From 9f6398676910a35847f114b8c3f3ca53af134d0b Mon Sep 17 00:00:00 2001
From: guest <guest@da047780-0f9f-48de-953f-cd541ee48bbd>
Date: Thu, 11 Oct 2007 16:45:11 +0000
Subject: started section operating system needs

git-svn-id: svn+ssh://mecka.net/home/svn/rtcorba-paper@9 da047780-0f9f-48de-953f-cd541ee48bbd
---
 paper.tex | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

(limited to 'paper.tex')

diff --git a/paper.tex b/paper.tex
index 9cda653..08fa6f6 100755
--- a/paper.tex
+++ b/paper.tex
@@ -165,17 +165,6 @@ To simulate the transmission of bigger process data images, the parameter \texti
 
 \epsin{sequenzV1}{80}{fig1:f5}{RPC measurement: sequence diagramm}
 
-For testing the priorization based scheduling, the following interface was added:
-
-\begin{lstlisting}
-  interface Data{
-    void Send(in string data);
-  };
-\end{lstlisting}
-
-Each time \textit{Send} was called, the Receiver did a calculation of faculty(100). The \textit{Data} interface was hosted with lower priority, then the Put interface.
-
-
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %% SUB SECTION (OPTIONAL)
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -192,6 +181,12 @@ As soon as the value of the digital input of the Supplier changes, the new value
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \section{Needed operating system functionalities}
 
+An TAO ORB can only schedule its CORBA requests correctly, if the underlying operating system has an priorization based scheduler, with a defined maximum scheduling latency. The timer and scheduling latency of a linux system can be determined with cyclictest. For example, the worst case latency on a RT\_PREEMPT enabled box is $26 \mu s$. The same test, on the same box, but with RT\_PREEMPT disabled is $39.6 ms$.
+
+The operating system should support priorization of device i/o data. The real-time application must not beeing interrupted by incomming traffic on any device, excepted data the real-time application must react on (e.g. digital inputs). On a RT\_PREEMPT enabled linux, the most part of all ISR\footnote{interrupt service routine}s are done in kernel threads, which can be priorized from userspace. This solution has two little cons: IRQ sharing and the softirqs for networking. IRQ sharing prevents from a real per device priorization. The softirqs for networking handle the traffic of all NICs in the system. So the priorization of network data from a specific device is not possible. But in case real-time networking gets more and more important, the community works on a solution for this issue.
+
+real-time capable network drivers
+
 
 \section{Conclusion}
 
-- 
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