Hi, there!
I have installed the RT_PREEMPT patch v2.6.23.11-rt4 and now try to
verify my installation. Therefore I used cyclictest with clock_nanosleep
and clock_monotonic options for 5-50 threads. The results are shown below:
#Threads Minimum (microsec) Average (microsec) Maximum (microsec)
5 5 6 45
10 4 5 31
15 5 5 33
20 4 6 37
25 5 6 52
30 5 6 63
35 5 6 71
40 6 6 62
45 5 6 88
50 5 7 96
An Intel Pentium 4, 2.8GHz clock speed with 1GB main memory was used for
the benchmark.
Now my questions:
1. The maximum thread latency does not scale linear. Why?
2. RT is a synonym for determinism, but the maximum latency for each
number of threads fluctuate in each repetition of the benchmark.
Therefore I guess that no worst-case delay can be predicted, right?
3. Does RT-Linux support hard real-time at all? With the results shown
above, only soft real-time is supported (deadline 6us).
4. How can I verify - if at all - that my installation supports soft
real-time or better hard real-time?
Thanks for your help!
Markus
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