On 09/01/2015 02:27 PM, Dmitriy Cherkasov wrote: > We have seen this before, but so far have not found a way to consistently > reproduce it. > > There are some caveats with the current way context switching is done in > Xenomai. > > On armv7, there was a completely separate implementation of > xnarch_switch_to(), > as well as separate fpu and TLS switching. At this stage for armv8 however, we > are doing a direct call to the kernel's __switch_to(), which then performs the > relevant register switches. > > Another possibility is that this may be lurking in the mm switch. During > calls > to check_and_switch_context(), the interrupt state may not always > match what is expected according to the comments in the original > version of that function. > > Overall, this mechanism could definitely benefit from further review. >
Thanks Dimitry. I'll also try to look into this for this specific platform (however I am hopping that either Gilles or Philippe can spend some time on this soon) Just for completeness, as things stand this is pretty much that value I am seeing over consecutive runs. RTD| 4.167| 6.099| 11.667| 0| 0| 3.333| 66.667 RTD| 4.167| 6.217| 13.333| 0| 0| 3.333| 66.667 RTD| 4.167| 6.259| 11.667| 0| 0| 3.333| 66.667 RTD| 4.167| 6.226| 12.500| 0| 0| 3.333| 66.667 RTD| 4.167| 6.105| 11.667| 0| 0| 3.333| 66.667 RTD| 4.167| 6.181| 12.500| 0| 0| 3.333| 66.667 RTD| 4.167| 6.232| 12.500| 0| 0| 3.333| 66.667 RTD| 4.167| 6.483| 20.000| 0| 0| 3.333| 66.667 RTD| 4.167| 6.409| 9.167| 0| 0| 3.333| 66.667 RTD| 4.167| 5.707| 12.500| 0| 0| 3.333| 66.667 RTD| 4.167| 5.026| 6.667| 0| 0| 3.333| 66.667 RTT| 00:15:04 (periodic user-mode task, 1000 us period, priority 99) RTH|----lat min|----lat avg|----lat max|-overrun|---msw|---lat best|--lat worst RTD| 4.167| 5.025| 6.667| 0| 0| 3.333| 66.667 Load script terminated, terminating checked scripts ---|-----------|-----------|-----------|--------|------|------------------------- RTS| 3.333| 6.540| 66.667| 0| 0| 00:15:04/00:15:04 pipe_in: /tmp/xeno-test-in-9797 -- jro _______________________________________________ Xenomai mailing list Xenomai@xenomai.org http://xenomai.org/mailman/listinfo/xenomai
