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2017-10-23 - 10:05
OSADL Projects

OSADL Project: "Latest Stable" PREEMPT_RT realtime Linux kernel

Examples

Stability regression - Latency regressions

Stability regression

The following 1-year recordings of uptime and kernel version have been obtained on a VIA EPIA-V board that is equipped with a CentaurHauls VIA Samuel 2 CPU running at 533 MHz.

Further analysis

There is little doubt that this instability with an average uptime of about 10 days was introduced when upgrading from version 2.6.33.9-rt31 to 3.2.2-rt10. Apparently, the upgrade to version 3.2.23-rt37 did not help.

In order to relate the crashes to certain external conditions, we regularly carry out host alert histogram analyses with respect to day of the month, day of the week and hour of the day:

Day of the month

Day of the week

Hour of the day

Unfortunately, the histogram analyses do not provide any hint towards the origin of the crashes in this particular case, since no time clusters of the crash times can be established.

Conclusion

An instability of unknown origin was introduced when upgrading from the 2.6.x to the 3.x kernel series. Since the system does not produce any output when crashed – even not when forced using a SysRq command – specific hardware instrumentation may be required to elucidate the origin of this instability.