kernel/trace/Kconfig

   1 #
   2 # Architectures that offer an FUNCTION_TRACER implementation should
   3 #  select HAVE_FUNCTION_TRACER:
   4 #
   5
   6 config NOP_TRACER
   7         bool
   8
   9 config HAVE_FUNCTION_TRACER
  10         bool
  11         select NOP_TRACER
  12
  13 config HAVE_DYNAMIC_FTRACE
  14         bool
  15
  16 config HAVE_FTRACE_MCOUNT_RECORD
  17         bool
  18
  19 config TRACER_MAX_TRACE
  20         bool
  21
  22 config RING_BUFFER
  23         bool
  24
  25 config TRACING
  26         bool
  27         select DEBUG_FS
  28         select RING_BUFFER
  29         select STACKTRACE
  30         select TRACEPOINTS
  31
  32 config FUNCTION_TRACER
  33         bool "Kernel Function Tracer"
  34         depends on HAVE_FUNCTION_TRACER
  35         depends on DEBUG_KERNEL
  36         select FRAME_POINTER
  37         select TRACING
  38         select CONTEXT_SWITCH_TRACER
  39         help
  40           Enable the kernel to trace every kernel function. This is done
  41           by using a compiler feature to insert a small, 5-byte No-Operation
  42           instruction to the beginning of every kernel function, which NOP
  43           sequence is then dynamically patched into a tracer call when
  44           tracing is enabled by the administrator. If it's runtime disabled
  45           (the bootup default), then the overhead of the instructions is very
  46           small and not measurable even in micro-benchmarks.
  47
  48 config IRQSOFF_TRACER
  49         bool "Interrupts-off Latency Tracer"
  50         default n
  51         depends on TRACE_IRQFLAGS_SUPPORT
  52         depends on GENERIC_TIME
  53         depends on DEBUG_KERNEL
  54         select TRACE_IRQFLAGS
  55         select TRACING
  56         select TRACER_MAX_TRACE
  57         help
  58           This option measures the time spent in irqs-off critical
  59           sections, with microsecond accuracy.
  60
  61           The default measurement method is a maximum search, which is
  62           disabled by default and can be runtime (re-)started
  63           via:
  64
  65               echo 0 > /debugfs/tracing/tracing_max_latency
  66
  67           (Note that kernel size and overhead increases with this option
  68           enabled. This option and the preempt-off timing option can be
  69           used together or separately.)
  70
  71 config PREEMPT_TRACER
  72         bool "Preemption-off Latency Tracer"
  73         default n
  74         depends on GENERIC_TIME
  75         depends on PREEMPT
  76         depends on DEBUG_KERNEL
  77         select TRACING
  78         select TRACER_MAX_TRACE
  79         help
  80           This option measures the time spent in preemption off critical
  81           sections, with microsecond accuracy.
  82
  83           The default measurement method is a maximum search, which is
  84           disabled by default and can be runtime (re-)started
  85           via:
  86
  87               echo 0 > /debugfs/tracing/tracing_max_latency
  88
  89           (Note that kernel size and overhead increases with this option
  90           enabled. This option and the irqs-off timing option can be
  91           used together or separately.)
  92
  93 config SYSPROF_TRACER
  94         bool "Sysprof Tracer"
  95         depends on X86
  96         select TRACING
  97         help
  98           This tracer provides the trace needed by the 'Sysprof' userspace
  99           tool.
 100
 101 config SCHED_TRACER
 102         bool "Scheduling Latency Tracer"
 103         depends on DEBUG_KERNEL
 104         select TRACING
 105         select CONTEXT_SWITCH_TRACER
 106         select TRACER_MAX_TRACE
 107         help
 108           This tracer tracks the latency of the highest priority task
 109           to be scheduled in, starting from the point it has woken up.
 110
 111 config CONTEXT_SWITCH_TRACER
 112         bool "Trace process context switches"
 113         depends on DEBUG_KERNEL
 114         select TRACING
 115         select MARKERS
 116         help
 117           This tracer gets called from the context switch and records
 118           all switching of tasks.
 119
 120 config BOOT_TRACER
 121         bool "Trace boot initcalls"
 122         depends on DEBUG_KERNEL
 123         select TRACING
 124         help
 125           This tracer helps developers to optimize boot times: it records
 126           the timings of the initcalls and traces key events and the identity
 127           of tasks that can cause boot delays, such as context-switches.
 128
 129           Its aim is to be parsed by the /scripts/bootgraph.pl tool to
 130           produce pretty graphics about boot inefficiencies, giving a visual
 131           representation of the delays during initcalls - but the raw
 132           /debug/tracing/trace text output is readable too.
 133
 134           ( Note that tracing self tests can't be enabled if this tracer is
 135             selected, because the self-tests are an initcall as well and that
 136             would invalidate the boot trace. )
 137
 138 config STACK_TRACER
 139         bool "Trace max stack"
 140         depends on HAVE_FUNCTION_TRACER
 141         depends on DEBUG_KERNEL
 142         select FUNCTION_TRACER
 143         select STACKTRACE
 144         help
 145           This special tracer records the maximum stack footprint of the
 146           kernel and displays it in debugfs/tracing/stack_trace.
 147
 148           This tracer works by hooking into every function call that the
 149           kernel executes, and keeping a maximum stack depth value and
 150           stack-trace saved. Because this logic has to execute in every
 151           kernel function, all the time, this option can slow down the
 152           kernel measurably and is generally intended for kernel
 153           developers only.
 154
 155           Say N if unsure.
 156
 157 config DYNAMIC_FTRACE
 158         bool "enable/disable ftrace tracepoints dynamically"
 159         depends on FUNCTION_TRACER
 160         depends on HAVE_DYNAMIC_FTRACE
 161         depends on DEBUG_KERNEL
 162         default y
 163         help
 164          This option will modify all the calls to ftrace dynamically
 165          (will patch them out of the binary image and replaces them
 166          with a No-Op instruction) as they are called. A table is
 167          created to dynamically enable them again.
 168
 169          This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but otherwise
 170          has native performance as long as no tracing is active.
 171
 172          The changes to the code are done by a kernel thread that
 173          wakes up once a second and checks to see if any ftrace calls
 174          were made. If so, it runs stop_machine (stops all CPUS)
 175          and modifies the code to jump over the call to ftrace.
 176
 177 config FTRACE_MCOUNT_RECORD
 178         def_bool y
 179         depends on DYNAMIC_FTRACE
 180         depends on HAVE_FTRACE_MCOUNT_RECORD
 181
 182 config FTRACE_SELFTEST
 183         bool
 184
 185 config FTRACE_STARTUP_TEST
 186         bool "Perform a startup test on ftrace"
 187         depends on TRACING && DEBUG_KERNEL && !BOOT_TRACER
 188         select FTRACE_SELFTEST
 189         help
 190           This option performs a series of startup tests on ftrace. On bootup
 191           a series of tests are made to verify that the tracer is
 192           functioning properly. It will do tests on all the configured
 193           tracers of ftrace.