Note sure how that is possible. This is related to my earlier posting
about timing jitter. Our code is basically this:
while(1)
{
t1 = clock_gettime()
for(i=0; i < 10000; i++)
t2 = clock_gettime()
diff = t2 - 1
}
This task is pending on nothing. Unless clock_gettime() causes some
sort of priority inversion, I don't see the problem. We see
significant jitter on the for-loop when there are a significant number
of other kernel timers. Now, as we understand it, the hrtimers run in
the softirq. But if the softirq is priority 50, and this for-loop is
priority 99, it shouldn't be affected by the softirq thread.
Pete
On Mon, Feb 14, 2011 at 3:04 PM, Sven-Thorsten Dietrich
<thebigcorporation@xxxxxxxxx> wrote:
> On Mon, 2011-02-14 at 14:31 -0800, Peter LaDow wrote:
>> How is the scheduling of the hrtimers softirq thread handled?
>>
>> When querying the RT priority of the hrtimer softirq, I get a priority
>> of 50. But when running a priority 99 thread, we still seem to be
>> getting interrupted. Shouldn't the hrtimer softirq be put off until
>> the CPU is idle or a lower priority task is running?
>
> Does your prio 99 thread perhaps encounter a prio inversion dependency
> on one of the softriq threads?
>
>>
>> Thanks,
>> Pete
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