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Linux/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 CONTEXT_SWITCH_TRACER
 86         bool
 87 
 88 config RING_BUFFER_ALLOW_SWAP
 89         bool
 90         help
 91          Allow the use of ring_buffer_swap_cpu.
 92          Adds a very slight overhead to tracing when enabled.
 93 
 94 # All tracer options should select GENERIC_TRACER. For those options that are
 95 # enabled by all tracers (context switch and event tracer) they select TRACING.
 96 # This allows those options to appear when no other tracer is selected. But the
 97 # options do not appear when something else selects it. We need the two options
 98 # GENERIC_TRACER and TRACING to avoid circular dependencies to accomplish the
 99 # hiding of the automatic options.
100 
101 config TRACING
102         bool
103         select DEBUG_FS
104         select RING_BUFFER
105         select STACKTRACE if STACKTRACE_SUPPORT
106         select TRACEPOINTS
107         select NOP_TRACER
108         select BINARY_PRINTF
109         select EVENT_TRACING
110         select TRACE_CLOCK
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         depends on PERF_EVENTS
428         select UPROBES
429         select PROBE_EVENTS
430         select TRACING
431         default n
432         help
433           This allows the user to add tracing events on top of userspace
434           dynamic events (similar to tracepoints) on the fly via the trace
435           events interface. Those events can be inserted wherever uprobes
436           can probe, and record various registers.
437           This option is required if you plan to use perf-probe subcommand
438           of perf tools on user space applications.
439 
440 config PROBE_EVENTS
441         def_bool n
442 
443 config DYNAMIC_FTRACE
444         bool "enable/disable function tracing dynamically"
445         depends on FUNCTION_TRACER
446         depends on HAVE_DYNAMIC_FTRACE
447         default y
448         help
449           This option will modify all the calls to function tracing
450           dynamically (will patch them out of the binary image and
451           replace them with a No-Op instruction) on boot up. During
452           compile time, a table is made of all the locations that ftrace
453           can function trace, and this table is linked into the kernel
454           image. When this is enabled, functions can be individually
455           enabled, and the functions not enabled will not affect
456           performance of the system.
457 
458           See the files in /sys/kernel/debug/tracing:
459             available_filter_functions
460             set_ftrace_filter
461             set_ftrace_notrace
462 
463           This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but
464           otherwise has native performance as long as no tracing is active.
465 
466 config DYNAMIC_FTRACE_WITH_REGS
467         def_bool y
468         depends on DYNAMIC_FTRACE
469         depends on HAVE_DYNAMIC_FTRACE_WITH_REGS
470 
471 config FUNCTION_PROFILER
472         bool "Kernel function profiler"
473         depends on FUNCTION_TRACER
474         default n
475         help
476           This option enables the kernel function profiler. A file is created
477           in debugfs called function_profile_enabled which defaults to zero.
478           When a 1 is echoed into this file profiling begins, and when a
479           zero is entered, profiling stops. A "functions" file is created in
480           the trace_stats directory; this file shows the list of functions that
481           have been hit and their counters.
482 
483           If in doubt, say N.
484 
485 config FTRACE_MCOUNT_RECORD
486         def_bool y
487         depends on DYNAMIC_FTRACE
488         depends on HAVE_FTRACE_MCOUNT_RECORD
489 
490 config FTRACE_SELFTEST
491         bool
492 
493 config FTRACE_STARTUP_TEST
494         bool "Perform a startup test on ftrace"
495         depends on GENERIC_TRACER
496         select FTRACE_SELFTEST
497         help
498           This option performs a series of startup tests on ftrace. On bootup
499           a series of tests are made to verify that the tracer is
500           functioning properly. It will do tests on all the configured
501           tracers of ftrace.
502 
503 config EVENT_TRACE_TEST_SYSCALLS
504         bool "Run selftest on syscall events"
505         depends on FTRACE_STARTUP_TEST
506         help
507          This option will also enable testing every syscall event.
508          It only enables the event and disables it and runs various loads
509          with the event enabled. This adds a bit more time for kernel boot
510          up since it runs this on every system call defined.
511 
512          TBD - enable a way to actually call the syscalls as we test their
513                events
514 
515 config MMIOTRACE
516         bool "Memory mapped IO tracing"
517         depends on HAVE_MMIOTRACE_SUPPORT && PCI
518         select GENERIC_TRACER
519         help
520           Mmiotrace traces Memory Mapped I/O access and is meant for
521           debugging and reverse engineering. It is called from the ioremap
522           implementation and works via page faults. Tracing is disabled by
523           default and can be enabled at run-time.
524 
525           See Documentation/trace/mmiotrace.txt.
526           If you are not helping to develop drivers, say N.
527 
528 config MMIOTRACE_TEST
529         tristate "Test module for mmiotrace"
530         depends on MMIOTRACE && m
531         help
532           This is a dumb module for testing mmiotrace. It is very dangerous
533           as it will write garbage to IO memory starting at a given address.
534           However, it should be safe to use on e.g. unused portion of VRAM.
535 
536           Say N, unless you absolutely know what you are doing.
537 
538 config TRACEPOINT_BENCHMARK
539         bool "Add tracepoint that benchmarks tracepoints"
540         help
541          This option creates the tracepoint "benchmark:benchmark_event".
542          When the tracepoint is enabled, it kicks off a kernel thread that
543          goes into an infinite loop (calling cond_sched() to let other tasks
544          run), and calls the tracepoint. Each iteration will record the time
545          it took to write to the tracepoint and the next iteration that
546          data will be passed to the tracepoint itself. That is, the tracepoint
547          will report the time it took to do the previous tracepoint.
548          The string written to the tracepoint is a static string of 128 bytes
549          to keep the time the same. The initial string is simply a write of
550          "START". The second string records the cold cache time of the first
551          write which is not added to the rest of the calculations.
552 
553          As it is a tight loop, it benchmarks as hot cache. That's fine because
554          we care most about hot paths that are probably in cache already.
555 
556          An example of the output:
557 
558               START
559               first=3672 [COLD CACHED]
560               last=632 first=3672 max=632 min=632 avg=316 std=446 std^2=199712
561               last=278 first=3672 max=632 min=278 avg=303 std=316 std^2=100337
562               last=277 first=3672 max=632 min=277 avg=296 std=258 std^2=67064
563               last=273 first=3672 max=632 min=273 avg=292 std=224 std^2=50411
564               last=273 first=3672 max=632 min=273 avg=288 std=200 std^2=40389
565               last=281 first=3672 max=632 min=273 avg=287 std=183 std^2=33666
566 
567 
568 config RING_BUFFER_BENCHMARK
569         tristate "Ring buffer benchmark stress tester"
570         depends on RING_BUFFER
571         help
572           This option creates a test to stress the ring buffer and benchmark it.
573           It creates its own ring buffer such that it will not interfere with
574           any other users of the ring buffer (such as ftrace). It then creates
575           a producer and consumer that will run for 10 seconds and sleep for
576           10 seconds. Each interval it will print out the number of events
577           it recorded and give a rough estimate of how long each iteration took.
578 
579           It does not disable interrupts or raise its priority, so it may be
580           affected by processes that are running.
581 
582           If unsure, say N.
583 
584 config RING_BUFFER_STARTUP_TEST
585        bool "Ring buffer startup self test"
586        depends on RING_BUFFER
587        help
588          Run a simple self test on the ring buffer on boot up. Late in the
589          kernel boot sequence, the test will start that kicks off
590          a thread per cpu. Each thread will write various size events
591          into the ring buffer. Another thread is created to send IPIs
592          to each of the threads, where the IPI handler will also write
593          to the ring buffer, to test/stress the nesting ability.
594          If any anomalies are discovered, a warning will be displayed
595          and all ring buffers will be disabled.
596 
597          The test runs for 10 seconds. This will slow your boot time
598          by at least 10 more seconds.
599 
600          At the end of the test, statics and more checks are done.
601          It will output the stats of each per cpu buffer. What
602          was written, the sizes, what was read, what was lost, and
603          other similar details.
604 
605          If unsure, say N
606 
607 endif # FTRACE
608 
609 endif # TRACING_SUPPORT
610 

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