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
  12 config HAVE_DYNAMIC_FTRACE
  13         bool
  14
  15 config HAVE_FTRACE_MCOUNT_RECORD
  16         bool
  17
  18 config TRACER_MAX_TRACE
  19         bool
  20
  21 config RING_BUFFER
  22         bool
  23
  24 config TRACING
  25         bool
  26         select DEBUG_FS
  27         select RING_BUFFER
  28         select STACKTRACE if STACKTRACE_SUPPORT
  29         select TRACEPOINTS
  30         select NOP_TRACER
  31
  32 menu "Tracers"
  33
  34 config FUNCTION_TRACER
  35         bool "Kernel Function Tracer"
  36         depends on HAVE_FUNCTION_TRACER
  37         depends on DEBUG_KERNEL
  38         select FRAME_POINTER
  39         select TRACING
  40         select CONTEXT_SWITCH_TRACER
  41         help
  42           Enable the kernel to trace every kernel function. This is done
  43           by using a compiler feature to insert a small, 5-byte No-Operation
  44           instruction to the beginning of every kernel function, which NOP
  45           sequence is then dynamically patched into a tracer call when
  46           tracing is enabled by the administrator. If it's runtime disabled
  47           (the bootup default), then the overhead of the instructions is very
  48           small and not measurable even in micro-benchmarks.
  49
  50 config IRQSOFF_TRACER
  51         bool "Interrupts-off Latency Tracer"
  52         default n
  53         depends on TRACE_IRQFLAGS_SUPPORT
  54         depends on GENERIC_TIME
  55         depends on DEBUG_KERNEL
  56         select TRACE_IRQFLAGS
  57         select TRACING
  58         select TRACER_MAX_TRACE
  59         help
  60           This option measures the time spent in irqs-off critical
  61           sections, with microsecond accuracy.
  62
  63           The default measurement method is a maximum search, which is
  64           disabled by default and can be runtime (re-)started
  65           via:
  66
  67               echo 0 > /debugfs/tracing/tracing_max_latency
  68
  69           (Note that kernel size and overhead increases with this option
  70           enabled. This option and the preempt-off timing option can be
  71           used together or separately.)
  72
  73 config PREEMPT_TRACER
  74         bool "Preemption-off Latency Tracer"
  75         default n
  76         depends on GENERIC_TIME
  77         depends on PREEMPT
  78         depends on DEBUG_KERNEL
  79         select TRACING
  80         select TRACER_MAX_TRACE
  81         help
  82           This option measures the time spent in preemption off critical
  83           sections, with microsecond accuracy.
  84
  85           The default measurement method is a maximum search, which is
  86           disabled by default and can be runtime (re-)started
  87           via:
  88
  89               echo 0 > /debugfs/tracing/tracing_max_latency
  90
  91           (Note that kernel size and overhead increases with this option
  92           enabled. This option and the irqs-off timing option can be
  93           used together or separately.)
  94
  95 config SYSPROF_TRACER
  96         bool "Sysprof Tracer"
  97         depends on X86
  98         select TRACING
  99         help
 100           This tracer provides the trace needed by the 'Sysprof' userspace
 101           tool.
 102
 103 config SCHED_TRACER
 104         bool "Scheduling Latency Tracer"
 105         depends on DEBUG_KERNEL
 106         select TRACING
 107         select CONTEXT_SWITCH_TRACER
 108         select TRACER_MAX_TRACE
 109         help
 110           This tracer tracks the latency of the highest priority task
 111           to be scheduled in, starting from the point it has woken up.
 112
 113 config CONTEXT_SWITCH_TRACER
 114         bool "Trace process context switches"
 115         depends on DEBUG_KERNEL
 116         select TRACING
 117         select MARKERS
 118         help
 119           This tracer gets called from the context switch and records
 120           all switching of tasks.
 121
 122 config BOOT_TRACER
 123         bool "Trace boot initcalls"
 124         depends on DEBUG_KERNEL
 125         select TRACING
 126         select CONTEXT_SWITCH_TRACER
 127         help
 128           This tracer helps developers to optimize boot times: it records
 129           the timings of the initcalls and traces key events and the identity
 130           of tasks that can cause boot delays, such as context-switches.
 131
 132           Its aim is to be parsed by the /scripts/bootgraph.pl tool to
 133           produce pretty graphics about boot inefficiencies, giving a visual
 134           representation of the delays during initcalls - but the raw
 135           /debug/tracing/trace text output is readable too.
 136
 137           ( Note that tracing self tests can't be enabled if this tracer is
 138             selected, because the self-tests are an initcall as well and that
 139             would invalidate the boot trace. )
 140
 141 config STACK_TRACER
 142         bool "Trace max stack"
 143         depends on HAVE_FUNCTION_TRACER
 144         depends on DEBUG_KERNEL
 145         select FUNCTION_TRACER
 146         select STACKTRACE
 147         help
 148           This special tracer records the maximum stack footprint of the
 149           kernel and displays it in debugfs/tracing/stack_trace.
 150
 151           This tracer works by hooking into every function call that the
 152           kernel executes, and keeping a maximum stack depth value and
 153           stack-trace saved. Because this logic has to execute in every
 154           kernel function, all the time, this option can slow down the
 155           kernel measurably and is generally intended for kernel
 156           developers only.
 157
 158           Say N if unsure.
 159
 160 config DYNAMIC_FTRACE
 161         bool "enable/disable ftrace tracepoints dynamically"
 162         depends on FUNCTION_TRACER
 163         depends on HAVE_DYNAMIC_FTRACE
 164         depends on DEBUG_KERNEL
 165         default y
 166         help
 167          This option will modify all the calls to ftrace dynamically
 168          (will patch them out of the binary image and replaces them
 169          with a No-Op instruction) as they are called. A table is
 170          created to dynamically enable them again.
 171
 172          This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but otherwise
 173          has native performance as long as no tracing is active.
 174
 175          The changes to the code are done by a kernel thread that
 176          wakes up once a second and checks to see if any ftrace calls
 177          were made. If so, it runs stop_machine (stops all CPUS)
 178          and modifies the code to jump over the call to ftrace.
 179
 180 config FTRACE_MCOUNT_RECORD
 181         def_bool y
 182         depends on DYNAMIC_FTRACE
 183         depends on HAVE_FTRACE_MCOUNT_RECORD
 184
 185 config FTRACE_SELFTEST
 186         bool
 187
 188 config FTRACE_STARTUP_TEST
 189         bool "Perform a startup test on ftrace"
 190         depends on TRACING && DEBUG_KERNEL && !BOOT_TRACER
 191         select FTRACE_SELFTEST
 192         help
 193           This option performs a series of startup tests on ftrace. On bootup
 194           a series of tests are made to verify that the tracer is
 195           functioning properly. It will do tests on all the configured
 196           tracers of ftrace.
 197
 198 endmenu