diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 19 | ||||
| -rw-r--r-- | Documentation/trace/histogram.rst | 10 | ||||
| -rw-r--r-- | Documentation/trace/osnoise-tracer.rst | 32 |
3 files changed, 58 insertions, 3 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index fb388c6c8c60..5a0eff3231c6 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -6266,6 +6266,25 @@ See also Documentation/trace/ftrace.rst "trace options" section. + trace_trigger=[trigger-list] + [FTRACE] Add a event trigger on specific events. + Set a trigger on top of a specific event, with an optional + filter. + + The format is is "trace_trigger=<event>.<trigger>[ if <filter>],..." + Where more than one trigger may be specified that are comma deliminated. + + For example: + + trace_trigger="sched_switch.stacktrace if prev_state == 2" + + The above will enable the "stacktrace" trigger on the "sched_switch" + event but only trigger it if the "prev_state" of the "sched_switch" + event is "2" (TASK_UNINTERUPTIBLE). + + See also "Event triggers" in Documentation/trace/events.rst + + traceoff_on_warning [FTRACE] enable this option to disable tracing when a warning is hit. This turns off "tracing_on". Tracing can diff --git a/Documentation/trace/histogram.rst b/Documentation/trace/histogram.rst index 87bd772836c0..f95459aa984f 100644 --- a/Documentation/trace/histogram.rst +++ b/Documentation/trace/histogram.rst @@ -25,7 +25,7 @@ Documentation written by Tom Zanussi hist:keys=<field1[,field2,...]>[:values=<field1[,field2,...]>] [:sort=<field1[,field2,...]>][:size=#entries][:pause][:continue] - [:clear][:name=histname1][:<handler>.<action>] [if <filter>] + [:clear][:name=histname1][:nohitcount][:<handler>.<action>] [if <filter>] When a matching event is hit, an entry is added to a hash table using the key(s) and value(s) named. Keys and values correspond to @@ -79,6 +79,8 @@ Documentation written by Tom Zanussi .log2 display log2 value rather than raw number .buckets=size display grouping of values rather than raw number .usecs display a common_timestamp in microseconds + .percent display a number of percentage value + .graph display a bar-graph of a value ============= ================================================= Note that in general the semantics of a given field aren't @@ -137,6 +139,12 @@ Documentation written by Tom Zanussi existing trigger, rather than via the '>' operator, which will cause the trigger to be removed through truncation. + The 'nohitcount' (or NOHC) parameter will suppress display of + raw hitcount in the histogram. This option requires at least one + value field which is not a 'raw hitcount'. For example, + 'hist:...:vals=hitcount:nohitcount' is rejected, but + 'hist:...:vals=hitcount.percent:nohitcount' is OK. + - enable_hist/disable_hist The enable_hist and disable_hist triggers can be used to have one 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. |