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          An arch may pass in a unique value (frame pointer) to both the
  31          entering and exiting of a function. On exit, the value is compared
  32          and if it does not match, then it will panic the kernel.
  33
  34 config HAVE_FUNCTION_TRACE_MCOUNT_TEST
  35         bool
  36         help
  37           See Documentation/trace/ftrace-design.txt
  38
  39 config HAVE_DYNAMIC_FTRACE
  40         bool
  41         help
  42           See Documentation/trace/ftrace-design.txt
  43
  44 config HAVE_FTRACE_MCOUNT_RECORD
  45         bool
  46         help
  47           See Documentation/trace/ftrace-design.txt
  48
  49 config HAVE_HW_BRANCH_TRACER
  50         bool
  51
  52 config HAVE_SYSCALL_TRACEPOINTS
  53         bool
  54         help
  55           See Documentation/trace/ftrace-design.txt
  56
  57 config TRACER_MAX_TRACE
  58         bool
  59
  60 config RING_BUFFER
  61         bool
  62
  63 config FTRACE_NMI_ENTER
  64        bool
  65        depends on HAVE_FTRACE_NMI_ENTER
  66        default y
  67
  68 config EVENT_TRACING
  69         select CONTEXT_SWITCH_TRACER
  70         bool
  71
  72 config CONTEXT_SWITCH_TRACER
  73         bool
  74
  75 config RING_BUFFER_ALLOW_SWAP
  76         bool
  77         help
  78          Allow the use of ring_buffer_swap_cpu.
  79          Adds a very slight overhead to tracing when enabled.
  80
  81 # All tracer options should select GENERIC_TRACER. For those options that are
  82 # enabled by all tracers (context switch and event tracer) they select TRACING.
  83 # This allows those options to appear when no other tracer is selected. But the
  84 # options do not appear when something else selects it. We need the two options
  85 # GENERIC_TRACER and TRACING to avoid circular dependencies to accomplish the
  86 # hiding of the automatic options.
  87
  88 config TRACING
  89         bool
  90         select DEBUG_FS
  91         select RING_BUFFER
  92         select STACKTRACE if STACKTRACE_SUPPORT
  93         select TRACEPOINTS
  94         select NOP_TRACER
  95         select BINARY_PRINTF
  96         select EVENT_TRACING
  97
  98 config GENERIC_TRACER
  99         bool
 100         select TRACING
 101
 102 #
 103 # Minimum requirements an architecture has to meet for us to
 104 # be able to offer generic tracing facilities:
 105 #
 106 config TRACING_SUPPORT
 107         bool
 108         # PPC32 has no irqflags tracing support, but it can use most of the
 109         # tracers anyway, they were tested to build and work. Note that new
 110         # exceptions to this list aren't welcomed, better implement the
 111         # irqflags tracing for your architecture.
 112         depends on TRACE_IRQFLAGS_SUPPORT || PPC32
 113         depends on STACKTRACE_SUPPORT
 114         default y
 115
 116 if TRACING_SUPPORT
 117
 118 menuconfig FTRACE
 119         bool "Tracers"
 120         default y if DEBUG_KERNEL
 121         help
 122           Enable the kernel tracing infrastructure.
 123
 124 if FTRACE
 125
 126 config FUNCTION_TRACER
 127         bool "Kernel Function Tracer"
 128         depends on HAVE_FUNCTION_TRACER
 129         select FRAME_POINTER
 130         select KALLSYMS
 131         select GENERIC_TRACER
 132         select CONTEXT_SWITCH_TRACER
 133         help
 134           Enable the kernel to trace every kernel function. This is done
 135           by using a compiler feature to insert a small, 5-byte No-Operation
 136           instruction at the beginning of every kernel function, which NOP
 137           sequence is then dynamically patched into a tracer call when
 138           tracing is enabled by the administrator. If it's runtime disabled
 139           (the bootup default), then the overhead of the instructions is very
 140           small and not measurable even in micro-benchmarks.
 141
 142 config FUNCTION_GRAPH_TRACER
 143         bool "Kernel Function Graph Tracer"
 144         depends on HAVE_FUNCTION_GRAPH_TRACER
 145         depends on FUNCTION_TRACER
 146         depends on !X86_32 || !CC_OPTIMIZE_FOR_SIZE
 147         default y
 148         help
 149           Enable the kernel to trace a function at both its return
 150           and its entry.
 151           Its first purpose is to trace the duration of functions and
 152           draw a call graph for each thread with some information like
 153           the return value. This is done by setting the current return
 154           address on the current task structure into a stack of calls.
 155
 156
 157 config IRQSOFF_TRACER
 158         bool "Interrupts-off Latency Tracer"
 159         default n
 160         depends on TRACE_IRQFLAGS_SUPPORT
 161         depends on GENERIC_TIME
 162         select TRACE_IRQFLAGS
 163         select GENERIC_TRACER
 164         select TRACER_MAX_TRACE
 165         select RING_BUFFER_ALLOW_SWAP
 166         help
 167           This option measures the time spent in irqs-off critical
 168           sections, with microsecond accuracy.
 169
 170           The default measurement method is a maximum search, which is
 171           disabled by default and can be runtime (re-)started
 172           via:
 173
 174               echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
 175
 176           (Note that kernel size and overhead increase with this option
 177           enabled. This option and the preempt-off timing option can be
 178           used together or separately.)
 179
 180 config PREEMPT_TRACER
 181         bool "Preemption-off Latency Tracer"
 182         default n
 183         depends on GENERIC_TIME
 184         depends on PREEMPT
 185         select GENERIC_TRACER
 186         select TRACER_MAX_TRACE
 187         select RING_BUFFER_ALLOW_SWAP
 188         help
 189           This option measures the time spent in preemption-off critical
 190           sections, with microsecond accuracy.
 191
 192           The default measurement method is a maximum search, which is
 193           disabled by default and can be runtime (re-)started
 194           via:
 195
 196               echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
 197
 198           (Note that kernel size and overhead increase with this option
 199           enabled. This option and the irqs-off timing option can be
 200           used together or separately.)
 201
 202 config SYSPROF_TRACER
 203         bool "Sysprof Tracer"
 204         depends on X86
 205         select GENERIC_TRACER
 206         select CONTEXT_SWITCH_TRACER
 207         help
 208           This tracer provides the trace needed by the 'Sysprof' userspace
 209           tool.
 210
 211 config SCHED_TRACER
 212         bool "Scheduling Latency Tracer"
 213         select GENERIC_TRACER
 214         select CONTEXT_SWITCH_TRACER
 215         select TRACER_MAX_TRACE
 216         help
 217           This tracer tracks the latency of the highest priority task
 218           to be scheduled in, starting from the point it has woken up.
 219
 220 config ENABLE_DEFAULT_TRACERS
 221         bool "Trace process context switches and events"
 222         depends on !GENERIC_TRACER
 223         select TRACING
 224         help
 225           This tracer hooks to various trace points in the kernel,
 226           allowing the user to pick and choose which trace point they
 227           want to trace. It also includes the sched_switch tracer plugin.
 228
 229 config FTRACE_SYSCALLS
 230         bool "Trace syscalls"
 231         depends on HAVE_SYSCALL_TRACEPOINTS
 232         select GENERIC_TRACER
 233         select KALLSYMS
 234         help
 235           Basic tracer to catch the syscall entry and exit events.
 236
 237 config BOOT_TRACER
 238         bool "Trace boot initcalls"
 239         select GENERIC_TRACER
 240         select CONTEXT_SWITCH_TRACER
 241         help
 242           This tracer helps developers to optimize boot times: it records
 243           the timings of the initcalls and traces key events and the identity
 244           of tasks that can cause boot delays, such as context-switches.
 245
 246           Its aim is to be parsed by the scripts/bootgraph.pl tool to
 247           produce pretty graphics about boot inefficiencies, giving a visual
 248           representation of the delays during initcalls - but the raw
 249           /debug/tracing/trace text output is readable too.
 250
 251           You must pass in initcall_debug and ftrace=initcall to the kernel
 252           command line to enable this on bootup.
 253
 254 config TRACE_BRANCH_PROFILING
 255         bool
 256         select GENERIC_TRACER
 257
 258 choice
 259         prompt "Branch Profiling"
 260         default BRANCH_PROFILE_NONE
 261         help
 262          The branch profiling is a software profiler. It will add hooks
 263          into the C conditionals to test which path a branch takes.
 264
 265          The likely/unlikely profiler only looks at the conditions that
 266          are annotated with a likely or unlikely macro.
 267
 268          The "all branch" profiler will profile every if-statement in the
 269          kernel. This profiler will also enable the likely/unlikely
 270          profiler.
 271
 272          Either of the above profilers adds a bit of overhead to the system.
 273          If unsure, choose "No branch profiling".
 274
 275 config BRANCH_PROFILE_NONE
 276         bool "No branch profiling"
 277         help
 278           No branch profiling. Branch profiling adds a bit of overhead.
 279           Only enable it if you want to analyse the branching behavior.
 280           Otherwise keep it disabled.
 281
 282 config PROFILE_ANNOTATED_BRANCHES
 283         bool "Trace likely/unlikely profiler"
 284         select TRACE_BRANCH_PROFILING
 285         help
 286           This tracer profiles all the the likely and unlikely macros
 287           in the kernel. It will display the results in:
 288
 289           /sys/kernel/debug/tracing/profile_annotated_branch
 290
 291           Note: this will add a significant overhead; only turn this
 292           on if you need to profile the system's use of these macros.
 293
 294 config PROFILE_ALL_BRANCHES
 295         bool "Profile all if conditionals"
 296         select TRACE_BRANCH_PROFILING
 297         help
 298           This tracer profiles all branch conditions. Every if ()
 299           taken in the kernel is recorded whether it hit or miss.
 300           The results will be displayed in:
 301
 302           /sys/kernel/debug/tracing/profile_branch
 303
 304           This option also enables the likely/unlikely profiler.
 305
 306           This configuration, when enabled, will impose a great overhead
 307           on the system. This should only be enabled when the system
 308           is to be analyzed in much detail.
 309 endchoice
 310
 311 config TRACING_BRANCHES
 312         bool
 313         help
 314           Selected by tracers that will trace the likely and unlikely
 315           conditions. This prevents the tracers themselves from being
 316           profiled. Profiling the tracing infrastructure can only happen
 317           when the likelys and unlikelys are not being traced.
 318
 319 config BRANCH_TRACER
 320         bool "Trace likely/unlikely instances"
 321         depends on TRACE_BRANCH_PROFILING
 322         select TRACING_BRANCHES
 323         help
 324           This traces the events of likely and unlikely condition
 325           calls in the kernel.  The difference between this and the
 326           "Trace likely/unlikely profiler" is that this is not a
 327           histogram of the callers, but actually places the calling
 328           events into a running trace buffer to see when and where the
 329           events happened, as well as their results.
 330
 331           Say N if unsure.
 332
 333 config KSYM_TRACER
 334         bool "Trace read and write access on kernel memory locations"
 335         depends on HAVE_HW_BREAKPOINT
 336         select TRACING
 337         help
 338           This tracer helps find read and write operations on any given kernel
 339           symbol i.e. /proc/kallsyms.
 340
 341 config PROFILE_KSYM_TRACER
 342         bool "Profile all kernel memory accesses on 'watched' variables"
 343         depends on KSYM_TRACER
 344         help
 345           This tracer profiles kernel accesses on variables watched through the
 346           ksym tracer ftrace plugin. Depending upon the hardware, all read
 347           and write operations on kernel variables can be monitored for
 348           accesses.
 349
 350           The results will be displayed in:
 351           /debugfs/tracing/profile_ksym
 352
 353           Say N if unsure.
 354
 355 config STACK_TRACER
 356         bool "Trace max stack"
 357         depends on HAVE_FUNCTION_TRACER
 358         select FUNCTION_TRACER
 359         select STACKTRACE
 360         select KALLSYMS
 361         help
 362           This special tracer records the maximum stack footprint of the
 363           kernel and displays it in /sys/kernel/debug/tracing/stack_trace.
 364
 365           This tracer works by hooking into every function call that the
 366           kernel executes, and keeping a maximum stack depth value and
 367           stack-trace saved.  If this is configured with DYNAMIC_FTRACE
 368           then it will not have any overhead while the stack tracer
 369           is disabled.
 370
 371           To enable the stack tracer on bootup, pass in 'stacktrace'
 372           on the kernel command line.
 373
 374           The stack tracer can also be enabled or disabled via the
 375           sysctl kernel.stack_tracer_enabled
 376
 377           Say N if unsure.
 378
 379 config HW_BRANCH_TRACER
 380         depends on HAVE_HW_BRANCH_TRACER
 381         bool "Trace hw branches"
 382         select GENERIC_TRACER
 383         help
 384           This tracer records all branches on the system in a circular
 385           buffer, giving access to the last N branches for each cpu.
 386
 387 config KMEMTRACE
 388         bool "Trace SLAB allocations"
 389         select GENERIC_TRACER
 390         help
 391           kmemtrace provides tracing for slab allocator functions, such as
 392           kmalloc, kfree, kmem_cache_alloc, kmem_cache_free, etc. Collected
 393           data is then fed to the userspace application in order to analyse
 394           allocation hotspots, internal fragmentation and so on, making it
 395           possible to see how well an allocator performs, as well as debug
 396           and profile kernel code.
 397
 398           This requires an userspace application to use. See
 399           Documentation/trace/kmemtrace.txt for more information.
 400
 401           Saying Y will make the kernel somewhat larger and slower. However,
 402           if you disable kmemtrace at run-time or boot-time, the performance
 403           impact is minimal (depending on the arch the kernel is built for).
 404
 405           If unsure, say N.
 406
 407 config WORKQUEUE_TRACER
 408         bool "Trace workqueues"
 409         select GENERIC_TRACER
 410         help
 411           The workqueue tracer provides some statistical information
 412           about each cpu workqueue thread such as the number of the
 413           works inserted and executed since their creation. It can help
 414           to evaluate the amount of work each of them has to perform.
 415           For example it can help a developer to decide whether he should
 416           choose a per-cpu workqueue instead of a singlethreaded one.
 417
 418 config BLK_DEV_IO_TRACE
 419         bool "Support for tracing block IO actions"
 420         depends on SYSFS
 421         depends on BLOCK
 422         select RELAY
 423         select DEBUG_FS
 424         select TRACEPOINTS
 425         select GENERIC_TRACER
 426         select STACKTRACE
 427         help
 428           Say Y here if you want to be able to trace the block layer actions
 429           on a given queue. Tracing allows you to see any traffic happening
 430           on a block device queue. For more information (and the userspace
 431           support tools needed), fetch the blktrace tools from:
 432
 433           git://git.kernel.dk/blktrace.git
 434
 435           Tracing also is possible using the ftrace interface, e.g.:
 436
 437             echo 1 > /sys/block/sda/sda1/trace/enable
 438             echo blk > /sys/kernel/debug/tracing/current_tracer
 439             cat /sys/kernel/debug/tracing/trace_pipe
 440
 441           If unsure, say N.
 442
 443 config KPROBE_EVENT
 444         depends on KPROBES
 445         depends on X86
 446         bool "Enable kprobes-based dynamic events"
 447         select TRACING
 448         default y
 449         help
 450           This allows the user to add tracing events (similar to tracepoints)
 451           on the fly via the ftrace interface. See
 452           Documentation/trace/kprobetrace.txt for more details.
 453
 454           Those events can be inserted wherever kprobes can probe, and record
 455           various register and memory values.
 456
 457           This option is also required by perf-probe subcommand of perf tools.
 458           If you want to use perf tools, this option is strongly recommended.
 459
 460 config DYNAMIC_FTRACE
 461         bool "enable/disable ftrace tracepoints dynamically"
 462         depends on FUNCTION_TRACER
 463         depends on HAVE_DYNAMIC_FTRACE
 464         default y
 465         help
 466           This option will modify all the calls to ftrace dynamically
 467           (will patch them out of the binary image and replace them
 468           with a No-Op instruction) as they are called. A table is
 469           created to dynamically enable them again.
 470
 471           This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but
 472           otherwise has native performance as long as no tracing is active.
 473
 474           The changes to the code are done by a kernel thread that
 475           wakes up once a second and checks to see if any ftrace calls
 476           were made. If so, it runs stop_machine (stops all CPUS)
 477           and modifies the code to jump over the call to ftrace.
 478
 479 config FUNCTION_PROFILER
 480         bool "Kernel function profiler"
 481         depends on FUNCTION_TRACER
 482         default n
 483         help
 484           This option enables the kernel function profiler. A file is created
 485           in debugfs called function_profile_enabled which defaults to zero.
 486           When a 1 is echoed into this file profiling begins, and when a
 487           zero is entered, profiling stops. A "functions" file is created in
 488           the trace_stats directory; this file shows the list of functions that
 489           have been hit and their counters.
 490
 491           If in doubt, say N.
 492
 493 config FTRACE_MCOUNT_RECORD
 494         def_bool y
 495         depends on DYNAMIC_FTRACE
 496         depends on HAVE_FTRACE_MCOUNT_RECORD
 497
 498 config FTRACE_SELFTEST
 499         bool
 500
 501 config FTRACE_STARTUP_TEST
 502         bool "Perform a startup test on ftrace"
 503         depends on GENERIC_TRACER
 504         select FTRACE_SELFTEST
 505         help
 506           This option performs a series of startup tests on ftrace. On bootup
 507           a series of tests are made to verify that the tracer is
 508           functioning properly. It will do tests on all the configured
 509           tracers of ftrace.
 510
 511 config EVENT_TRACE_TEST_SYSCALLS
 512         bool "Run selftest on syscall events"
 513         depends on FTRACE_STARTUP_TEST
 514         help
 515          This option will also enable testing every syscall event.
 516          It only enables the event and disables it and runs various loads
 517          with the event enabled. This adds a bit more time for kernel boot
 518          up since it runs this on every system call defined.
 519
 520          TBD - enable a way to actually call the syscalls as we test their
 521                events
 522
 523 config MMIOTRACE
 524         bool "Memory mapped IO tracing"
 525         depends on HAVE_MMIOTRACE_SUPPORT && PCI
 526         select GENERIC_TRACER
 527         help
 528           Mmiotrace traces Memory Mapped I/O access and is meant for
 529           debugging and reverse engineering. It is called from the ioremap
 530           implementation and works via page faults. Tracing is disabled by
 531           default and can be enabled at run-time.
 532
 533           See Documentation/trace/mmiotrace.txt.
 534           If you are not helping to develop drivers, say N.
 535
 536 config MMIOTRACE_TEST
 537         tristate "Test module for mmiotrace"
 538         depends on MMIOTRACE && m
 539         help
 540           This is a dumb module for testing mmiotrace. It is very dangerous
 541           as it will write garbage to IO memory starting at a given address.
 542           However, it should be safe to use on e.g. unused portion of VRAM.
 543
 544           Say N, unless you absolutely know what you are doing.
 545
 546 config RING_BUFFER_BENCHMARK
 547         tristate "Ring buffer benchmark stress tester"
 548         depends on RING_BUFFER
 549         help
 550           This option creates a test to stress the ring buffer and benchmark it.
 551           It creates its own ring buffer such that it will not interfere with
 552           any other users of the ring buffer (such as ftrace). It then creates
 553           a producer and consumer that will run for 10 seconds and sleep for
 554           10 seconds. Each interval it will print out the number of events
 555           it recorded and give a rough estimate of how long each iteration took.
 556
 557           It does not disable interrupts or raise its priority, so it may be
 558           affected by processes that are running.
 559
 560           If unsure, say N.
 561
 562 endif # FTRACE
 563
 564 endif # TRACING_SUPPORT
 565