Hello everyone,
[ Please include my address in the CC list ]
I have been experimenting with the CONFIG_PREEMPT_RT patch for a few
months. Specifically kernel 2.6.20.7-rt8.
http://rt.wiki.kernel.org/index.php/Main_Page
I've been running into some unexpected problems, so I wanted to ask
those who have some experience with this patch what they thought.
Here's a brief description of my application:
System A periodically sends timestamped packets. These packets travel
over a network, or through a network emulator, and get randomly dropped
or delayed by a random amount of time. These packets reach system B at
some point. System B uses the timestamp to re-send the packets smoothly,
as if they had been produced on B, with only a constant time-shift.
Basically, B acts as a "dejittering" router.
I have implemented this with high-resolution timers. Every time the
timer fires, I send one packet. In "parallel", I buffer incoming packets
that arrive from system A.
Consider 1316-byte packets and a 80 Mbit/s stream bit rate.
This means the timer period is 1316*8 / 80 = 131.6 µs
I've been wondering whether having such a small period (high frequency)
might be a problem / challenge for the real-time kernel (scheduler, IRQ
handler, other component).
The CPUs used are mid-range (i.e. 1.3 GHz P3 and 1.5 GHz Celeron M)
single core, and they easily copes with just the receiving part.
But I have seen some odd behavior (random crashes in my program) that
must mean I have made some incorrect assumptions.
What do you all think?
Regards.
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