## Architectures that offer an FUNCTION_TRACER implementation should#  select HAVE_FUNCTION_TRACER:# config NOP_TRACER	bool config HAVE_FUNCTION_TRACER	bool config HAVE_DYNAMIC_FTRACE	bool config HAVE_FTRACE_MCOUNT_RECORD	bool config TRACER_MAX_TRACE	bool config RING_BUFFER	bool config TRACING	bool	select DEBUG_FS	select RING_BUFFER	select STACKTRACE if STACKTRACE_SUPPORT	select TRACEPOINTS	select NOP_TRACER menu "Tracers" config FUNCTION_TRACER	bool "Kernel Function Tracer"	depends on HAVE_FUNCTION_TRACER	depends on DEBUG_KERNEL	select FRAME_POINTER	select TRACING	select CONTEXT_SWITCH_TRACER	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. config IRQSOFF_TRACER	bool "Interrupts-off Latency Tracer"	default n	depends on TRACE_IRQFLAGS_SUPPORT	depends on GENERIC_TIME	depends on DEBUG_KERNEL	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 	  (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	depends on DEBUG_KERNEL	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.) config SYSPROF_TRACER	bool "Sysprof Tracer"	depends on X86	select TRACING	help	  This tracer provides the trace needed by the 'Sysprof' userspace	  tool. config SCHED_TRACER	bool "Scheduling Latency Tracer"	depends on DEBUG_KERNEL	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. config CONTEXT_SWITCH_TRACER	bool "Trace process context switches"	depends on DEBUG_KERNEL	select TRACING	select MARKERS	help	  This tracer gets called from the context switch and records	  all switching of tasks. config BOOT_TRACER	bool "Trace boot initcalls"	depends on DEBUG_KERNEL	select TRACING	select CONTEXT_SWITCH_TRACER	help	  This tracer helps developers to optimize boot times: it records	  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. ) config STACK_TRACER	bool "Trace max stack"	depends on HAVE_FUNCTION_TRACER	depends on DEBUG_KERNEL	select FUNCTION_TRACER	select STACKTRACE	help	  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. config DYNAMIC_FTRACE	bool "enable/disable ftrace tracepoints dynamically"	depends on FUNCTION_TRACER	depends on HAVE_DYNAMIC_FTRACE	depends on DEBUG_KERNEL	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. 	 This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but otherwise	 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. config FTRACE_MCOUNT_RECORD	def_bool y	depends on DYNAMIC_FTRACE	depends on HAVE_FTRACE_MCOUNT_RECORD config FTRACE_SELFTEST	bool config FTRACE_STARTUP_TEST	bool "Perform a startup test on ftrace"	depends on TRACING && DEBUG_KERNEL && !BOOT_TRACER	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. endmenu