> Hmm, I should have better said "tiny". This experience is based on
> I-pipe tracer observations, and I guess you don't have that thing on,
> have you?

I have set:

---snip---
# CONFIG_IPIPE_DEBUG is not set
CONFIG_IPIPE_TRACE_ENABLE_VALUE=0
---snap---

in both kernels (either with preempt or without).

> How much is the difference? How long did you measure to exclude noise.

The difference is about 1 us (in average and worst case) when running
irqloop in IRQ handler mode.

I have been running the measurements for 1 minute under heavy load with
an interrupt frequency of 1 ms. This gives 60000 samples. Is this too
less in order to exclude noise?


Regards,
Markus Franke