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