Hello
I've been running real time threads under Linux (kernel 2.4.0-test10),
using SCHED_FIFO policy in order to try to describe temporal behavior of
these tasks under Linux (not real time linux). The threads use the highest
priority allowed for the scheduller (5 threads, 5 different priorities)
and each of the five threads implemented use the same code but different
periods.
Periods are determined by nanosleep call, which is called using a
different time amount parameter according to each thread's chosen period.
My idea was to see how these tasks were treated by Linux, through the
analysis of the time interval caught in each instances of the tasks
executed (response time: instant of task's execution conclusion -
instant of task arrival).
Well after adjusting the nanosleep time amount paramenter (in order to
get a more precise sleep period), the response times got were closer to
the expected.
But sometimes, like coming from nowhere, one instance of the
experiment returns a time value much higher than the rest.
(ex: when most of the values are 67us, this particular instance returns
20ms). And I just can't imagine what it could be!! All I know is that it
is caused by the nanosleep call, which, despite being called with a time
parameter very close to the rest of the instances, takes much more time in
sleep..
It has happens once in each experiment (first task with 3000 instances /
period = 50ms), and sometimes it just don't happen...
Would anyone have a clue of what could it be?
The code of my little program can be downloaded in
http:\\www.lcmi.ufsc.br\~cytatiba
the file is tr5.c
Thank you so much!
Cassia Yuri Tatibana
<[EMAIL PROTECTED]>
"Life is hard,
after all it kills you."
Katherine Hepburn
-- [rtl] ---
To unsubscribe:
echo "unsubscribe rtl" | mail [EMAIL PROTECTED] OR
echo "unsubscribe rtl <Your_email>" | mail [EMAIL PROTECTED]
--
For more information on Real-Time Linux see:
http://www.rtlinux.org/
