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Diffstat (limited to 'Documentation/trace/osnoise-tracer.rst')
| -rw-r--r-- | Documentation/trace/osnoise-tracer.rst | 32 |
1 files changed, 30 insertions, 2 deletions
diff --git a/Documentation/trace/osnoise-tracer.rst b/Documentation/trace/osnoise-tracer.rst index 963def9f97c6..140ef2533d26 100644 --- a/Documentation/trace/osnoise-tracer.rst +++ b/Documentation/trace/osnoise-tracer.rst @@ -92,8 +92,8 @@ Note that the example above shows a high number of HW noise samples. The reason being is that this sample was taken on a virtual machine, and the host interference is detected as a hardware interference. -Tracer options ---------------------- +Tracer Configuration +-------------------- The tracer has a set of options inside the osnoise directory, they are: @@ -109,6 +109,27 @@ The tracer has a set of options inside the osnoise directory, they are: - tracing_threshold: the minimum delta between two time() reads to be considered as noise, in us. When set to 0, the default value will be used, which is currently 5 us. + - osnoise/options: a set of on/off options that can be enabled by + writing the option name to the file or disabled by writing the option + name preceded with the 'NO\_' prefix. For example, writing + NO_OSNOISE_WORKLOAD disables the OSNOISE_WORKLOAD option. The + special DEAFAULTS option resets all options to the default value. + +Tracer Options +-------------- + +The osnoise/options file exposes a set of on/off configuration options for +the osnoise tracer. These options are: + + - DEFAULTS: reset the options to the default value. + - OSNOISE_WORKLOAD: do not dispatch osnoise workload (see dedicated + section below). + - PANIC_ON_STOP: call panic() if the tracer stops. This option serves to + capture a vmcore. + - OSNOISE_PREEMPT_DISABLE: disable preemption while running the osnoise + workload, allowing only IRQ and hardware-related noise. + - OSNOISE_IRQ_DISABLE: disable IRQs while running the osnoise workload, + allowing only NMIs and hardware-related noise, like hwlat tracer. Additional Tracing ------------------ @@ -150,3 +171,10 @@ tracepoints is smaller than eight us reported in the sample_threshold. The reason roots in the overhead of the entry and exit code that happens before and after any interference execution. This justifies the dual approach: measuring thread and tracing. + +Running osnoise tracer without workload +--------------------------------------- + +By enabling the osnoise tracer with the NO_OSNOISE_WORKLOAD option set, +the osnoise: tracepoints serve to measure the execution time of +any type of Linux task, free from the interference of other tasks. |