kernel/trace/Kconfig

   1 #
   2 # Architectures that offer an FUNCTION_TRACER implementation should
   3 #  select HAVE_FUNCTION_TRACER:
   4 #
   5
   6 config USER_STACKTRACE_SUPPORT
   7         bool
   8
   9 config NOP_TRACER
  10         bool
  11
  12 config HAVE_FUNCTION_TRACER
  13         bool
  14
  15 config HAVE_FUNCTION_RET_TRACER
  16         bool
  17
  18 config HAVE_FUNCTION_TRACE_MCOUNT_TEST
  19         bool
  20         help
  21          This gets selected when the arch tests the function_trace_stop
  22          variable at the mcount call site. Otherwise, this variable
  23          is tested by the called function.
  24
  25 config HAVE_DYNAMIC_FTRACE
  26         bool
  27
  28 config HAVE_FTRACE_MCOUNT_RECORD
  29         bool
  30
  31 config TRACER_MAX_TRACE
  32         bool
  33
  34 config RING_BUFFER
  35         bool
  36
  37 config TRACING
  38         bool
  39         select DEBUG_FS
  40         select RING_BUFFER
  41         select STACKTRACE if STACKTRACE_SUPPORT
  42         select TRACEPOINTS
  43         select NOP_TRACER
  44
  45 menu "Tracers"
  46
  47 config FUNCTION_TRACER
  48         bool "Kernel Function Tracer"
  49         depends on HAVE_FUNCTION_TRACER
  50         depends on DEBUG_KERNEL
  51         select FRAME_POINTER
  52         select TRACING
  53         select CONTEXT_SWITCH_TRACER
  54         help
  55           Enable the kernel to trace every kernel function. This is done
  56           by using a compiler feature to insert a small, 5-byte No-Operation
  57           instruction to the beginning of every kernel function, which NOP
  58           sequence is then dynamically patched into a tracer call when
  59           tracing is enabled by the administrator. If it's runtime disabled
  60           (the bootup default), then the overhead of the instructions is very
  61           small and not measurable even in micro-benchmarks.
  62
  63 config FUNCTION_RET_TRACER
  64         bool "Kernel Function return Tracer"
  65         depends on HAVE_FUNCTION_RET_TRACER
  66         depends on FUNCTION_TRACER
  67         help
  68           Enable the kernel to trace a function at its return.
  69           It's first purpose is to trace the duration of functions.
  70           This is done by setting the current return address on the thread
  71           info structure of the current task.
  72
  73 config IRQSOFF_TRACER
  74         bool "Interrupts-off Latency Tracer"
  75         default n
  76         depends on TRACE_IRQFLAGS_SUPPORT
  77         depends on GENERIC_TIME
  78         depends on DEBUG_KERNEL
  79         select TRACE_IRQFLAGS
  80         select TRACING
  81         select TRACER_MAX_TRACE
  82         help
  83           This option measures the time spent in irqs-off critical
  84           sections, with microsecond accuracy.
  85
  86           The default measurement method is a maximum search, which is
  87           disabled by default and can be runtime (re-)started
  88           via:
  89
  90               echo 0 > /debugfs/tracing/tracing_max_latency
  91
  92           (Note that kernel size and overhead increases with this option
  93           enabled. This option and the preempt-off timing option can be
  94           used together or separately.)
  95
  96 config PREEMPT_TRACER
  97         bool "Preemption-off Latency Tracer"
  98         default n
  99         depends on GENERIC_TIME
 100         depends on PREEMPT
 101         depends on DEBUG_KERNEL
 102         select TRACING
 103         select TRACER_MAX_TRACE
 104         help
 105           This option measures the time spent in preemption off critical
 106           sections, with microsecond accuracy.
 107
 108           The default measurement method is a maximum search, which is
 109           disabled by default and can be runtime (re-)started
 110           via:
 111
 112               echo 0 > /debugfs/tracing/tracing_max_latency
 113
 114           (Note that kernel size and overhead increases with this option
 115           enabled. This option and the irqs-off timing option can be
 116           used together or separately.)
 117
 118 config SYSPROF_TRACER
 119         bool "Sysprof Tracer"
 120         depends on X86
 121         select TRACING
 122         help
 123           This tracer provides the trace needed by the 'Sysprof' userspace
 124           tool.
 125
 126 config SCHED_TRACER
 127         bool "Scheduling Latency Tracer"
 128         depends on DEBUG_KERNEL
 129         select TRACING
 130         select CONTEXT_SWITCH_TRACER
 131         select TRACER_MAX_TRACE
 132         help
 133           This tracer tracks the latency of the highest priority task
 134           to be scheduled in, starting from the point it has woken up.
 135
 136 config CONTEXT_SWITCH_TRACER
 137         bool "Trace process context switches"
 138         depends on DEBUG_KERNEL
 139         select TRACING
 140         select MARKERS
 141         help
 142           This tracer gets called from the context switch and records
 143           all switching of tasks.
 144
 145 config BOOT_TRACER
 146         bool "Trace boot initcalls"
 147         depends on DEBUG_KERNEL
 148         select TRACING
 149         select CONTEXT_SWITCH_TRACER
 150         help
 151           This tracer helps developers to optimize boot times: it records
 152           the timings of the initcalls and traces key events and the identity
 153           of tasks that can cause boot delays, such as context-switches.
 154
 155           Its aim is to be parsed by the /scripts/bootgraph.pl tool to
 156           produce pretty graphics about boot inefficiencies, giving a visual
 157           representation of the delays during initcalls - but the raw
 158           /debug/tracing/trace text output is readable too.
 159
 160           ( Note that tracing self tests can't be enabled if this tracer is
 161             selected, because the self-tests are an initcall as well and that
 162             would invalidate the boot trace. )
 163
 164 config TRACE_BRANCH_PROFILING
 165         bool "Trace likely/unlikely profiler"
 166         depends on DEBUG_KERNEL
 167         select TRACING
 168         help
 169           This tracer profiles all the the likely and unlikely macros
 170           in the kernel. It will display the results in:
 171
 172           /debugfs/tracing/profile_likely
 173           /debugfs/tracing/profile_unlikely
 174
 175           Note: this will add a significant overhead, only turn this
 176           on if you need to profile the system's use of these macros.
 177
 178           Say N if unsure.
 179
 180 config TRACING_BRANCHES
 181         bool
 182         help
 183           Selected by tracers that will trace the likely and unlikely
 184           conditions. This prevents the tracers themselves from being
 185           profiled. Profiling the tracing infrastructure can only happen
 186           when the likelys and unlikelys are not being traced.
 187
 188 config BRANCH_TRACER
 189         bool "Trace likely/unlikely instances"
 190         depends on TRACE_BRANCH_PROFILING
 191         select TRACING_BRANCHES
 192         help
 193           This traces the events of likely and unlikely condition
 194           calls in the kernel.  The difference between this and the
 195           "Trace likely/unlikely profiler" is that this is not a
 196           histogram of the callers, but actually places the calling
 197           events into a running trace buffer to see when and where the
 198           events happened, as well as their results.
 199
 200           Say N if unsure.
 201
 202 config STACK_TRACER
 203         bool "Trace max stack"
 204         depends on HAVE_FUNCTION_TRACER
 205         depends on DEBUG_KERNEL
 206         select FUNCTION_TRACER
 207         select STACKTRACE
 208         help
 209           This special tracer records the maximum stack footprint of the
 210           kernel and displays it in debugfs/tracing/stack_trace.
 211
 212           This tracer works by hooking into every function call that the
 213           kernel executes, and keeping a maximum stack depth value and
 214           stack-trace saved. Because this logic has to execute in every
 215           kernel function, all the time, this option can slow down the
 216           kernel measurably and is generally intended for kernel
 217           developers only.
 218
 219           Say N if unsure.
 220
 221 config DYNAMIC_FTRACE
 222         bool "enable/disable ftrace tracepoints dynamically"
 223         depends on FUNCTION_TRACER
 224         depends on HAVE_DYNAMIC_FTRACE
 225         depends on DEBUG_KERNEL
 226         default y
 227         help
 228          This option will modify all the calls to ftrace dynamically
 229          (will patch them out of the binary image and replaces them
 230          with a No-Op instruction) as they are called. A table is
 231          created to dynamically enable them again.
 232
 233          This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but otherwise
 234          has native performance as long as no tracing is active.
 235
 236          The changes to the code are done by a kernel thread that
 237          wakes up once a second and checks to see if any ftrace calls
 238          were made. If so, it runs stop_machine (stops all CPUS)
 239          and modifies the code to jump over the call to ftrace.
 240
 241 config FTRACE_MCOUNT_RECORD
 242         def_bool y
 243         depends on DYNAMIC_FTRACE
 244         depends on HAVE_FTRACE_MCOUNT_RECORD
 245
 246 config FTRACE_SELFTEST
 247         bool
 248
 249 config FTRACE_STARTUP_TEST
 250         bool "Perform a startup test on ftrace"
 251         depends on TRACING && DEBUG_KERNEL && !BOOT_TRACER
 252         select FTRACE_SELFTEST
 253         help
 254           This option performs a series of startup tests on ftrace. On bootup
 255           a series of tests are made to verify that the tracer is
 256           functioning properly. It will do tests on all the configured
 257           tracers of ftrace.
 258
 259 endmenu