On Mon, 24 Sep 2007, Cliff Brake wrote:
On 9/24/07, Cliff Brake <cliff.brake@xxxxxxxxx> wrote:
On 9/24/07, Cliff Brake <cliff.brake@xxxxxxxxx> wrote:
On 9/22/07, Arnaldo Carvalho de Melo <acme@xxxxxxxxxxxxxxxxxx> wrote:
Look at the IRQ-<N> kernel thread that services the serial port hardware
interrupt, use chrt to bump its priority and see if it helps.
I don't see any IRQ-<N> processes on my system -- does this require
the RT patch? Perhaps this is different on ARM/x86?
I've applied the RT patch which gives me the IRQ-N processes -- trying now ...
RT patch (2.6.23-rc4-rt1) fixed the problem without any additional
priority adjustments, so that is obviously the solution. I guess I
should know by now that RT with Linux is still hit and miss without
the RT patch.
Yes, that is the point of the -RT patch. Without the patch there are
unbounded code paths running with preemption off. Your maximum jitter thus
highly depends on the complete workload of your system. With the -RT patch
applied there are (almost) no unbounded code paths running with preemption
off. The maximum jitter of a given task will thus only depend on the
workload of the tasks running at the same or higher priority. That is much more
controlable.
Esben
Thanks,
Cliff
--
=======================
Cliff Brake
http://bec-systems.com
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