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_GRAPH_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 HAVE_HW_BRANCH_TRACER
  32         bool
  33
  34 config TRACER_MAX_TRACE
  35         bool
  36
  37 config RING_BUFFER
  38         bool
  39
  40 config TRACING
  41         bool
  42         select DEBUG_FS
  43         select RING_BUFFER
  44         select STACKTRACE if STACKTRACE_SUPPORT
  45         select TRACEPOINTS
  46         select NOP_TRACER
  47
  48 menu "Tracers"
  49
  50 config FUNCTION_TRACER
  51         bool "Kernel Function Tracer"
  52         depends on HAVE_FUNCTION_TRACER
  53         depends on DEBUG_KERNEL
  54         select FRAME_POINTER
  55         select TRACING
  56         select CONTEXT_SWITCH_TRACER
  57         help
  58           Enable the kernel to trace every kernel function. This is done
  59           by using a compiler feature to insert a small, 5-byte No-Operation
  60           instruction to the beginning of every kernel function, which NOP
  61           sequence is then dynamically patched into a tracer call when
  62           tracing is enabled by the administrator. If it's runtime disabled
  63           (the bootup default), then the overhead of the instructions is very
  64           small and not measurable even in micro-benchmarks.
  65
  66 config FUNCTION_GRAPH_TRACER
  67         bool "Kernel Function Graph Tracer"
  68         depends on HAVE_FUNCTION_GRAPH_TRACER
  69         depends on FUNCTION_TRACER
  70         default y
  71         help
  72           Enable the kernel to trace a function at both its return
  73           and its entry.
  74           It's first purpose is to trace the duration of functions and
  75           draw a call graph for each thread with some informations like
  76           the return value.
  77           This is done by setting the current return address on the current
  78           task structure into a stack of calls.
  79
  80 config IRQSOFF_TRACER
  81         bool "Interrupts-off Latency Tracer"
  82         default n
  83         depends on TRACE_IRQFLAGS_SUPPORT
  84         depends on GENERIC_TIME
  85         depends on DEBUG_KERNEL
  86         select TRACE_IRQFLAGS
  87         select TRACING
  88         select TRACER_MAX_TRACE
  89         help
  90           This option measures the time spent in irqs-off critical
  91           sections, with microsecond accuracy.
  92
  93           The default measurement method is a maximum search, which is
  94           disabled by default and can be runtime (re-)started
  95           via:
  96
  97               echo 0 > /debugfs/tracing/tracing_max_latency
  98
  99           (Note that kernel size and overhead increases with this option
 100           enabled. This option and the preempt-off timing option can be
 101           used together or separately.)
 102
 103 config PREEMPT_TRACER
 104         bool "Preemption-off Latency Tracer"
 105         default n
 106         depends on GENERIC_TIME
 107         depends on PREEMPT
 108         depends on DEBUG_KERNEL
 109         select TRACING
 110         select TRACER_MAX_TRACE
 111         help
 112           This option measures the time spent in preemption off critical
 113           sections, with microsecond accuracy.
 114
 115           The default measurement method is a maximum search, which is
 116           disabled by default and can be runtime (re-)started
 117           via:
 118
 119               echo 0 > /debugfs/tracing/tracing_max_latency
 120
 121           (Note that kernel size and overhead increases with this option
 122           enabled. This option and the irqs-off timing option can be
 123           used together or separately.)
 124
 125 config SYSPROF_TRACER
 126         bool "Sysprof Tracer"
 127         depends on X86
 128         select TRACING
 129         help
 130           This tracer provides the trace needed by the 'Sysprof' userspace
 131           tool.
 132
 133 config SCHED_TRACER
 134         bool "Scheduling Latency Tracer"
 135         depends on DEBUG_KERNEL
 136         select TRACING
 137         select CONTEXT_SWITCH_TRACER
 138         select TRACER_MAX_TRACE
 139         help
 140           This tracer tracks the latency of the highest priority task
 141           to be scheduled in, starting from the point it has woken up.
 142
 143 config CONTEXT_SWITCH_TRACER
 144         bool "Trace process context switches"
 145         depends on DEBUG_KERNEL
 146         select TRACING
 147         select MARKERS
 148         help
 149           This tracer gets called from the context switch and records
 150           all switching of tasks.
 151
 152 config BOOT_TRACER
 153         bool "Trace boot initcalls"
 154         depends on DEBUG_KERNEL
 155         select TRACING
 156         select CONTEXT_SWITCH_TRACER
 157         help
 158           This tracer helps developers to optimize boot times: it records
 159           the timings of the initcalls and traces key events and the identity
 160           of tasks that can cause boot delays, such as context-switches.
 161
 162           Its aim is to be parsed by the /scripts/bootgraph.pl tool to
 163           produce pretty graphics about boot inefficiencies, giving a visual
 164           representation of the delays during initcalls - but the raw
 165           /debug/tracing/trace text output is readable too.
 166
 167           ( Note that tracing self tests can't be enabled if this tracer is
 168             selected, because the self-tests are an initcall as well and that
 169             would invalidate the boot trace. )
 170
 171 config TRACE_BRANCH_PROFILING
 172         bool "Trace likely/unlikely profiler"
 173         depends on DEBUG_KERNEL
 174         select TRACING
 175         help
 176           This tracer profiles all the the likely and unlikely macros
 177           in the kernel. It will display the results in:
 178
 179           /debugfs/tracing/profile_annotated_branch
 180
 181           Note: this will add a significant overhead, only turn this
 182           on if you need to profile the system's use of these macros.
 183
 184           Say N if unsure.
 185
 186 config PROFILE_ALL_BRANCHES
 187         bool "Profile all if conditionals"
 188         depends on TRACE_BRANCH_PROFILING
 189         help
 190           This tracer profiles all branch conditions. Every if ()
 191           taken in the kernel is recorded whether it hit or miss.
 192           The results will be displayed in:
 193
 194           /debugfs/tracing/profile_branch
 195
 196           This configuration, when enabled, will impose a great overhead
 197           on the system. This should only be enabled when the system
 198           is to be analyzed
 199
 200           Say N if unsure.
 201
 202 config TRACING_BRANCHES
 203         bool
 204         help
 205           Selected by tracers that will trace the likely and unlikely
 206           conditions. This prevents the tracers themselves from being
 207           profiled. Profiling the tracing infrastructure can only happen
 208           when the likelys and unlikelys are not being traced.
 209
 210 config BRANCH_TRACER
 211         bool "Trace likely/unlikely instances"
 212         depends on TRACE_BRANCH_PROFILING
 213         select TRACING_BRANCHES
 214         help
 215           This traces the events of likely and unlikely condition
 216           calls in the kernel.  The difference between this and the
 217           "Trace likely/unlikely profiler" is that this is not a
 218           histogram of the callers, but actually places the calling
 219           events into a running trace buffer to see when and where the
 220           events happened, as well as their results.
 221
 222           Say N if unsure.
 223
 224 config POWER_TRACER
 225         bool "Trace power consumption behavior"
 226         depends on DEBUG_KERNEL
 227         depends on X86
 228         select TRACING
 229         help
 230           This tracer helps developers to analyze and optimize the kernels
 231           power management decisions, specifically the C-state and P-state
 232           behavior.
 233
 234
 235 config STACK_TRACER
 236         bool "Trace max stack"
 237         depends on HAVE_FUNCTION_TRACER
 238         depends on DEBUG_KERNEL
 239         select FUNCTION_TRACER
 240         select STACKTRACE
 241         help
 242           This special tracer records the maximum stack footprint of the
 243           kernel and displays it in debugfs/tracing/stack_trace.
 244
 245           This tracer works by hooking into every function call that the
 246           kernel executes, and keeping a maximum stack depth value and
 247           stack-trace saved.  If this is configured with DYNAMIC_FTRACE
 248           then it will not have any overhead while the stack tracer
 249           is disabled.
 250
 251           To enable the stack tracer on bootup, pass in 'stacktrace'
 252           on the kernel command line.
 253
 254           The stack tracer can also be enabled or disabled via the
 255           sysctl kernel.stack_tracer_enabled
 256
 257           Say N if unsure.
 258
 259 config HW_BRANCH_TRACER
 260         depends on HAVE_HW_BRANCH_TRACER
 261         bool "Trace hw branches"
 262         select TRACING
 263         help
 264           This tracer records all branches on the system in a circular
 265           buffer giving access to the last N branches for each cpu.
 266
 267 config DYNAMIC_FTRACE
 268         bool "enable/disable ftrace tracepoints dynamically"
 269         depends on FUNCTION_TRACER
 270         depends on HAVE_DYNAMIC_FTRACE
 271         depends on DEBUG_KERNEL
 272         default y
 273         help
 274          This option will modify all the calls to ftrace dynamically
 275          (will patch them out of the binary image and replaces them
 276          with a No-Op instruction) as they are called. A table is
 277          created to dynamically enable them again.
 278
 279          This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but otherwise
 280          has native performance as long as no tracing is active.
 281
 282          The changes to the code are done by a kernel thread that
 283          wakes up once a second and checks to see if any ftrace calls
 284          were made. If so, it runs stop_machine (stops all CPUS)
 285          and modifies the code to jump over the call to ftrace.
 286
 287 config FTRACE_MCOUNT_RECORD
 288         def_bool y
 289         depends on DYNAMIC_FTRACE
 290         depends on HAVE_FTRACE_MCOUNT_RECORD
 291
 292 config FTRACE_SELFTEST
 293         bool
 294
 295 config FTRACE_STARTUP_TEST
 296         bool "Perform a startup test on ftrace"
 297         depends on TRACING && DEBUG_KERNEL && !BOOT_TRACER
 298         select FTRACE_SELFTEST
 299         help
 300           This option performs a series of startup tests on ftrace. On bootup
 301           a series of tests are made to verify that the tracer is
 302           functioning properly. It will do tests on all the configured
 303           tracers of ftrace.
 304
 305 endmenu