+
+config KERNEL_IRQSOFF_TRACER
+ bool "Interrupts-off Latency Tracer"
+ depends on KERNEL_FTRACE
+ help
+ This option measures the time spent in irqs-off critical
+ sections, with microsecond accuracy.
+
+ The default measurement method is a maximum search, which is
+ disabled by default and can be runtime (re-)started
+ via:
+
+ echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
+
+ (Note that kernel size and overhead increase with this option
+ enabled. This option and the preempt-off timing option can be
+ used together or separately.)
+
+config KERNEL_PREEMPT_TRACER
+ bool "Preemption-off Latency Tracer"
+ depends on KERNEL_FTRACE
+ help
+ This option measures the time spent in preemption-off critical
+ sections, with microsecond accuracy.
+
+ The default measurement method is a maximum search, which is
+ disabled by default and can be runtime (re-)started
+ via:
+
+ echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
+
+ (Note that kernel size and overhead increase with this option
+ enabled. This option and the irqs-off timing option can be
+ used together or separately.)
+
+config KERNEL_HIST_TRIGGERS
+ bool "Histogram triggers"
+ depends on KERNEL_FTRACE
+ help
+ Hist triggers allow one or more arbitrary trace event fields to be
+ aggregated into hash tables and dumped to stdout by reading a
+ debugfs/tracefs file. They're useful for gathering quick and dirty
+ (though precise) summaries of event activity as an initial guide for
+ further investigation using more advanced tools.
+
+ Inter-event tracing of quantities such as latencies is also
+ supported using hist triggers under this option.