenacker at bootlin.com>
>---------------------------------------------------------------
79e0c8277c5a96519744e24fd1dbed2fccc432a2
labs/sysdev-real-time/sysdev-real-time.tex | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/labs/sysdev-real-time/sysdev-real-time.tex b/labs/sysdev-real-time/sysdev-real-time.tex
index d0f4ed1d..2ece8cc3 100644
--- a/labs/sysdev-real-time/sysdev-real-time.tex
+++ b/labs/sysdev-real-time/sysdev-real-time.tex
@@ -159,15 +159,17 @@ Now, do the following tests:
\begin{itemize}
\item Run the \code{rttest} program with nothing special and write
down the results.
-\item Run \code{rttest} again and at the same time, add some workload
- to the board, by running \code{/root/doload 300 > /dev/null 2>&1 &}
+\item Run \code{rttest} once again, but this time
+ using the \code{SCHED_FIFO} scheduling class at priority
+ \code{99}, using the \code{chrt} command. Without this, the kernel
+ doesn't know that your program should be given absolute priority
+ over other processes.
+\item Run \code{rttest} again through \code{chrt}, but right before,
+ add some extra load, by running \code{/root/doload 300 > /dev/null 2>&1 &}
on the board, and using \code{netcat 192.168.0.100 5566} on your
workstation in order to flood the network interface of the Xplained
board (where \code{192.168.0.100} is the IP address of the Xplained
board).
-\item Run \code{rttest} once again with the workload, but by running
- the program in the \code{SCHED_FIFO} scheduling class at priority
- \code{99}, using the \code{chrt} command.
\end{itemize}
\subsection{Testing the preemptible kernel}
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