## Architectures that offer an FUNCTION_TRACER implementation should#  select HAVE_FUNCTION_TRACER:# config USER_STACKTRACE_SUPPORT	bool config NOP_TRACER	bool config HAVE_FUNCTION_TRACER	bool config HAVE_FUNCTION_GRAPH_TRACER	bool config HAVE_FUNCTION_TRACE_MCOUNT_TEST	bool	help	 This gets selected when the arch tests the function_trace_stop	 variable at the mcount call site. Otherwise, this variable	 is tested by the called function. config HAVE_DYNAMIC_FTRACE	bool config HAVE_FTRACE_MCOUNT_RECORD	bool config HAVE_HW_BRANCH_TRACER	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 KALLSYMS	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 FUNCTION_GRAPH_TRACER	bool "Kernel Function Graph Tracer"	depends on HAVE_FUNCTION_GRAPH_TRACER	depends on FUNCTION_TRACER	default y	help	  Enable the kernel to trace a function at both its return	  and its entry.	  It's first purpose is to trace the duration of functions and	  draw a call graph for each thread with some informations like	  the return value.	  This is done by setting the current return address on the current	  task structure into a stack of calls. 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 TRACE_BRANCH_PROFILING	bool "Trace likely/unlikely profiler"	depends on DEBUG_KERNEL	select TRACING	help	  This tracer profiles all the the likely and unlikely macros	  in the kernel. It will display the results in: 	  /debugfs/tracing/profile_annotated_branch 	  Note: this will add a significant overhead, only turn this	  on if you need to profile the system's use of these macros. 	  Say N if unsure. config PROFILE_ALL_BRANCHES	bool "Profile all if conditionals"	depends on TRACE_BRANCH_PROFILING	help	  This tracer profiles all branch conditions. Every if ()	  taken in the kernel is recorded whether it hit or miss.	  The results will be displayed in: 	  /debugfs/tracing/profile_branch 	  This configuration, when enabled, will impose a great overhead	  on the system. This should only be enabled when the system	  is to be analyzed 	  Say N if unsure. config TRACING_BRANCHES	bool	help	  Selected by tracers that will trace the likely and unlikely	  conditions. This prevents the tracers themselves from being	  profiled. Profiling the tracing infrastructure can only happen	  when the likelys and unlikelys are not being traced. config BRANCH_TRACER	bool "Trace likely/unlikely instances"	depends on TRACE_BRANCH_PROFILING	select TRACING_BRANCHES	help	  This traces the events of likely and unlikely condition	  calls in the kernel.  The difference between this and the	  "Trace likely/unlikely profiler" is that this is not a	  histogram of the callers, but actually places the calling	  events into a running trace buffer to see when and where the	  events happened, as well as their results. 	  Say N if unsure. config POWER_TRACER	bool "Trace power consumption behavior"	depends on DEBUG_KERNEL	depends on X86	select TRACING	help	  This tracer helps developers to analyze and optimize the kernels	  power management decisions, specifically the C-state and P-state	  behavior.  config STACK_TRACER	bool "Trace max stack"	depends on HAVE_FUNCTION_TRACER	depends on DEBUG_KERNEL	select FUNCTION_TRACER	select STACKTRACE	select KALLSYMS	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.  If this is configured with DYNAMIC_FTRACE	  then it will not have any overhead while the stack tracer	  is disabled. 	  To enable the stack tracer on bootup, pass in 'stacktrace'	  on the kernel command line. 	  The stack tracer can also be enabled or disabled via the	  sysctl kernel.stack_tracer_enabled 	  Say N if unsure. config HW_BRANCH_TRACER	depends on HAVE_HW_BRANCH_TRACER	bool "Trace hw branches"	select TRACING	help	  This tracer records all branches on the system in a circular	  buffer giving access to the last N branches for each cpu. 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. config MMIOTRACE	bool "Memory mapped IO tracing"	depends on HAVE_MMIOTRACE_SUPPORT && DEBUG_KERNEL && PCI	select TRACING	help	  Mmiotrace traces Memory Mapped I/O access and is meant for	  debugging and reverse engineering. It is called from the ioremap	  implementation and works via page faults. Tracing is disabled by	  default and can be enabled at run-time. 	  See Documentation/tracers/mmiotrace.txt.	  If you are not helping to develop drivers, say N. config MMIOTRACE_TEST	tristate "Test module for mmiotrace"	depends on MMIOTRACE && m	help	  This is a dumb module for testing mmiotrace. It is very dangerous	  as it will write garbage to IO memory starting at a given address.	  However, it should be safe to use on e.g. unused portion of VRAM. 	  Say N, unless you absolutely know what you are doing. endmenu