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_FTRACE_NMI_ENTER
  13         bool
  14         help
  15           See Documentation/trace/ftrace-design.txt
  16
  17 config HAVE_FUNCTION_TRACER
  18         bool
  19         help
  20           See Documentation/trace/ftrace-design.txt
  21
  22 config HAVE_FUNCTION_GRAPH_TRACER
  23         bool
  24         help
  25           See Documentation/trace/ftrace-design.txt
  26
  27 config HAVE_FUNCTION_GRAPH_FP_TEST
  28         bool
  29         help
  30           See Documentation/trace/ftrace-design.txt
  31
  32 config HAVE_FUNCTION_TRACE_MCOUNT_TEST
  33         bool
  34         help
  35           See Documentation/trace/ftrace-design.txt
  36
  37 config HAVE_DYNAMIC_FTRACE
  38         bool
  39         help
  40           See Documentation/trace/ftrace-design.txt
  41
  42 config HAVE_DYNAMIC_FTRACE_WITH_REGS
  43         bool
  44
  45 config HAVE_FTRACE_MCOUNT_RECORD
  46         bool
  47         help
  48           See Documentation/trace/ftrace-design.txt
  49
  50 config HAVE_SYSCALL_TRACEPOINTS
  51         bool
  52         help
  53           See Documentation/trace/ftrace-design.txt
  54
  55 config HAVE_FENTRY
  56         bool
  57         help
  58           Arch supports the gcc options -pg with -mfentry
  59
  60 config HAVE_C_RECORDMCOUNT
  61         bool
  62         help
  63           C version of recordmcount available?
  64
  65 config TRACER_MAX_TRACE
  66         bool
  67
  68 config TRACE_CLOCK
  69         bool
  70
  71 config RING_BUFFER
  72         bool
  73         select TRACE_CLOCK
  74         select IRQ_WORK
  75
  76 config FTRACE_NMI_ENTER
  77        bool
  78        depends on HAVE_FTRACE_NMI_ENTER
  79        default y
  80
  81 config EVENT_TRACING
  82         select CONTEXT_SWITCH_TRACER
  83         bool
  84
  85 config GPU_TRACEPOINTS
  86         bool
  87
  88 config CONTEXT_SWITCH_TRACER
  89         bool
  90
  91 config RING_BUFFER_ALLOW_SWAP
  92         bool
  93         help
  94          Allow the use of ring_buffer_swap_cpu.
  95          Adds a very slight overhead to tracing when enabled.
  96
  97 # All tracer options should select GENERIC_TRACER. For those options that are
  98 # enabled by all tracers (context switch and event tracer) they select TRACING.
  99 # This allows those options to appear when no other tracer is selected. But the
 100 # options do not appear when something else selects it. We need the two options
 101 # GENERIC_TRACER and TRACING to avoid circular dependencies to accomplish the
 102 # hiding of the automatic options.
 103
 104 config TRACING
 105         bool
 106         select DEBUG_FS
 107         select RING_BUFFER
 108         select STACKTRACE if STACKTRACE_SUPPORT
 109         select TRACEPOINTS
 110         select NOP_TRACER
 111         select BINARY_PRINTF
 112         select EVENT_TRACING
 113         select TRACE_CLOCK
 114
 115 config GENERIC_TRACER
 116         bool
 117         select TRACING
 118
 119 #
 120 # Minimum requirements an architecture has to meet for us to
 121 # be able to offer generic tracing facilities:
 122 #
 123 config TRACING_SUPPORT
 124         bool
 125         # PPC32 has no irqflags tracing support, but it can use most of the
 126         # tracers anyway, they were tested to build and work. Note that new
 127         # exceptions to this list aren't welcomed, better implement the
 128         # irqflags tracing for your architecture.
 129         depends on TRACE_IRQFLAGS_SUPPORT || PPC32
 130         depends on STACKTRACE_SUPPORT
 131         default y
 132
 133 if TRACING_SUPPORT
 134
 135 menuconfig FTRACE
 136         bool "Tracers"
 137         default y if DEBUG_KERNEL
 138         help
 139           Enable the kernel tracing infrastructure.
 140
 141 if FTRACE
 142
 143 config FUNCTION_TRACER
 144         bool "Kernel Function Tracer"
 145         depends on HAVE_FUNCTION_TRACER
 146         select KALLSYMS
 147         select GENERIC_TRACER
 148         select CONTEXT_SWITCH_TRACER
 149         help
 150           Enable the kernel to trace every kernel function. This is done
 151           by using a compiler feature to insert a small, 5-byte No-Operation
 152           instruction at the beginning of every kernel function, which NOP
 153           sequence is then dynamically patched into a tracer call when
 154           tracing is enabled by the administrator. If it's runtime disabled
 155           (the bootup default), then the overhead of the instructions is very
 156           small and not measurable even in micro-benchmarks.
 157
 158 config FUNCTION_GRAPH_TRACER
 159         bool "Kernel Function Graph Tracer"
 160         depends on HAVE_FUNCTION_GRAPH_TRACER
 161         depends on FUNCTION_TRACER
 162         depends on !X86_32 || !CC_OPTIMIZE_FOR_SIZE
 163         default y
 164         help
 165           Enable the kernel to trace a function at both its return
 166           and its entry.
 167           Its first purpose is to trace the duration of functions and
 168           draw a call graph for each thread with some information like
 169           the return value. This is done by setting the current return
 170           address on the current task structure into a stack of calls.
 171
 172
 173 config IRQSOFF_TRACER
 174         bool "Interrupts-off Latency Tracer"
 175         default n
 176         depends on TRACE_IRQFLAGS_SUPPORT
 177         depends on !ARCH_USES_GETTIMEOFFSET
 178         select TRACE_IRQFLAGS
 179         select GENERIC_TRACER
 180         select TRACER_MAX_TRACE
 181         select RING_BUFFER_ALLOW_SWAP
 182         select TRACER_SNAPSHOT
 183         select TRACER_SNAPSHOT_PER_CPU_SWAP
 184         help
 185           This option measures the time spent in irqs-off critical
 186           sections, with microsecond accuracy.
 187
 188           The default measurement method is a maximum search, which is
 189           disabled by default and can be runtime (re-)started
 190           via:
 191
 192               echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
 193
 194           (Note that kernel size and overhead increase with this option
 195           enabled. This option and the preempt-off timing option can be
 196           used together or separately.)
 197
 198 config PREEMPT_TRACER
 199         bool "Preemption-off Latency Tracer"
 200         default n
 201         depends on !ARCH_USES_GETTIMEOFFSET
 202         depends on PREEMPT
 203         select GENERIC_TRACER
 204         select TRACER_MAX_TRACE
 205         select RING_BUFFER_ALLOW_SWAP
 206         select TRACER_SNAPSHOT
 207         select TRACER_SNAPSHOT_PER_CPU_SWAP
 208         help
 209           This option measures the time spent in preemption-off critical
 210           sections, with microsecond accuracy.
 211
 212           The default measurement method is a maximum search, which is
 213           disabled by default and can be runtime (re-)started
 214           via:
 215
 216               echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
 217
 218           (Note that kernel size and overhead increase with this option
 219           enabled. This option and the irqs-off timing option can be
 220           used together or separately.)
 221
 222 config SCHED_TRACER
 223         bool "Scheduling Latency Tracer"
 224         select GENERIC_TRACER
 225         select CONTEXT_SWITCH_TRACER
 226         select TRACER_MAX_TRACE
 227         select TRACER_SNAPSHOT
 228         help
 229           This tracer tracks the latency of the highest priority task
 230           to be scheduled in, starting from the point it has woken up.
 231
 232 config ENABLE_DEFAULT_TRACERS
 233         bool "Trace process context switches and events"
 234         depends on !GENERIC_TRACER
 235         select TRACING
 236         help
 237           This tracer hooks to various trace points in the kernel,
 238           allowing the user to pick and choose which trace point they
 239           want to trace. It also includes the sched_switch tracer plugin.
 240
 241 config FTRACE_SYSCALLS
 242         bool "Trace syscalls"
 243         depends on HAVE_SYSCALL_TRACEPOINTS
 244         select GENERIC_TRACER
 245         select KALLSYMS
 246         help
 247           Basic tracer to catch the syscall entry and exit events.
 248
 249 config TRACER_SNAPSHOT
 250         bool "Create a snapshot trace buffer"
 251         select TRACER_MAX_TRACE
 252         help
 253           Allow tracing users to take snapshot of the current buffer using the
 254           ftrace interface, e.g.:
 255
 256               echo 1 > /sys/kernel/debug/tracing/snapshot
 257               cat snapshot
 258
 259 config TRACER_SNAPSHOT_PER_CPU_SWAP
 260         bool "Allow snapshot to swap per CPU"
 261         depends on TRACER_SNAPSHOT
 262         select RING_BUFFER_ALLOW_SWAP
 263         help
 264           Allow doing a snapshot of a single CPU buffer instead of a
 265           full swap (all buffers). If this is set, then the following is
 266           allowed:
 267
 268               echo 1 > /sys/kernel/debug/tracing/per_cpu/cpu2/snapshot
 269
 270           After which, only the tracing buffer for CPU 2 was swapped with
 271           the main tracing buffer, and the other CPU buffers remain the same.
 272
 273           When this is enabled, this adds a little more overhead to the
 274           trace recording, as it needs to add some checks to synchronize
 275           recording with swaps. But this does not affect the performance
 276           of the overall system. This is enabled by default when the preempt
 277           or irq latency tracers are enabled, as those need to swap as well
 278           and already adds the overhead (plus a lot more).
 279
 280 config TRACE_BRANCH_PROFILING
 281         bool
 282         select GENERIC_TRACER
 283
 284 choice
 285         prompt "Branch Profiling"
 286         default BRANCH_PROFILE_NONE
 287         help
 288          The branch profiling is a software profiler. It will add hooks
 289          into the C conditionals to test which path a branch takes.
 290
 291          The likely/unlikely profiler only looks at the conditions that
 292          are annotated with a likely or unlikely macro.
 293
 294          The "all branch" profiler will profile every if-statement in the
 295          kernel. This profiler will also enable the likely/unlikely
 296          profiler.
 297
 298          Either of the above profilers adds a bit of overhead to the system.
 299          If unsure, choose "No branch profiling".
 300
 301 config BRANCH_PROFILE_NONE
 302         bool "No branch profiling"
 303         help
 304           No branch profiling. Branch profiling adds a bit of overhead.
 305           Only enable it if you want to analyse the branching behavior.
 306           Otherwise keep it disabled.
 307
 308 config PROFILE_ANNOTATED_BRANCHES
 309         bool "Trace likely/unlikely profiler"
 310         select TRACE_BRANCH_PROFILING
 311         help
 312           This tracer profiles all likely and unlikely macros
 313           in the kernel. It will display the results in:
 314
 315           /sys/kernel/debug/tracing/trace_stat/branch_annotated
 316
 317           Note: this will add a significant overhead; only turn this
 318           on if you need to profile the system's use of these macros.
 319
 320 config PROFILE_ALL_BRANCHES
 321         bool "Profile all if conditionals"
 322         select TRACE_BRANCH_PROFILING
 323         help
 324           This tracer profiles all branch conditions. Every if ()
 325           taken in the kernel is recorded whether it hit or miss.
 326           The results will be displayed in:
 327
 328           /sys/kernel/debug/tracing/trace_stat/branch_all
 329
 330           This option also enables the likely/unlikely profiler.
 331
 332           This configuration, when enabled, will impose a great overhead
 333           on the system. This should only be enabled when the system
 334           is to be analyzed in much detail.
 335 endchoice
 336
 337 config TRACING_BRANCHES
 338         bool
 339         help
 340           Selected by tracers that will trace the likely and unlikely
 341           conditions. This prevents the tracers themselves from being
 342           profiled. Profiling the tracing infrastructure can only happen
 343           when the likelys and unlikelys are not being traced.
 344
 345 config BRANCH_TRACER
 346         bool "Trace likely/unlikely instances"
 347         depends on TRACE_BRANCH_PROFILING
 348         select TRACING_BRANCHES
 349         help
 350           This traces the events of likely and unlikely condition
 351           calls in the kernel.  The difference between this and the
 352           "Trace likely/unlikely profiler" is that this is not a
 353           histogram of the callers, but actually places the calling
 354           events into a running trace buffer to see when and where the
 355           events happened, as well as their results.
 356
 357           Say N if unsure.
 358
 359 config STACK_TRACER
 360         bool "Trace max stack"
 361         depends on HAVE_FUNCTION_TRACER
 362         select FUNCTION_TRACER
 363         select STACKTRACE
 364         select KALLSYMS
 365         help
 366           This special tracer records the maximum stack footprint of the
 367           kernel and displays it in /sys/kernel/debug/tracing/stack_trace.
 368
 369           This tracer works by hooking into every function call that the
 370           kernel executes, and keeping a maximum stack depth value and
 371           stack-trace saved.  If this is configured with DYNAMIC_FTRACE
 372           then it will not have any overhead while the stack tracer
 373           is disabled.
 374
 375           To enable the stack tracer on bootup, pass in 'stacktrace'
 376           on the kernel command line.
 377
 378           The stack tracer can also be enabled or disabled via the
 379           sysctl kernel.stack_tracer_enabled
 380
 381           Say N if unsure.
 382
 383 config BLK_DEV_IO_TRACE
 384         bool "Support for tracing block IO actions"
 385         depends on SYSFS
 386         depends on BLOCK
 387         select RELAY
 388         select DEBUG_FS
 389         select TRACEPOINTS
 390         select GENERIC_TRACER
 391         select STACKTRACE
 392         help
 393           Say Y here if you want to be able to trace the block layer actions
 394           on a given queue. Tracing allows you to see any traffic happening
 395           on a block device queue. For more information (and the userspace
 396           support tools needed), fetch the blktrace tools from:
 397
 398           git://git.kernel.dk/blktrace.git
 399
 400           Tracing also is possible using the ftrace interface, e.g.:
 401
 402             echo 1 > /sys/block/sda/sda1/trace/enable
 403             echo blk > /sys/kernel/debug/tracing/current_tracer
 404             cat /sys/kernel/debug/tracing/trace_pipe
 405
 406           If unsure, say N.
 407
 408 config KPROBE_EVENT
 409         depends on KPROBES
 410         depends on HAVE_REGS_AND_STACK_ACCESS_API
 411         bool "Enable kprobes-based dynamic events"
 412         select TRACING
 413         select PROBE_EVENTS
 414         default y
 415         help
 416           This allows the user to add tracing events (similar to tracepoints)
 417           on the fly via the ftrace interface. See
 418           Documentation/trace/kprobetrace.txt for more details.
 419
 420           Those events can be inserted wherever kprobes can probe, and record
 421           various register and memory values.
 422
 423           This option is also required by perf-probe subcommand of perf tools.
 424           If you want to use perf tools, this option is strongly recommended.
 425
 426 config UPROBE_EVENT
 427         bool "Enable uprobes-based dynamic events"
 428         depends on ARCH_SUPPORTS_UPROBES
 429         depends on MMU
 430         select UPROBES
 431         select PROBE_EVENTS
 432         select TRACING
 433         default n
 434         help
 435           This allows the user to add tracing events on top of userspace
 436           dynamic events (similar to tracepoints) on the fly via the trace
 437           events interface. Those events can be inserted wherever uprobes
 438           can probe, and record various registers.
 439           This option is required if you plan to use perf-probe subcommand
 440           of perf tools on user space applications.
 441
 442 config PROBE_EVENTS
 443         def_bool n
 444
 445 config DYNAMIC_FTRACE
 446         bool "enable/disable function tracing dynamically"
 447         depends on FUNCTION_TRACER
 448         depends on HAVE_DYNAMIC_FTRACE
 449         default y
 450         help
 451           This option will modify all the calls to function tracing
 452           dynamically (will patch them out of the binary image and
 453           replace them with a No-Op instruction) on boot up. During
 454           compile time, a table is made of all the locations that ftrace
 455           can function trace, and this table is linked into the kernel
 456           image. When this is enabled, functions can be individually
 457           enabled, and the functions not enabled will not affect
 458           performance of the system.
 459
 460           See the files in /sys/kernel/debug/tracing:
 461             available_filter_functions
 462             set_ftrace_filter
 463             set_ftrace_notrace
 464
 465           This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but
 466           otherwise has native performance as long as no tracing is active.
 467
 468 config DYNAMIC_FTRACE_WITH_REGS
 469         def_bool y
 470         depends on DYNAMIC_FTRACE
 471         depends on HAVE_DYNAMIC_FTRACE_WITH_REGS
 472
 473 config FUNCTION_PROFILER
 474         bool "Kernel function profiler"
 475         depends on FUNCTION_TRACER
 476         default n
 477         help
 478           This option enables the kernel function profiler. A file is created
 479           in debugfs called function_profile_enabled which defaults to zero.
 480           When a 1 is echoed into this file profiling begins, and when a
 481           zero is entered, profiling stops. A "functions" file is created in
 482           the trace_stats directory; this file shows the list of functions that
 483           have been hit and their counters.
 484
 485           If in doubt, say N.
 486
 487 config FTRACE_MCOUNT_RECORD
 488         def_bool y
 489         depends on DYNAMIC_FTRACE
 490         depends on HAVE_FTRACE_MCOUNT_RECORD
 491
 492 config FTRACE_SELFTEST
 493         bool
 494
 495 config FTRACE_STARTUP_TEST
 496         bool "Perform a startup test on ftrace"
 497         depends on GENERIC_TRACER
 498         select FTRACE_SELFTEST
 499         help
 500           This option performs a series of startup tests on ftrace. On bootup
 501           a series of tests are made to verify that the tracer is
 502           functioning properly. It will do tests on all the configured
 503           tracers of ftrace.
 504
 505 config EVENT_TRACE_TEST_SYSCALLS
 506         bool "Run selftest on syscall events"
 507         depends on FTRACE_STARTUP_TEST
 508         help
 509          This option will also enable testing every syscall event.
 510          It only enables the event and disables it and runs various loads
 511          with the event enabled. This adds a bit more time for kernel boot
 512          up since it runs this on every system call defined.
 513
 514          TBD - enable a way to actually call the syscalls as we test their
 515                events
 516
 517 config MMIOTRACE
 518         bool "Memory mapped IO tracing"
 519         depends on HAVE_MMIOTRACE_SUPPORT && PCI
 520         select GENERIC_TRACER
 521         help
 522           Mmiotrace traces Memory Mapped I/O access and is meant for
 523           debugging and reverse engineering. It is called from the ioremap
 524           implementation and works via page faults. Tracing is disabled by
 525           default and can be enabled at run-time.
 526
 527           See Documentation/trace/mmiotrace.txt.
 528           If you are not helping to develop drivers, say N.
 529
 530 config MMIOTRACE_TEST
 531         tristate "Test module for mmiotrace"
 532         depends on MMIOTRACE && m
 533         help
 534           This is a dumb module for testing mmiotrace. It is very dangerous
 535           as it will write garbage to IO memory starting at a given address.
 536           However, it should be safe to use on e.g. unused portion of VRAM.
 537
 538           Say N, unless you absolutely know what you are doing.
 539
 540 config RING_BUFFER_BENCHMARK
 541         tristate "Ring buffer benchmark stress tester"
 542         depends on RING_BUFFER
 543         help
 544           This option creates a test to stress the ring buffer and benchmark it.
 545           It creates its own ring buffer such that it will not interfere with
 546           any other users of the ring buffer (such as ftrace). It then creates
 547           a producer and consumer that will run for 10 seconds and sleep for
 548           10 seconds. Each interval it will print out the number of events
 549           it recorded and give a rough estimate of how long each iteration took.
 550
 551           It does not disable interrupts or raise its priority, so it may be
 552           affected by processes that are running.
 553
 554           If unsure, say N.
 555
 556 config RING_BUFFER_STARTUP_TEST
 557        bool "Ring buffer startup self test"
 558        depends on RING_BUFFER
 559        help
 560          Run a simple self test on the ring buffer on boot up. Late in the
 561          kernel boot sequence, the test will start that kicks off
 562          a thread per cpu. Each thread will write various size events
 563          into the ring buffer. Another thread is created to send IPIs
 564          to each of the threads, where the IPI handler will also write
 565          to the ring buffer, to test/stress the nesting ability.
 566          If any anomalies are discovered, a warning will be displayed
 567          and all ring buffers will be disabled.
 568
 569          The test runs for 10 seconds. This will slow your boot time
 570          by at least 10 more seconds.
 571
 572          At the end of the test, statics and more checks are done.
 573          It will output the stats of each per cpu buffer. What
 574          was written, the sizes, what was read, what was lost, and
 575          other similar details.
 576
 577          If unsure, say N
 578
 579 endif # FTRACE
 580
 581 endif # TRACING_SUPPORT
 582