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