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