linux-yocto/kernel/trace/Kconfig

Architectures that offer an FUNCTION_TRACER implementation should

select HAVE_FUNCTION_TRACER:

config USER_STACKTRACE_SUPPORT bool

config NOP_TRACER bool

config HAVE_FTRACE_NMI_ENTER bool help See Documentation/trace/ftrace-design.txt

config HAVE_FUNCTION_TRACER bool help See Documentation/trace/ftrace-design.txt

config HAVE_FUNCTION_GRAPH_TRACER bool help See Documentation/trace/ftrace-design.txt

config HAVE_FUNCTION_GRAPH_FP_TEST bool help See Documentation/trace/ftrace-design.txt

config HAVE_FUNCTION_TRACE_MCOUNT_TEST bool help See Documentation/trace/ftrace-design.txt

config HAVE_DYNAMIC_FTRACE bool help See Documentation/trace/ftrace-design.txt

config HAVE_DYNAMIC_FTRACE_WITH_REGS bool

config HAVE_FTRACE_MCOUNT_RECORD bool help See Documentation/trace/ftrace-design.txt

config HAVE_SYSCALL_TRACEPOINTS bool help See Documentation/trace/ftrace-design.txt

config HAVE_FENTRY bool help Arch supports the gcc options -pg with -mfentry

config HAVE_C_RECORDMCOUNT bool help C version of recordmcount available?

config TRACER_MAX_TRACE bool

config TRACE_CLOCK bool

config RING_BUFFER bool select TRACE_CLOCK

config FTRACE_NMI_ENTER bool depends on HAVE_FTRACE_NMI_ENTER default y

config EVENT_TRACING select CONTEXT_SWITCH_TRACER bool

config CONTEXT_SWITCH_TRACER bool

config RING_BUFFER_ALLOW_SWAP bool help Allow the use of ring_buffer_swap_cpu. Adds a very slight overhead to tracing when enabled.

All tracer options should select GENERIC_TRACER. For those options that are

enabled by all tracers (context switch and event tracer) they select TRACING.

This allows those options to appear when no other tracer is selected. But the

options do not appear when something else selects it. We need the two options

GENERIC_TRACER and TRACING to avoid circular dependencies to accomplish the

hiding of the automatic options.

config TRACING bool select DEBUG_FS select RING_BUFFER select STACKTRACE if STACKTRACE_SUPPORT select TRACEPOINTS select NOP_TRACER select BINARY_PRINTF select EVENT_TRACING select TRACE_CLOCK select IRQ_WORK

config GENERIC_TRACER bool select TRACING

Minimum requirements an architecture has to meet for us to

be able to offer generic tracing facilities:

config TRACING_SUPPORT bool # PPC32 has no irqflags tracing support, but it can use most of the # tracers anyway, they were tested to build and work. Note that new # exceptions to this list aren't welcomed, better implement the # irqflags tracing for your architecture. depends on TRACE_IRQFLAGS_SUPPORT || PPC32 depends on STACKTRACE_SUPPORT default y

if TRACING_SUPPORT

menuconfig FTRACE bool "Tracers" default y if DEBUG_KERNEL help Enable the kernel tracing infrastructure.

if FTRACE

config FUNCTION_TRACER bool "Kernel Function Tracer" depends on HAVE_FUNCTION_TRACER select KALLSYMS select GENERIC_TRACER 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 at 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 depends on !X86_32 || !CC_OPTIMIZE_FOR_SIZE default y help Enable the kernel to trace a function at both its return and its entry. Its first purpose is to trace the duration of functions and draw a call graph for each thread with some information 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 !ARCH_USES_GETTIMEOFFSET select TRACE_IRQFLAGS select GENERIC_TRACER select TRACER_MAX_TRACE select RING_BUFFER_ALLOW_SWAP 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 PREEMPT_TRACER bool "Preemption-off Latency Tracer" default n depends on !ARCH_USES_GETTIMEOFFSET depends on PREEMPT select GENERIC_TRACER select TRACER_MAX_TRACE select RING_BUFFER_ALLOW_SWAP 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 SCHED_TRACER bool "Scheduling Latency Tracer" select GENERIC_TRACER 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 ENABLE_DEFAULT_TRACERS bool "Trace process context switches and events" depends on !GENERIC_TRACER select TRACING help This tracer hooks to various trace points in the kernel, allowing the user to pick and choose which trace point they want to trace. It also includes the sched_switch tracer plugin.

config FTRACE_SYSCALLS bool "Trace syscalls" depends on HAVE_SYSCALL_TRACEPOINTS select GENERIC_TRACER select KALLSYMS help Basic tracer to catch the syscall entry and exit events.

config TRACER_SNAPSHOT bool "Create a snapshot trace buffer" select TRACER_MAX_TRACE help Allow tracing users to take snapshot of the current buffer using the ftrace interface, e.g.:

      echo 1 > /sys/kernel/debug/tracing/snapshot
      cat snapshot

config TRACE_BRANCH_PROFILING bool select GENERIC_TRACER

choice prompt "Branch Profiling" default BRANCH_PROFILE_NONE help The branch profiling is a software profiler. It will add hooks into the C conditionals to test which path a branch takes.

 The likely/unlikely profiler only looks at the conditions that
 are annotated with a likely or unlikely macro.

 The "all branch" profiler will profile every if-statement in the
 kernel. This profiler will also enable the likely/unlikely
 profiler.

 Either of the above profilers adds a bit of overhead to the system.
 If unsure, choose "No branch profiling".

config BRANCH_PROFILE_NONE bool "No branch profiling" help No branch profiling. Branch profiling adds a bit of overhead. Only enable it if you want to analyse the branching behavior. Otherwise keep it disabled.

config PROFILE_ANNOTATED_BRANCHES bool "Trace likely/unlikely profiler" select TRACE_BRANCH_PROFILING help This tracer profiles all likely and unlikely macros in the kernel. It will display the results in:

  /sys/kernel/debug/tracing/trace_stat/branch_annotated

  Note: this will add a significant overhead; only turn this
  on if you need to profile the system's use of these macros.

config PROFILE_ALL_BRANCHES bool "Profile all if conditionals" select 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:

  /sys/kernel/debug/tracing/trace_stat/branch_all

  This option also enables the likely/unlikely profiler.

  This configuration, when enabled, will impose a great overhead
  on the system. This should only be enabled when the system
  is to be analyzed in much detail.

endchoice

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 STACK_TRACER bool "Trace max stack" depends on HAVE_FUNCTION_TRACER select FUNCTION_TRACER select STACKTRACE select KALLSYMS help This special tracer records the maximum stack footprint of the kernel and displays it in /sys/kernel/debug/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 BLK_DEV_IO_TRACE bool "Support for tracing block IO actions" depends on SYSFS depends on BLOCK select RELAY select DEBUG_FS select TRACEPOINTS select GENERIC_TRACER select STACKTRACE help Say Y here if you want to be able to trace the block layer actions on a given queue. Tracing allows you to see any traffic happening on a block device queue. For more information (and the userspace support tools needed), fetch the blktrace tools from:

  git://git.kernel.dk/blktrace.git

  Tracing also is possible using the ftrace interface, e.g.:

    echo 1 > /sys/block/sda/sda1/trace/enable
    echo blk > /sys/kernel/debug/tracing/current_tracer
    cat /sys/kernel/debug/tracing/trace_pipe

  If unsure, say N.

config KPROBE_EVENT depends on KPROBES depends on HAVE_REGS_AND_STACK_ACCESS_API bool "Enable kprobes-based dynamic events" select TRACING select PROBE_EVENTS default y help This allows the user to add tracing events (similar to tracepoints) on the fly via the ftrace interface. See Documentation/trace/kprobetrace.txt for more details.

  Those events can be inserted wherever kprobes can probe, and record
  various register and memory values.

  This option is also required by perf-probe subcommand of perf tools.
  If you want to use perf tools, this option is strongly recommended.

config UPROBE_EVENT bool "Enable uprobes-based dynamic events" depends on ARCH_SUPPORTS_UPROBES depends on MMU select UPROBES select PROBE_EVENTS select TRACING default n help This allows the user to add tracing events on top of userspace dynamic events (similar to tracepoints) on the fly via the trace events interface. Those events can be inserted wherever uprobes can probe, and record various registers. This option is required if you plan to use perf-probe subcommand of perf tools on user space applications.

config PROBE_EVENTS def_bool n

config DYNAMIC_FTRACE bool "enable/disable ftrace tracepoints dynamically" depends on FUNCTION_TRACER depends on HAVE_DYNAMIC_FTRACE default y help This option will modify all the calls to ftrace dynamically (will patch them out of the binary image and replace 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 DYNAMIC_FTRACE_WITH_REGS def_bool y depends on DYNAMIC_FTRACE depends on HAVE_DYNAMIC_FTRACE_WITH_REGS

config FUNCTION_PROFILER bool "Kernel function profiler" depends on FUNCTION_TRACER default n help This option enables the kernel function profiler. A file is created in debugfs called function_profile_enabled which defaults to zero. When a 1 is echoed into this file profiling begins, and when a zero is entered, profiling stops. A "functions" file is created in the trace_stats directory; this file shows the list of functions that have been hit and their counters.

  If in doubt, say N.

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 GENERIC_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 EVENT_TRACE_TEST_SYSCALLS bool "Run selftest on syscall events" depends on FTRACE_STARTUP_TEST help This option will also enable testing every syscall event. It only enables the event and disables it and runs various loads with the event enabled. This adds a bit more time for kernel boot up since it runs this on every system call defined.

 TBD - enable a way to actually call the syscalls as we test their
       events

config MMIOTRACE bool "Memory mapped IO tracing" depends on HAVE_MMIOTRACE_SUPPORT && PCI select GENERIC_TRACER 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/trace/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.

config RING_BUFFER_BENCHMARK tristate "Ring buffer benchmark stress tester" depends on RING_BUFFER help This option creates a test to stress the ring buffer and benchmark it. It creates its own ring buffer such that it will not interfere with any other users of the ring buffer (such as ftrace). It then creates a producer and consumer that will run for 10 seconds and sleep for 10 seconds. Each interval it will print out the number of events it recorded and give a rough estimate of how long each iteration took.

  It does not disable interrupts or raise its priority, so it may be
  affected by processes that are running.

  If unsure, say N.

endif # FTRACE

endif # TRACING_SUPPORT