[bootlin/training-materials updates] master: Boot time labs: use rw path for strace output files (d172bfcd)
Michael Opdenacker
michael.opdenacker at bootlin.com
Tue Jun 22 18:21:51 CEST 2021
Repository : https://github.com/bootlin/training-materials
On branch : master
Link : https://github.com/bootlin/training-materials/commit/d172bfcda9e6d37620821837d932e51cd0243bb1
>---------------------------------------------------------------
commit d172bfcda9e6d37620821837d932e51cd0243bb1
Author: Michael Opdenacker <michael.opdenacker at bootlin.com>
Date: Tue Jun 22 18:17:52 2021 +0200
Boot time labs: use rw path for strace output files
Taking advantage of the fact that Buildroot mounts /tmp
as a tmpfs
Signed-off-by: Michael Opdenacker <michael.opdenacker at bootlin.com>
>---------------------------------------------------------------
d172bfcda9e6d37620821837d932e51cd0243bb1
labs/boot-time-application/boot-time-application.tex | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/labs/boot-time-application/boot-time-application.tex b/labs/boot-time-application/boot-time-application.tex
index 851e10ca..caee8a8d 100644
--- a/labs/boot-time-application/boot-time-application.tex
+++ b/labs/boot-time-application/boot-time-application.tex
@@ -165,17 +165,17 @@ Once the board has booted, run \code{strace} on the video player
application:
\begin{verbatim}
-strace -tt -f -o strace.log ffmpeg -f video4linux2 -video_size 544x288 \
+strace -tt -f -o /tmp/strace.log ffmpeg -f video4linux2 -video_size 544x288 \
-input_format mjpeg -i /dev/video0 -pix_fmt rgb565le -f fbdev /dev/fb0
\end{verbatim}
Also have \code{strace} generate a summary:
\begin{verbatim}
-strace -c -f -o strace-summary.log ffmpeg ...
+strace -c -f -o /tmp/strace-summary.log ffmpeg ...
\end{verbatim}
-Take some time to read \code{strace.log}\footnote{
+Take some time to read \code{/tmp/strace.log}\footnote{
At this stage, when you have to open files directly on the
board, some familiarity with the basic commands of the \code{vi} editor
becomes useful. See
@@ -186,7 +186,7 @@ example.}, and see everything that the program is doing. Don't hesitate
to lookup the ioctl codes on the Internet to have an idea about what's
going on between the player, the camera and the display.
-Also have a look at \code{strace-summary.log}. You will find the number
+Also have a look at \code{/tmp/strace-summary.log}. You will find the number
of errors trying to open files that do not exist, and where most time is
spent, for example. You can also count the number of memory allocations
(using the \code{mmap2} system call).
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