Rene.B.Wittmann at informatik.stud.uni-erlangen.de
Thu Apr 14 11:21:16 CEST 2005
As I'm trying to implement a real-time application in DROPS, I still
have some questions on this topic. Maybe there's someone who can answer
them because I didn't find it described it the documentation...
1. The timer granularity seems to be set to 976 microsec. Is there a
special background for using this number or can I set it down (maybe
even to 10 microsec, which what be a good time resolution for my task)?
How can I set it? Or would it be stupid to set it to such a tiny value?
2. When looking at the rt_sched example in the hello-package: the
main-thread has a preempter-thread for recognizing timeslice overrun and
deadline misses. When does this preempter-thread recognize a TS overrun
or a deadline miss? Right after this event (so within the next time
resolution) or after the main-thread says that is has finished it's work
(meaning after a call to "l4_rt_next_reservation")?
3. How can the preempter-thread tell the main-thread to stop it's work
in case of a timeslice overrun or even a deadline miss?
4. Does the system allow a thread's scheduling like this:
period-length = 976 microsec,
timeslice_mand = 9760 microsec,
timeslice_opt = 9760 microsec
(which would mean that the system had to reserve timeslices that don't
fit into one period...)
period-length = 9760 microsec,
timeslice_mand = 4380 microsec,
timeslice_opt = 4380 microsec
(which would mean that the system had to reserve all resources for this
(what would happen if another thread comes with a period_length of also
9760 microsec and a timeslice_mand = 6000 microsec? What would be the
File system support:
1. which filesystems are supported (reiserfs?)?
2. Is there a way to have RT access to disk and accessing files this way?
If so, how?
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