We are debugging a strange issue with abnormal CPU spikes occurring
in a test application. The test starts a time-constraint thread
running with period = 1000 us, computation = 500 us, constraint =
1000 us. In the test, the thread does nothing but reschedule itself
every 1000 us, basically doing:
while (1) {
next_absolute_name = current_absolute_date (using
"mach_absolute_time" based code) + 1000 us (converted in absolute
date) ;
mach_wait_until(next_absolute_name);
}
(the real code maintains an absolute value incremented exactly by
1000 us to avoid timing deviation...)
On 10.3.9 the average CPU use on a dual G5 is 0%... but we get CPU
spike up to 50-60 % on a dual G5 (up to 90% on the mono G5) every
3-4 minutes in the RT thread.
On 10.4.3, the average CPU use on a dual G5 is now 0.6 %, but there
is no more CPU spike ....
Is this a known issue in 10.3.xxx version of the system?
Thanks
Stephane Letz
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