domain switch

Philippe Gerum rpm at
Sun Jan 3 11:31:34 CET 2021

steve freyder via Xenomai <xenomai at> writes:

> Right.
> AKA, "mode switch", a switch from "primary mode" to "secondary mode",
> or vice versa.
> One place you can find that information is in:
> /proc/xenomai/sched/acct
> there are two fields MSW, and CSW which count mode/context switches
> per-process. This requires an open, a read loop to locate the desired 
> pid and extract the desired information, then either rewind or
> close/reopen to do it again - all of which will almost surely generate 
> more mode/context switching.

If that helps, there is also the option of getting the thread stats by
program, using int cobalt_thread_stat(pid_t pid, struct
cobalt_threadstat *stat), declared in sys/cobalt.h. pid refers to a
thread identifier (as obtained from gettid(2) in the context of the
target thread). It must refer to a Cobalt thread, otherwise the call
would fail with -ESRCH.

The mode switch count is present in the returned information block
(->msw). cobalt_thread_stat() would not cause any mode switch. It can be
called by any thread regardless of its type (i.e. regular or Cobalt).


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