Kconfig 5.6 KB
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#
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# Architectures that offer an FUNCTION_TRACER implementation should
#  select HAVE_FUNCTION_TRACER:
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#
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config NOP_TRACER
	bool

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config HAVE_FUNCTION_TRACER
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	bool
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	select NOP_TRACER
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config HAVE_DYNAMIC_FTRACE
	bool

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config HAVE_FTRACE_MCOUNT_RECORD
	bool

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config TRACER_MAX_TRACE
	bool

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config RING_BUFFER
	bool

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config TRACING
	bool
	select DEBUG_FS
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	select RING_BUFFER
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	select STACKTRACE
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	select TRACEPOINTS
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config FUNCTION_TRACER
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	bool "Kernel Function Tracer"
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	depends on HAVE_FUNCTION_TRACER
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	depends on DEBUG_KERNEL
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	select FRAME_POINTER
	select TRACING
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	select CONTEXT_SWITCH_TRACER
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	help
	  Enable the kernel to trace every kernel function. This is done
	  by using a compiler feature to insert a small, 5-byte No-Operation
	  instruction to the beginning of every kernel function, which NOP
	  sequence is then dynamically patched into a tracer call when
	  tracing is enabled by the administrator. If it's runtime disabled
	  (the bootup default), then the overhead of the instructions is very
	  small and not measurable even in micro-benchmarks.
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config IRQSOFF_TRACER
	bool "Interrupts-off Latency Tracer"
	default n
	depends on TRACE_IRQFLAGS_SUPPORT
	depends on GENERIC_TIME
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	depends on DEBUG_KERNEL
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	select TRACE_IRQFLAGS
	select TRACING
	select TRACER_MAX_TRACE
	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 > /debugfs/tracing/tracing_max_latency

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	  (Note that kernel size and overhead increases with this option
	  enabled. This option and the preempt-off timing option can be
	  used together or separately.)

config PREEMPT_TRACER
	bool "Preemption-off Latency Tracer"
	default n
	depends on GENERIC_TIME
	depends on PREEMPT
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	depends on DEBUG_KERNEL
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	select TRACING
	select TRACER_MAX_TRACE
	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 > /debugfs/tracing/tracing_max_latency

	  (Note that kernel size and overhead increases with this option
	  enabled. This option and the irqs-off timing option can be
	  used together or separately.)

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config SYSPROF_TRACER
	bool "Sysprof Tracer"
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	depends on X86
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	select TRACING
	help
	  This tracer provides the trace needed by the 'Sysprof' userspace
	  tool.

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config SCHED_TRACER
	bool "Scheduling Latency Tracer"
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	depends on DEBUG_KERNEL
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	select TRACING
	select CONTEXT_SWITCH_TRACER
	select TRACER_MAX_TRACE
	help
	  This tracer tracks the latency of the highest priority task
	  to be scheduled in, starting from the point it has woken up.

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config CONTEXT_SWITCH_TRACER
	bool "Trace process context switches"
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	depends on DEBUG_KERNEL
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	select TRACING
	select MARKERS
	help
	  This tracer gets called from the context switch and records
	  all switching of tasks.

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config BOOT_TRACER
	bool "Trace boot initcalls"
	depends on DEBUG_KERNEL
	select TRACING
	help
	  This tracer helps developers to optimize boot times: it records
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	  the timings of the initcalls and traces key events and the identity
	  of tasks that can cause boot delays, such as context-switches.

	  Its aim is to be parsed by the /scripts/bootgraph.pl tool to
	  produce pretty graphics about boot inefficiencies, giving a visual
	  representation of the delays during initcalls - but the raw
	  /debug/tracing/trace text output is readable too.

	  ( Note that tracing self tests can't be enabled if this tracer is
	    selected, because the self-tests are an initcall as well and that
	    would invalidate the boot trace. )
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config STACK_TRACER
	bool "Trace max stack"
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	depends on HAVE_FUNCTION_TRACER
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	depends on DEBUG_KERNEL
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	select FUNCTION_TRACER
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	select STACKTRACE
	help
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	  This special tracer records the maximum stack footprint of the
	  kernel and displays it in debugfs/tracing/stack_trace.

	  This tracer works by hooking into every function call that the
	  kernel executes, and keeping a maximum stack depth value and
	  stack-trace saved. Because this logic has to execute in every
	  kernel function, all the time, this option can slow down the
	  kernel measurably and is generally intended for kernel
	  developers only.

	  Say N if unsure.
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config DYNAMIC_FTRACE
	bool "enable/disable ftrace tracepoints dynamically"
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	depends on FUNCTION_TRACER
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	depends on HAVE_DYNAMIC_FTRACE
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	depends on DEBUG_KERNEL
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	default y
	help
         This option will modify all the calls to ftrace dynamically
	 (will patch them out of the binary image and replaces them
	 with a No-Op instruction) as they are called. A table is
	 created to dynamically enable them again.

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	 This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but otherwise
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	 has native performance as long as no tracing is active.

	 The changes to the code are done by a kernel thread that
	 wakes up once a second and checks to see if any ftrace calls
	 were made. If so, it runs stop_machine (stops all CPUS)
	 and modifies the code to jump over the call to ftrace.
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config FTRACE_MCOUNT_RECORD
	def_bool y
	depends on DYNAMIC_FTRACE
	depends on HAVE_FTRACE_MCOUNT_RECORD

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config FTRACE_SELFTEST
	bool

config FTRACE_STARTUP_TEST
	bool "Perform a startup test on ftrace"
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	depends on TRACING && DEBUG_KERNEL && !BOOT_TRACER
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	select FTRACE_SELFTEST
	help
	  This option performs a series of startup tests on ftrace. On bootup
	  a series of tests are made to verify that the tracer is
	  functioning properly. It will do tests on all the configured
	  tracers of ftrace.