Re: [Xenomai-help] gatekeeper/0

[Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>]

henning.richter@domain.hid wrote:
> Hi,
> 
> running a xenomai task in which I am sending a single Frame (size ~500
> byte) from my EtherCAT Master to some Beckhoff slaves has latencies around
> 200 us.
> While running that task, top shows that gatekeeper/0 (with RT priority) has
> 30% CPU usage.
> What is the task of this gatekeeper and can this cause my high latencies?

The gatekeeper is used when a taks is migrating from secondary mode to
primary mode. The gatekeeper itself can not cause the high latencies,
but the fact that a task runs in secondary mode can.

To check if this is what happens, check the MSW column in
/proc/xenomai/stat for the thread which has latencies issues. If MSW is
increasing then you have a problem.

To find where your thread switches to secondary mode, use the technique
demonstrated in examples/native/sigxcpu.c.

-- 
                                                 Gilles.