kernel/trace/Kconfig

   1 #
   2 # Architectures that offer an FTRACE implementation should select HAVE_FTRACE:
   3 #
   4 config HAVE_FTRACE
   5         bool
   6
   7 config HAVE_DYNAMIC_FTRACE
   8         bool
   9
  10 config TRACER_MAX_TRACE
  11         bool
  12
  13 config TRACING
  14         bool
  15         select DEBUG_FS
  16         select STACKTRACE
  17
  18 config FTRACE
  19         bool "Kernel Function Tracer"
  20         depends on HAVE_FTRACE
  21         select FRAME_POINTER
  22         select TRACING
  23         select CONTEXT_SWITCH_TRACER
  24         help
  25           Enable the kernel to trace every kernel function. This is done
  26           by using a compiler feature to insert a small, 5-byte No-Operation
  27           instruction to the beginning of every kernel function, which NOP
  28           sequence is then dynamically patched into a tracer call when
  29           tracing is enabled by the administrator. If it's runtime disabled
  30           (the bootup default), then the overhead of the instructions is very
  31           small and not measurable even in micro-benchmarks.
  32
  33 config IRQSOFF_TRACER
  34         bool "Interrupts-off Latency Tracer"
  35         default n
  36         depends on TRACE_IRQFLAGS_SUPPORT
  37         depends on GENERIC_TIME
  38         depends on HAVE_FTRACE
  39         select TRACE_IRQFLAGS
  40         select TRACING
  41         select TRACER_MAX_TRACE
  42         help
  43           This option measures the time spent in irqs-off critical
  44           sections, with microsecond accuracy.
  45
  46           The default measurement method is a maximum search, which is
  47           disabled by default and can be runtime (re-)started
  48           via:
  49
  50               echo 0 > /debugfs/tracing/tracing_max_latency
  51
  52           (Note that kernel size and overhead increases with this option
  53           enabled. This option and the preempt-off timing option can be
  54           used together or separately.)
  55
  56 config PREEMPT_TRACER
  57         bool "Preemption-off Latency Tracer"
  58         default n
  59         depends on GENERIC_TIME
  60         depends on PREEMPT
  61         depends on HAVE_FTRACE
  62         select TRACING
  63         select TRACER_MAX_TRACE
  64         help
  65           This option measures the time spent in preemption off critical
  66           sections, with microsecond accuracy.
  67
  68           The default measurement method is a maximum search, which is
  69           disabled by default and can be runtime (re-)started
  70           via:
  71
  72               echo 0 > /debugfs/tracing/tracing_max_latency
  73
  74           (Note that kernel size and overhead increases with this option
  75           enabled. This option and the irqs-off timing option can be
  76           used together or separately.)
  77
  78 config SCHED_TRACER
  79         bool "Scheduling Latency Tracer"
  80         depends on HAVE_FTRACE
  81         select TRACING
  82         select CONTEXT_SWITCH_TRACER
  83         select TRACER_MAX_TRACE
  84         help
  85           This tracer tracks the latency of the highest priority task
  86           to be scheduled in, starting from the point it has woken up.
  87
  88 config CONTEXT_SWITCH_TRACER
  89         bool "Trace process context switches"
  90         depends on HAVE_FTRACE
  91         select TRACING
  92         select MARKERS
  93         help
  94           This tracer gets called from the context switch and records
  95           all switching of tasks.
  96
  97 config DYNAMIC_FTRACE
  98         bool "enable/disable ftrace tracepoints dynamically"
  99         depends on FTRACE
 100         depends on HAVE_DYNAMIC_FTRACE
 101         default y
 102         help
 103          This option will modify all the calls to ftrace dynamically
 104          (will patch them out of the binary image and replaces them
 105          with a No-Op instruction) as they are called. A table is
 106          created to dynamically enable them again.
 107
 108          This way a CONFIG_FTRACE kernel is slightly larger, but otherwise
 109          has native performance as long as no tracing is active.
 110
 111          The changes to the code are done by a kernel thread that
 112          wakes up once a second and checks to see if any ftrace calls
 113          were made. If so, it runs stop_machine (stops all CPUS)
 114          and modifies the code to jump over the call to ftrace.
 115
 116 config FTRACE_SELFTEST
 117         bool
 118
 119 config FTRACE_STARTUP_TEST
 120         bool "Perform a startup test on ftrace"
 121         depends on TRACING
 122         select FTRACE_SELFTEST
 123         help
 124           This option performs a series of startup tests on ftrace. On bootup
 125           a series of tests are made to verify that the tracer is
 126           functioning properly. It will do tests on all the configured
 127           tracers of ftrace.