Messages in this thread | | | Date | Sun, 12 Jun 2005 08:11:08 +0200 | From | Ingo Molnar <> | Subject | Re: PREEMPT_RT vs ADEOS: the numbers, part 1 |
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* Karim Yaghmour <karim@opersys.com> wrote:
> Ingo Molnar wrote: > > how were interrupt response times measured, precisely? What did the > > target (measured) system have to do to respond to an interrupt? Did you > > use the RTC to measure IRQ latencies? > > The logger used two TSC values. One prior to shooting the interrupt to > the target, and one when receiving the response. Responding to an > interrupt meant that a driver was hooked to the target's parallel port > interrupt and simply acted by toggling an output pin on the parallel > port, which in turn was hooked onto the logger's parallel port in a > similar fashion. We'll post the code for all components (both logger > and target) for everyone to review. There's no validity in any tests > if others can't analyze/criticize/ duplicate.
ok, this method should work fine. I suspect you increased the parport IRQ's priority to the maximum on the PREEMPT_RT kernel, correct? Was there any userspace thread on the target system (receiving the parport request and sending the reply), or was it all done in a kernelspace parport driver?
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