Re: Worst case execution time problem


Randy Howard wrote:
On Sat, 30 Dec 2006 11:31:52 -0600, gw7rib@xxxxxxx wrote
(in article <1167499912.126975.59540@xxxxxxxxxxxxxxxxxxxxxxxxxxx>):


Christian Christmann wrote:
Hi,

in real-time systems the worst case execution time (WCET) is an important
issue. In the literature I found the statement that its calculation is
undecidable in general. Why? I appreciate any detailed explanations.

Perhaps an example will help.

We're talking a program running in an OS along with other tasks, kernel
code and device drivers though. Such simplifications are fine for CS
class, but not for measuring WCET in a real-time system.

[Snip example]

How long does this program take to run?

Now what's the right answer?

I was trying to make the point that even for a simple program, like the
one I demonstrated, it is not possible to work out the WCET. Adding
additional unspecified delays won't make it any easier to work out the
WCET so I'm not quite sure what you're driving at.

.

Relevant Pages

  • Re: Worst case execution time problem
    ... Christian Christmann wrote: ... in real-time systems the worst case execution time is an important ... We're talking a program running in an OS along with other tasks, ... but not for measuring WCET in a real-time system. ...
    (comp.programming)
  • Re: Worst case execution time problem
    ... Christian Christmann wrote: ... in real-time systems the worst case execution time is an important ... In the literature I found the statement that its calculation is ... but not for measuring WCET in a real-time system. ...
    (comp.programming)