From 0837463f05044535cd512b904e62a4a884322dea Mon Sep 17 00:00:00 2001 From: Bartosz Taudul Date: Tue, 3 Sep 2019 21:45:19 +0200 Subject: [PATCH] Describe how wonderful linux interfaces are. --- manual/tracy.tex | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/manual/tracy.tex b/manual/tracy.tex index 06e5f30e..44efdf1e 100644 --- a/manual/tracy.tex +++ b/manual/tracy.tex @@ -1163,7 +1163,10 @@ noborder=true, couleur=black!5, logo=\bcattention ]{Caveats} -Context switch data is retrieved using the kernel profiling facilities, which are not available to users with normal privilege level. To collect context switches you will need to elevate your rights to admin level, either by running the profiled program from the \texttt{root} account on Unix, or through the \emph{Run as administrator} option on Windows. On Android context switches will be collected if you have a rooted device (see section~\ref{androidlunacy} for additional information). +\begin{itemize} +\item Context switch data is retrieved using the kernel profiling facilities, which are not available to users with normal privilege level. To collect context switches you will need to elevate your rights to admin level, either by running the profiled program from the \texttt{root} account on Unix, or through the \emph{Run as administrator} option on Windows. On Android context switches will be collected if you have a rooted device (see section~\ref{androidlunacy} for additional information). +\item Android context switch capture requires spawning an elevated process to read kernel data (the standard \texttt{cat} utility). Due to the way pipes are handled on Linux, this process will be using quite a lot of system resources, hogging one CPU core most of the time (this time is spent waiting in a busy loop for kernel to generate new data). +\end{itemize} \end{bclogo} \section{Capturing the data}