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
  15 config HAVE_FUNCTION_TRACER
  16         bool
  17
  18 config HAVE_FUNCTION_GRAPH_TRACER
  19         bool
  20
  21 config HAVE_FUNCTION_TRACE_MCOUNT_TEST
  22         bool
  23         help
  24          This gets selected when the arch tests the function_trace_stop
  25          variable at the mcount call site. Otherwise, this variable
  26          is tested by the called function.
  27
  28 config HAVE_DYNAMIC_FTRACE
  29         bool
  30
  31 config HAVE_FTRACE_MCOUNT_RECORD
  32         bool
  33
  34 config HAVE_HW_BRANCH_TRACER
  35         bool
  36
  37 config TRACER_MAX_TRACE
  38         bool
  39
  40 config RING_BUFFER
  41         bool
  42
  43 config FTRACE_NMI_ENTER
  44        bool
  45        depends on HAVE_FTRACE_NMI_ENTER
  46        default y
  47
  48 config TRACING
  49         bool
  50         select DEBUG_FS
  51         select RING_BUFFER
  52         select STACKTRACE if STACKTRACE_SUPPORT
  53         select TRACEPOINTS
  54         select NOP_TRACER
  55
  56 menu "Tracers"
  57
  58 config FUNCTION_TRACER
  59         bool "Kernel Function Tracer"
  60         depends on HAVE_FUNCTION_TRACER
  61         depends on DEBUG_KERNEL
  62         select FRAME_POINTER
  63         select KALLSYMS
  64         select TRACING
  65         select CONTEXT_SWITCH_TRACER
  66         help
  67           Enable the kernel to trace every kernel function. This is done
  68           by using a compiler feature to insert a small, 5-byte No-Operation
  69           instruction to the beginning of every kernel function, which NOP
  70           sequence is then dynamically patched into a tracer call when
  71           tracing is enabled by the administrator. If it's runtime disabled
  72           (the bootup default), then the overhead of the instructions is very
  73           small and not measurable even in micro-benchmarks.
  74
  75 config FUNCTION_GRAPH_TRACER
  76         bool "Kernel Function Graph Tracer"
  77         depends on HAVE_FUNCTION_GRAPH_TRACER
  78         depends on FUNCTION_TRACER
  79         default y
  80         help
  81           Enable the kernel to trace a function at both its return
  82           and its entry.
  83           It's first purpose is to trace the duration of functions and
  84           draw a call graph for each thread with some informations like
  85           the return value.
  86           This is done by setting the current return address on the current
  87           task structure into a stack of calls.
  88
  89 config IRQSOFF_TRACER
  90         bool "Interrupts-off Latency Tracer"
  91         default n
  92         depends on TRACE_IRQFLAGS_SUPPORT
  93         depends on GENERIC_TIME
  94         depends on DEBUG_KERNEL
  95         select TRACE_IRQFLAGS
  96         select TRACING
  97         select TRACER_MAX_TRACE
  98         help
  99           This option measures the time spent in irqs-off critical
 100           sections, with microsecond accuracy.
 101
 102           The default measurement method is a maximum search, which is
 103           disabled by default and can be runtime (re-)started
 104           via:
 105
 106               echo 0 > /debugfs/tracing/tracing_max_latency
 107
 108           (Note that kernel size and overhead increases with this option
 109           enabled. This option and the preempt-off timing option can be
 110           used together or separately.)
 111
 112 config PREEMPT_TRACER
 113         bool "Preemption-off Latency Tracer"
 114         default n
 115         depends on GENERIC_TIME
 116         depends on PREEMPT
 117         depends on DEBUG_KERNEL
 118         select TRACING
 119         select TRACER_MAX_TRACE
 120         help
 121           This option measures the time spent in preemption off critical
 122           sections, with microsecond accuracy.
 123
 124           The default measurement method is a maximum search, which is
 125           disabled by default and can be runtime (re-)started
 126           via:
 127
 128               echo 0 > /debugfs/tracing/tracing_max_latency
 129
 130           (Note that kernel size and overhead increases with this option
 131           enabled. This option and the irqs-off timing option can be
 132           used together or separately.)
 133
 134 config SYSPROF_TRACER
 135         bool "Sysprof Tracer"
 136         depends on X86
 137         select TRACING
 138         select CONTEXT_SWITCH_TRACER
 139         help
 140           This tracer provides the trace needed by the 'Sysprof' userspace
 141           tool.
 142
 143 config SCHED_TRACER
 144         bool "Scheduling Latency Tracer"
 145         depends on DEBUG_KERNEL
 146         select TRACING
 147         select CONTEXT_SWITCH_TRACER
 148         select TRACER_MAX_TRACE
 149         help
 150           This tracer tracks the latency of the highest priority task
 151           to be scheduled in, starting from the point it has woken up.
 152
 153 config CONTEXT_SWITCH_TRACER
 154         bool "Trace process context switches"
 155         depends on DEBUG_KERNEL
 156         select TRACING
 157         select MARKERS
 158         help
 159           This tracer gets called from the context switch and records
 160           all switching of tasks.
 161
 162 config BOOT_TRACER
 163         bool "Trace boot initcalls"
 164         depends on DEBUG_KERNEL
 165         select TRACING
 166         select CONTEXT_SWITCH_TRACER
 167         help
 168           This tracer helps developers to optimize boot times: it records
 169           the timings of the initcalls and traces key events and the identity
 170           of tasks that can cause boot delays, such as context-switches.
 171
 172           Its aim is to be parsed by the /scripts/bootgraph.pl tool to
 173           produce pretty graphics about boot inefficiencies, giving a visual
 174           representation of the delays during initcalls - but the raw
 175           /debug/tracing/trace text output is readable too.
 176
 177           You must pass in ftrace=initcall to the kernel command line
 178           to enable this on bootup.
 179
 180 config TRACE_BRANCH_PROFILING
 181         bool "Trace likely/unlikely profiler"
 182         depends on DEBUG_KERNEL
 183         select TRACING
 184         help
 185           This tracer profiles all the the likely and unlikely macros
 186           in the kernel. It will display the results in:
 187
 188           /debugfs/tracing/profile_annotated_branch
 189
 190           Note: this will add a significant overhead, only turn this
 191           on if you need to profile the system's use of these macros.
 192
 193           Say N if unsure.
 194
 195 config PROFILE_ALL_BRANCHES
 196         bool "Profile all if conditionals"
 197         depends on TRACE_BRANCH_PROFILING
 198         help
 199           This tracer profiles all branch conditions. Every if ()
 200           taken in the kernel is recorded whether it hit or miss.
 201           The results will be displayed in:
 202
 203           /debugfs/tracing/profile_branch
 204
 205           This configuration, when enabled, will impose a great overhead
 206           on the system. This should only be enabled when the system
 207           is to be analyzed
 208
 209           Say N if unsure.
 210
 211 config TRACING_BRANCHES
 212         bool
 213         help
 214           Selected by tracers that will trace the likely and unlikely
 215           conditions. This prevents the tracers themselves from being
 216           profiled. Profiling the tracing infrastructure can only happen
 217           when the likelys and unlikelys are not being traced.
 218
 219 config BRANCH_TRACER
 220         bool "Trace likely/unlikely instances"
 221         depends on TRACE_BRANCH_PROFILING
 222         select TRACING_BRANCHES
 223         help
 224           This traces the events of likely and unlikely condition
 225           calls in the kernel.  The difference between this and the
 226           "Trace likely/unlikely profiler" is that this is not a
 227           histogram of the callers, but actually places the calling
 228           events into a running trace buffer to see when and where the
 229           events happened, as well as their results.
 230
 231           Say N if unsure.
 232
 233 config POWER_TRACER
 234         bool "Trace power consumption behavior"
 235         depends on DEBUG_KERNEL
 236         depends on X86
 237         select TRACING
 238         help
 239           This tracer helps developers to analyze and optimize the kernels
 240           power management decisions, specifically the C-state and P-state
 241           behavior.
 242
 243
 244 config STACK_TRACER
 245         bool "Trace max stack"
 246         depends on HAVE_FUNCTION_TRACER
 247         depends on DEBUG_KERNEL
 248         select FUNCTION_TRACER
 249         select STACKTRACE
 250         select KALLSYMS
 251         help
 252           This special tracer records the maximum stack footprint of the
 253           kernel and displays it in debugfs/tracing/stack_trace.
 254
 255           This tracer works by hooking into every function call that the
 256           kernel executes, and keeping a maximum stack depth value and
 257           stack-trace saved.  If this is configured with DYNAMIC_FTRACE
 258           then it will not have any overhead while the stack tracer
 259           is disabled.
 260
 261           To enable the stack tracer on bootup, pass in 'stacktrace'
 262           on the kernel command line.
 263
 264           The stack tracer can also be enabled or disabled via the
 265           sysctl kernel.stack_tracer_enabled
 266
 267           Say N if unsure.
 268
 269 config HW_BRANCH_TRACER
 270         depends on HAVE_HW_BRANCH_TRACER
 271         bool "Trace hw branches"
 272         select TRACING
 273         help
 274           This tracer records all branches on the system in a circular
 275           buffer giving access to the last N branches for each cpu.
 276
 277 config KMEMTRACE
 278         bool "Trace SLAB allocations"
 279         select TRACING
 280         help
 281           kmemtrace provides tracing for slab allocator functions, such as
 282           kmalloc, kfree, kmem_cache_alloc, kmem_cache_free etc.. Collected
 283           data is then fed to the userspace application in order to analyse
 284           allocation hotspots, internal fragmentation and so on, making it
 285           possible to see how well an allocator performs, as well as debug
 286           and profile kernel code.
 287
 288           This requires an userspace application to use. See
 289           Documentation/vm/kmemtrace.txt for more information.
 290
 291           Saying Y will make the kernel somewhat larger and slower. However,
 292           if you disable kmemtrace at run-time or boot-time, the performance
 293           impact is minimal (depending on the arch the kernel is built for).
 294
 295           If unsure, say N.
 296
 297 config WORKQUEUE_TRACER
 298         bool "Trace workqueues"
 299         select TRACING
 300         help
 301           The workqueue tracer provides some statistical informations
 302           about each cpu workqueue thread such as the number of the
 303           works inserted and executed since their creation. It can help
 304           to evaluate the amount of work each of them have to perform.
 305           For example it can help a developer to decide whether he should
 306           choose a per cpu workqueue instead of a singlethreaded one.
 307
 308 config BLK_DEV_IO_TRACE
 309         bool "Support for tracing block io actions"
 310         depends on SYSFS
 311         depends on BLOCK
 312         select RELAY
 313         select DEBUG_FS
 314         select TRACEPOINTS
 315         select TRACING
 316         select STACKTRACE
 317         help
 318           Say Y here if you want to be able to trace the block layer actions
 319           on a given queue. Tracing allows you to see any traffic happening
 320           on a block device queue. For more information (and the userspace
 321           support tools needed), fetch the blktrace tools from:
 322
 323           git://git.kernel.dk/blktrace.git
 324
 325           Tracing also is possible using the ftrace interface, e.g.:
 326
 327             echo 1 > /sys/block/sda/sda1/trace/enable
 328             echo blk > /sys/kernel/debug/tracing/current_tracer
 329             cat /sys/kernel/debug/tracing/trace_pipe
 330
 331           If unsure, say N.
 332
 333 config DYNAMIC_FTRACE
 334         bool "enable/disable ftrace tracepoints dynamically"
 335         depends on FUNCTION_TRACER
 336         depends on HAVE_DYNAMIC_FTRACE
 337         depends on DEBUG_KERNEL
 338         default y
 339         help
 340          This option will modify all the calls to ftrace dynamically
 341          (will patch them out of the binary image and replaces them
 342          with a No-Op instruction) as they are called. A table is
 343          created to dynamically enable them again.
 344
 345          This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but otherwise
 346          has native performance as long as no tracing is active.
 347
 348          The changes to the code are done by a kernel thread that
 349          wakes up once a second and checks to see if any ftrace calls
 350          were made. If so, it runs stop_machine (stops all CPUS)
 351          and modifies the code to jump over the call to ftrace.
 352
 353 config FTRACE_MCOUNT_RECORD
 354         def_bool y
 355         depends on DYNAMIC_FTRACE
 356         depends on HAVE_FTRACE_MCOUNT_RECORD
 357
 358 config FTRACE_SELFTEST
 359         bool
 360
 361 config FTRACE_STARTUP_TEST
 362         bool "Perform a startup test on ftrace"
 363         depends on TRACING && DEBUG_KERNEL
 364         select FTRACE_SELFTEST
 365         help
 366           This option performs a series of startup tests on ftrace. On bootup
 367           a series of tests are made to verify that the tracer is
 368           functioning properly. It will do tests on all the configured
 369           tracers of ftrace.
 370
 371 config MMIOTRACE
 372         bool "Memory mapped IO tracing"
 373         depends on HAVE_MMIOTRACE_SUPPORT && DEBUG_KERNEL && PCI
 374         select TRACING
 375         help
 376           Mmiotrace traces Memory Mapped I/O access and is meant for
 377           debugging and reverse engineering. It is called from the ioremap
 378           implementation and works via page faults. Tracing is disabled by
 379           default and can be enabled at run-time.
 380
 381           See Documentation/tracers/mmiotrace.txt.
 382           If you are not helping to develop drivers, say N.
 383
 384 config MMIOTRACE_TEST
 385         tristate "Test module for mmiotrace"
 386         depends on MMIOTRACE && m
 387         help
 388           This is a dumb module for testing mmiotrace. It is very dangerous
 389           as it will write garbage to IO memory starting at a given address.
 390           However, it should be safe to use on e.g. unused portion of VRAM.
 391
 392           Say N, unless you absolutely know what you are doing.
 393
 394 endmenu