realtime:documentation:howto:tools:cyclictest:tracing
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realtime:documentation:howto:tools:cyclictest:tracing [2022/01/19 19:56] bartwensley [Selecting Instrumentation] Cyclictest no longer configures ftrace (since rt-tests version 1.4) |
realtime:documentation:howto:tools:cyclictest:tracing [2022/01/19 20:01] (current) bartwensley [Producing a Trace] Removed --ftrace option which has not been supported since rt-tests version 1.4. |
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| </code> | </code> | ||
| - | and after a couple hours a maximum latency of 130 us is detected. To measure the value of the maximum latency with the overhead from function tracing, the following Cyclictest command could be run: | + | and after a couple hours a maximum latency of 130 us is detected. To measure the value of the maximum latency with the overhead from function tracing, ftrace can be enabled and then the following Cyclictest command could be run: |
| <code bash> | <code bash> | ||
| - | cyclictest --mlockall --smp --priority=80 --interval=200 --distance=0 --breaktrace=2000 --ftrace | + | cyclictest --mlockall --smp --priority=80 --interval=200 --distance=0 --breaktrace=2000 --tracemark |
| </code> | </code> | ||
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| ==== Producing a Trace ==== | ==== Producing a Trace ==== | ||
| - | Finally, a trace that includes the latency can be produced by running Cyclictest with a break trace limit that is slightly below the maximum latency value that was observed with tracing enabled. Continuing the example from the previous section, if the maximum latency with the overhead from function tracing is 190 us then the following command could be used to produce the trace: | + | Finally, a trace that includes the latency can be produced by starting ftrace and then running Cyclictest with a break trace limit that is slightly below the maximum latency value that was observed with tracing enabled. Continuing the example from the previous section, if the maximum latency with the overhead from function tracing is 190 us then the following command could be used to produce the trace: |
| <code bash> | <code bash> | ||
| - | cyclictest --mlockall --smp --priority=80 --interval=200 --distance=0 --breaktrace=180 --ftrace | + | cyclictest --mlockall --smp --priority=80 --interval=200 --distance=0 --breaktrace=180 --tracemark |
| </code> | </code> | ||
| using a break trace limit of 180 us. This new limit will cause Cyclictest to stop when the maximum latency occurs and will produce the relevant trace. This trace can then be viewed via tracefs in the same way as other Ftrace traces. | using a break trace limit of 180 us. This new limit will cause Cyclictest to stop when the maximum latency occurs and will produce the relevant trace. This trace can then be viewed via tracefs in the same way as other Ftrace traces. | ||
realtime/documentation/howto/tools/cyclictest/tracing.1642622219.txt.gz ยท Last modified: 2022/01/19 19:56 by bartwensley
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