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1#
2# Architectures that offer an FUNCTION_TRACER implementation should
3# select HAVE_FUNCTION_TRACER:
4#
5
6config USER_STACKTRACE_SUPPORT
7 bool
8
9config NOP_TRACER
10 bool
11
12config HAVE_FTRACE_NMI_ENTER
13 bool
14 help
15 See Documentation/trace/ftrace-design.txt
16
17config HAVE_FUNCTION_TRACER
18 bool
19 help
20 See Documentation/trace/ftrace-design.txt
21
22config HAVE_FUNCTION_GRAPH_TRACER
23 bool
24 help
25 See Documentation/trace/ftrace-design.txt
26
27config HAVE_DYNAMIC_FTRACE
28 bool
29 help
30 See Documentation/trace/ftrace-design.txt
31
32config HAVE_DYNAMIC_FTRACE_WITH_REGS
33 bool
34
35config HAVE_FTRACE_MCOUNT_RECORD
36 bool
37 help
38 See Documentation/trace/ftrace-design.txt
39
40config HAVE_SYSCALL_TRACEPOINTS
41 bool
42 help
43 See Documentation/trace/ftrace-design.txt
44
45config HAVE_FENTRY
46 bool
47 help
48 Arch supports the gcc options -pg with -mfentry
49
50config HAVE_C_RECORDMCOUNT
51 bool
52 help
53 C version of recordmcount available?
54
55config TRACER_MAX_TRACE
56 bool
57
58config TRACE_CLOCK
59 bool
60
61config RING_BUFFER
62 bool
63 select TRACE_CLOCK
64 select IRQ_WORK
65
66config FTRACE_NMI_ENTER
67 bool
68 depends on HAVE_FTRACE_NMI_ENTER
69 default y
70
71config EVENT_TRACING
72 select CONTEXT_SWITCH_TRACER
73 select GLOB
74 bool
75
76config CONTEXT_SWITCH_TRACER
77 bool
78
79config RING_BUFFER_ALLOW_SWAP
80 bool
81 help
82 Allow the use of ring_buffer_swap_cpu.
83 Adds a very slight overhead to tracing when enabled.
84
85# All tracer options should select GENERIC_TRACER. For those options that are
86# enabled by all tracers (context switch and event tracer) they select TRACING.
87# This allows those options to appear when no other tracer is selected. But the
88# options do not appear when something else selects it. We need the two options
89# GENERIC_TRACER and TRACING to avoid circular dependencies to accomplish the
90# hiding of the automatic options.
91
92config TRACING
93 bool
94 select DEBUG_FS
95 select RING_BUFFER
96 select STACKTRACE if STACKTRACE_SUPPORT
97 select TRACEPOINTS
98 select NOP_TRACER
99 select BINARY_PRINTF
100 select EVENT_TRACING
101 select TRACE_CLOCK
102
103config GENERIC_TRACER
104 bool
105 select TRACING
106
107#
108# Minimum requirements an architecture has to meet for us to
109# be able to offer generic tracing facilities:
110#
111config TRACING_SUPPORT
112 bool
113 # PPC32 has no irqflags tracing support, but it can use most of the
114 # tracers anyway, they were tested to build and work. Note that new
115 # exceptions to this list aren't welcomed, better implement the
116 # irqflags tracing for your architecture.
117 depends on TRACE_IRQFLAGS_SUPPORT || PPC32
118 depends on STACKTRACE_SUPPORT
119 default y
120
121if TRACING_SUPPORT
122
123menuconfig FTRACE
124 bool "Tracers"
125 default y if DEBUG_KERNEL
126 help
127 Enable the kernel tracing infrastructure.
128
129if FTRACE
130
131config FUNCTION_TRACER
132 bool "Kernel Function Tracer"
133 depends on HAVE_FUNCTION_TRACER
134 select KALLSYMS
135 select GENERIC_TRACER
136 select CONTEXT_SWITCH_TRACER
137 select GLOB
138 help
139 Enable the kernel to trace every kernel function. This is done
140 by using a compiler feature to insert a small, 5-byte No-Operation
141 instruction at the beginning of every kernel function, which NOP
142 sequence is then dynamically patched into a tracer call when
143 tracing is enabled by the administrator. If it's runtime disabled
144 (the bootup default), then the overhead of the instructions is very
145 small and not measurable even in micro-benchmarks.
146
147config FUNCTION_GRAPH_TRACER
148 bool "Kernel Function Graph Tracer"
149 depends on HAVE_FUNCTION_GRAPH_TRACER
150 depends on FUNCTION_TRACER
151 depends on !X86_32 || !CC_OPTIMIZE_FOR_SIZE
152 default y
153 help
154 Enable the kernel to trace a function at both its return
155 and its entry.
156 Its first purpose is to trace the duration of functions and
157 draw a call graph for each thread with some information like
158 the return value. This is done by setting the current return
159 address on the current task structure into a stack of calls.
160
161
162config IRQSOFF_TRACER
163 bool "Interrupts-off Latency Tracer"
164 default n
165 depends on TRACE_IRQFLAGS_SUPPORT
166 depends on !ARCH_USES_GETTIMEOFFSET
167 select TRACE_IRQFLAGS
168 select GENERIC_TRACER
169 select TRACER_MAX_TRACE
170 select RING_BUFFER_ALLOW_SWAP
171 select TRACER_SNAPSHOT
172 select TRACER_SNAPSHOT_PER_CPU_SWAP
173 help
174 This option measures the time spent in irqs-off critical
175 sections, with microsecond accuracy.
176
177 The default measurement method is a maximum search, which is
178 disabled by default and can be runtime (re-)started
179 via:
180
181 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
182
183 (Note that kernel size and overhead increase with this option
184 enabled. This option and the preempt-off timing option can be
185 used together or separately.)
186
187config PREEMPT_TRACER
188 bool "Preemption-off Latency Tracer"
189 default n
190 depends on !ARCH_USES_GETTIMEOFFSET
191 depends on PREEMPT
192 select GENERIC_TRACER
193 select TRACER_MAX_TRACE
194 select RING_BUFFER_ALLOW_SWAP
195 select TRACER_SNAPSHOT
196 select TRACER_SNAPSHOT_PER_CPU_SWAP
197 help
198 This option measures the time spent in preemption-off critical
199 sections, with microsecond accuracy.
200
201 The default measurement method is a maximum search, which is
202 disabled by default and can be runtime (re-)started
203 via:
204
205 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
206
207 (Note that kernel size and overhead increase with this option
208 enabled. This option and the irqs-off timing option can be
209 used together or separately.)
210
211config SCHED_TRACER
212 bool "Scheduling Latency Tracer"
213 select GENERIC_TRACER
214 select CONTEXT_SWITCH_TRACER
215 select TRACER_MAX_TRACE
216 select TRACER_SNAPSHOT
217 help
218 This tracer tracks the latency of the highest priority task
219 to be scheduled in, starting from the point it has woken up.
220
221config HWLAT_TRACER
222 bool "Tracer to detect hardware latencies (like SMIs)"
223 select GENERIC_TRACER
224 help
225 This tracer, when enabled will create one or more kernel threads,
226 depening on what the cpumask file is set to, which each thread
227 spinning in a loop looking for interruptions caused by
228 something other than the kernel. For example, if a
229 System Management Interrupt (SMI) takes a noticeable amount of
230 time, this tracer will detect it. This is useful for testing
231 if a system is reliable for Real Time tasks.
232
233 Some files are created in the tracing directory when this
234 is enabled:
235
236 hwlat_detector/width - time in usecs for how long to spin for
237 hwlat_detector/window - time in usecs between the start of each
238 iteration
239
240 A kernel thread is created that will spin with interrupts disabled
241 for "width" microseconds in every "widow" cycle. It will not spin
242 for "window - width" microseconds, where the system can
243 continue to operate.
244
245 The output will appear in the trace and trace_pipe files.
246
247 When the tracer is not running, it has no affect on the system,
248 but when it is running, it can cause the system to be
249 periodically non responsive. Do not run this tracer on a
250 production system.
251
252 To enable this tracer, echo in "hwlat" into the current_tracer
253 file. Every time a latency is greater than tracing_thresh, it will
254 be recorded into the ring buffer.
255
256config ENABLE_DEFAULT_TRACERS
257 bool "Trace process context switches and events"
258 depends on !GENERIC_TRACER
259 select TRACING
260 help
261 This tracer hooks to various trace points in the kernel,
262 allowing the user to pick and choose which trace point they
263 want to trace. It also includes the sched_switch tracer plugin.
264
265config FTRACE_SYSCALLS
266 bool "Trace syscalls"
267 depends on HAVE_SYSCALL_TRACEPOINTS
268 select GENERIC_TRACER
269 select KALLSYMS
270 help
271 Basic tracer to catch the syscall entry and exit events.
272
273config TRACER_SNAPSHOT
274 bool "Create a snapshot trace buffer"
275 select TRACER_MAX_TRACE
276 help
277 Allow tracing users to take snapshot of the current buffer using the
278 ftrace interface, e.g.:
279
280 echo 1 > /sys/kernel/debug/tracing/snapshot
281 cat snapshot
282
283config TRACER_SNAPSHOT_PER_CPU_SWAP
284 bool "Allow snapshot to swap per CPU"
285 depends on TRACER_SNAPSHOT
286 select RING_BUFFER_ALLOW_SWAP
287 help
288 Allow doing a snapshot of a single CPU buffer instead of a
289 full swap (all buffers). If this is set, then the following is
290 allowed:
291
292 echo 1 > /sys/kernel/debug/tracing/per_cpu/cpu2/snapshot
293
294 After which, only the tracing buffer for CPU 2 was swapped with
295 the main tracing buffer, and the other CPU buffers remain the same.
296
297 When this is enabled, this adds a little more overhead to the
298 trace recording, as it needs to add some checks to synchronize
299 recording with swaps. But this does not affect the performance
300 of the overall system. This is enabled by default when the preempt
301 or irq latency tracers are enabled, as those need to swap as well
302 and already adds the overhead (plus a lot more).
303
304config TRACE_BRANCH_PROFILING
305 bool
306 select GENERIC_TRACER
307
308choice
309 prompt "Branch Profiling"
310 default BRANCH_PROFILE_NONE
311 help
312 The branch profiling is a software profiler. It will add hooks
313 into the C conditionals to test which path a branch takes.
314
315 The likely/unlikely profiler only looks at the conditions that
316 are annotated with a likely or unlikely macro.
317
318 The "all branch" profiler will profile every if-statement in the
319 kernel. This profiler will also enable the likely/unlikely
320 profiler.
321
322 Either of the above profilers adds a bit of overhead to the system.
323 If unsure, choose "No branch profiling".
324
325config BRANCH_PROFILE_NONE
326 bool "No branch profiling"
327 help
328 No branch profiling. Branch profiling adds a bit of overhead.
329 Only enable it if you want to analyse the branching behavior.
330 Otherwise keep it disabled.
331
332config PROFILE_ANNOTATED_BRANCHES
333 bool "Trace likely/unlikely profiler"
334 select TRACE_BRANCH_PROFILING
335 help
336 This tracer profiles all likely and unlikely macros
337 in the kernel. It will display the results in:
338
339 /sys/kernel/debug/tracing/trace_stat/branch_annotated
340
341 Note: this will add a significant overhead; only turn this
342 on if you need to profile the system's use of these macros.
343
344config PROFILE_ALL_BRANCHES
345 bool "Profile all if conditionals"
346 select TRACE_BRANCH_PROFILING
347 help
348 This tracer profiles all branch conditions. Every if ()
349 taken in the kernel is recorded whether it hit or miss.
350 The results will be displayed in:
351
352 /sys/kernel/debug/tracing/trace_stat/branch_all
353
354 This option also enables the likely/unlikely profiler.
355
356 This configuration, when enabled, will impose a great overhead
357 on the system. This should only be enabled when the system
358 is to be analyzed in much detail.
359endchoice
360
361config TRACING_BRANCHES
362 bool
363 help
364 Selected by tracers that will trace the likely and unlikely
365 conditions. This prevents the tracers themselves from being
366 profiled. Profiling the tracing infrastructure can only happen
367 when the likelys and unlikelys are not being traced.
368
369config BRANCH_TRACER
370 bool "Trace likely/unlikely instances"
371 depends on TRACE_BRANCH_PROFILING
372 select TRACING_BRANCHES
373 help
374 This traces the events of likely and unlikely condition
375 calls in the kernel. The difference between this and the
376 "Trace likely/unlikely profiler" is that this is not a
377 histogram of the callers, but actually places the calling
378 events into a running trace buffer to see when and where the
379 events happened, as well as their results.
380
381 Say N if unsure.
382
383config STACK_TRACER
384 bool "Trace max stack"
385 depends on HAVE_FUNCTION_TRACER
386 select FUNCTION_TRACER
387 select STACKTRACE
388 select KALLSYMS
389 help
390 This special tracer records the maximum stack footprint of the
391 kernel and displays it in /sys/kernel/debug/tracing/stack_trace.
392
393 This tracer works by hooking into every function call that the
394 kernel executes, and keeping a maximum stack depth value and
395 stack-trace saved. If this is configured with DYNAMIC_FTRACE
396 then it will not have any overhead while the stack tracer
397 is disabled.
398
399 To enable the stack tracer on bootup, pass in 'stacktrace'
400 on the kernel command line.
401
402 The stack tracer can also be enabled or disabled via the
403 sysctl kernel.stack_tracer_enabled
404
405 Say N if unsure.
406
407config BLK_DEV_IO_TRACE
408 bool "Support for tracing block IO actions"
409 depends on SYSFS
410 depends on BLOCK
411 select RELAY
412 select DEBUG_FS
413 select TRACEPOINTS
414 select GENERIC_TRACER
415 select STACKTRACE
416 help
417 Say Y here if you want to be able to trace the block layer actions
418 on a given queue. Tracing allows you to see any traffic happening
419 on a block device queue. For more information (and the userspace
420 support tools needed), fetch the blktrace tools from:
421
422 git://git.kernel.dk/blktrace.git
423
424 Tracing also is possible using the ftrace interface, e.g.:
425
426 echo 1 > /sys/block/sda/sda1/trace/enable
427 echo blk > /sys/kernel/debug/tracing/current_tracer
428 cat /sys/kernel/debug/tracing/trace_pipe
429
430 If unsure, say N.
431
432config KPROBE_EVENT
433 depends on KPROBES
434 depends on HAVE_REGS_AND_STACK_ACCESS_API
435 bool "Enable kprobes-based dynamic events"
436 select TRACING
437 select PROBE_EVENTS
438 default y
439 help
440 This allows the user to add tracing events (similar to tracepoints)
441 on the fly via the ftrace interface. See
442 Documentation/trace/kprobetrace.txt for more details.
443
444 Those events can be inserted wherever kprobes can probe, and record
445 various register and memory values.
446
447 This option is also required by perf-probe subcommand of perf tools.
448 If you want to use perf tools, this option is strongly recommended.
449
450config UPROBE_EVENT
451 bool "Enable uprobes-based dynamic events"
452 depends on ARCH_SUPPORTS_UPROBES
453 depends on MMU
454 depends on PERF_EVENTS
455 select UPROBES
456 select PROBE_EVENTS
457 select TRACING
458 default n
459 help
460 This allows the user to add tracing events on top of userspace
461 dynamic events (similar to tracepoints) on the fly via the trace
462 events interface. Those events can be inserted wherever uprobes
463 can probe, and record various registers.
464 This option is required if you plan to use perf-probe subcommand
465 of perf tools on user space applications.
466
467config BPF_EVENTS
468 depends on BPF_SYSCALL
469 depends on (KPROBE_EVENT || UPROBE_EVENT) && PERF_EVENTS
470 bool
471 default y
472 help
473 This allows the user to attach BPF programs to kprobe events.
474
475config PROBE_EVENTS
476 def_bool n
477
478config DYNAMIC_FTRACE
479 bool "enable/disable function tracing dynamically"
480 depends on FUNCTION_TRACER
481 depends on HAVE_DYNAMIC_FTRACE
482 default y
483 help
484 This option will modify all the calls to function tracing
485 dynamically (will patch them out of the binary image and
486 replace them with a No-Op instruction) on boot up. During
487 compile time, a table is made of all the locations that ftrace
488 can function trace, and this table is linked into the kernel
489 image. When this is enabled, functions can be individually
490 enabled, and the functions not enabled will not affect
491 performance of the system.
492
493 See the files in /sys/kernel/debug/tracing:
494 available_filter_functions
495 set_ftrace_filter
496 set_ftrace_notrace
497
498 This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but
499 otherwise has native performance as long as no tracing is active.
500
501config DYNAMIC_FTRACE_WITH_REGS
502 def_bool y
503 depends on DYNAMIC_FTRACE
504 depends on HAVE_DYNAMIC_FTRACE_WITH_REGS
505
506config FUNCTION_PROFILER
507 bool "Kernel function profiler"
508 depends on FUNCTION_TRACER
509 default n
510 help
511 This option enables the kernel function profiler. A file is created
512 in debugfs called function_profile_enabled which defaults to zero.
513 When a 1 is echoed into this file profiling begins, and when a
514 zero is entered, profiling stops. A "functions" file is created in
515 the trace_stats directory; this file shows the list of functions that
516 have been hit and their counters.
517
518 If in doubt, say N.
519
520config FTRACE_MCOUNT_RECORD
521 def_bool y
522 depends on DYNAMIC_FTRACE
523 depends on HAVE_FTRACE_MCOUNT_RECORD
524
525config FTRACE_SELFTEST
526 bool
527
528config FTRACE_STARTUP_TEST
529 bool "Perform a startup test on ftrace"
530 depends on GENERIC_TRACER
531 select FTRACE_SELFTEST
532 help
533 This option performs a series of startup tests on ftrace. On bootup
534 a series of tests are made to verify that the tracer is
535 functioning properly. It will do tests on all the configured
536 tracers of ftrace.
537
538config EVENT_TRACE_TEST_SYSCALLS
539 bool "Run selftest on syscall events"
540 depends on FTRACE_STARTUP_TEST
541 help
542 This option will also enable testing every syscall event.
543 It only enables the event and disables it and runs various loads
544 with the event enabled. This adds a bit more time for kernel boot
545 up since it runs this on every system call defined.
546
547 TBD - enable a way to actually call the syscalls as we test their
548 events
549
550config MMIOTRACE
551 bool "Memory mapped IO tracing"
552 depends on HAVE_MMIOTRACE_SUPPORT && PCI
553 select GENERIC_TRACER
554 help
555 Mmiotrace traces Memory Mapped I/O access and is meant for
556 debugging and reverse engineering. It is called from the ioremap
557 implementation and works via page faults. Tracing is disabled by
558 default and can be enabled at run-time.
559
560 See Documentation/trace/mmiotrace.txt.
561 If you are not helping to develop drivers, say N.
562
563config TRACING_MAP
564 bool
565 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
566 help
567 tracing_map is a special-purpose lock-free map for tracing,
568 separated out as a stand-alone facility in order to allow it
569 to be shared between multiple tracers. It isn't meant to be
570 generally used outside of that context, and is normally
571 selected by tracers that use it.
572
573config HIST_TRIGGERS
574 bool "Histogram triggers"
575 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
576 select TRACING_MAP
577 select TRACING
578 default n
579 help
580 Hist triggers allow one or more arbitrary trace event fields
581 to be aggregated into hash tables and dumped to stdout by
582 reading a debugfs/tracefs file. They're useful for
583 gathering quick and dirty (though precise) summaries of
584 event activity as an initial guide for further investigation
585 using more advanced tools.
586
587 See Documentation/trace/events.txt.
588 If in doubt, say N.
589
590config MMIOTRACE_TEST
591 tristate "Test module for mmiotrace"
592 depends on MMIOTRACE && m
593 help
594 This is a dumb module for testing mmiotrace. It is very dangerous
595 as it will write garbage to IO memory starting at a given address.
596 However, it should be safe to use on e.g. unused portion of VRAM.
597
598 Say N, unless you absolutely know what you are doing.
599
600config TRACEPOINT_BENCHMARK
601 bool "Add tracepoint that benchmarks tracepoints"
602 help
603 This option creates the tracepoint "benchmark:benchmark_event".
604 When the tracepoint is enabled, it kicks off a kernel thread that
605 goes into an infinite loop (calling cond_sched() to let other tasks
606 run), and calls the tracepoint. Each iteration will record the time
607 it took to write to the tracepoint and the next iteration that
608 data will be passed to the tracepoint itself. That is, the tracepoint
609 will report the time it took to do the previous tracepoint.
610 The string written to the tracepoint is a static string of 128 bytes
611 to keep the time the same. The initial string is simply a write of
612 "START". The second string records the cold cache time of the first
613 write which is not added to the rest of the calculations.
614
615 As it is a tight loop, it benchmarks as hot cache. That's fine because
616 we care most about hot paths that are probably in cache already.
617
618 An example of the output:
619
620 START
621 first=3672 [COLD CACHED]
622 last=632 first=3672 max=632 min=632 avg=316 std=446 std^2=199712
623 last=278 first=3672 max=632 min=278 avg=303 std=316 std^2=100337
624 last=277 first=3672 max=632 min=277 avg=296 std=258 std^2=67064
625 last=273 first=3672 max=632 min=273 avg=292 std=224 std^2=50411
626 last=273 first=3672 max=632 min=273 avg=288 std=200 std^2=40389
627 last=281 first=3672 max=632 min=273 avg=287 std=183 std^2=33666
628
629
630config RING_BUFFER_BENCHMARK
631 tristate "Ring buffer benchmark stress tester"
632 depends on RING_BUFFER
633 help
634 This option creates a test to stress the ring buffer and benchmark it.
635 It creates its own ring buffer such that it will not interfere with
636 any other users of the ring buffer (such as ftrace). It then creates
637 a producer and consumer that will run for 10 seconds and sleep for
638 10 seconds. Each interval it will print out the number of events
639 it recorded and give a rough estimate of how long each iteration took.
640
641 It does not disable interrupts or raise its priority, so it may be
642 affected by processes that are running.
643
644 If unsure, say N.
645
646config RING_BUFFER_STARTUP_TEST
647 bool "Ring buffer startup self test"
648 depends on RING_BUFFER
649 help
650 Run a simple self test on the ring buffer on boot up. Late in the
651 kernel boot sequence, the test will start that kicks off
652 a thread per cpu. Each thread will write various size events
653 into the ring buffer. Another thread is created to send IPIs
654 to each of the threads, where the IPI handler will also write
655 to the ring buffer, to test/stress the nesting ability.
656 If any anomalies are discovered, a warning will be displayed
657 and all ring buffers will be disabled.
658
659 The test runs for 10 seconds. This will slow your boot time
660 by at least 10 more seconds.
661
662 At the end of the test, statics and more checks are done.
663 It will output the stats of each per cpu buffer. What
664 was written, the sizes, what was read, what was lost, and
665 other similar details.
666
667 If unsure, say N
668
669config TRACE_ENUM_MAP_FILE
670 bool "Show enum mappings for trace events"
671 depends on TRACING
672 help
673 The "print fmt" of the trace events will show the enum names instead
674 of their values. This can cause problems for user space tools that
675 use this string to parse the raw data as user space does not know
676 how to convert the string to its value.
677
678 To fix this, there's a special macro in the kernel that can be used
679 to convert the enum into its value. If this macro is used, then the
680 print fmt strings will have the enums converted to their values.
681
682 If something does not get converted properly, this option can be
683 used to show what enums the kernel tried to convert.
684
685 This option is for debugging the enum conversions. A file is created
686 in the tracing directory called "enum_map" that will show the enum
687 names matched with their values and what trace event system they
688 belong too.
689
690 Normally, the mapping of the strings to values will be freed after
691 boot up or module load. With this option, they will not be freed, as
692 they are needed for the "enum_map" file. Enabling this option will
693 increase the memory footprint of the running kernel.
694
695 If unsure, say N
696
697config TRACING_EVENTS_GPIO
698 bool "Trace gpio events"
699 depends on GPIOLIB
700 default y
701 help
702 Enable tracing events for gpio subsystem
703
704endif # FTRACE
705
706endif # TRACING_SUPPORT
707
1# SPDX-License-Identifier: GPL-2.0-only
2#
3# Architectures that offer an FUNCTION_TRACER implementation should
4# select HAVE_FUNCTION_TRACER:
5#
6
7config USER_STACKTRACE_SUPPORT
8 bool
9
10config NOP_TRACER
11 bool
12
13config HAVE_FUNCTION_TRACER
14 bool
15 help
16 See Documentation/trace/ftrace-design.rst
17
18config HAVE_FUNCTION_GRAPH_TRACER
19 bool
20 help
21 See Documentation/trace/ftrace-design.rst
22
23config HAVE_DYNAMIC_FTRACE
24 bool
25 help
26 See Documentation/trace/ftrace-design.rst
27
28config HAVE_DYNAMIC_FTRACE_WITH_REGS
29 bool
30
31config HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
32 bool
33
34config HAVE_DYNAMIC_FTRACE_WITH_ARGS
35 bool
36 help
37 If this is set, then arguments and stack can be found from
38 the pt_regs passed into the function callback regs parameter
39 by default, even without setting the REGS flag in the ftrace_ops.
40 This allows for use of regs_get_kernel_argument() and
41 kernel_stack_pointer().
42
43config HAVE_FTRACE_MCOUNT_RECORD
44 bool
45 help
46 See Documentation/trace/ftrace-design.rst
47
48config HAVE_SYSCALL_TRACEPOINTS
49 bool
50 help
51 See Documentation/trace/ftrace-design.rst
52
53config HAVE_FENTRY
54 bool
55 help
56 Arch supports the gcc options -pg with -mfentry
57
58config HAVE_NOP_MCOUNT
59 bool
60 help
61 Arch supports the gcc options -pg with -mrecord-mcount and -nop-mcount
62
63config HAVE_OBJTOOL_MCOUNT
64 bool
65 help
66 Arch supports objtool --mcount
67
68config HAVE_C_RECORDMCOUNT
69 bool
70 help
71 C version of recordmcount available?
72
73config TRACER_MAX_TRACE
74 bool
75
76config TRACE_CLOCK
77 bool
78
79config RING_BUFFER
80 bool
81 select TRACE_CLOCK
82 select IRQ_WORK
83
84config EVENT_TRACING
85 select CONTEXT_SWITCH_TRACER
86 select GLOB
87 bool
88
89config CONTEXT_SWITCH_TRACER
90 bool
91
92config RING_BUFFER_ALLOW_SWAP
93 bool
94 help
95 Allow the use of ring_buffer_swap_cpu.
96 Adds a very slight overhead to tracing when enabled.
97
98config PREEMPTIRQ_TRACEPOINTS
99 bool
100 depends on TRACE_PREEMPT_TOGGLE || TRACE_IRQFLAGS
101 select TRACING
102 default y
103 help
104 Create preempt/irq toggle tracepoints if needed, so that other parts
105 of the kernel can use them to generate or add hooks to them.
106
107# All tracer options should select GENERIC_TRACER. For those options that are
108# enabled by all tracers (context switch and event tracer) they select TRACING.
109# This allows those options to appear when no other tracer is selected. But the
110# options do not appear when something else selects it. We need the two options
111# GENERIC_TRACER and TRACING to avoid circular dependencies to accomplish the
112# hiding of the automatic options.
113
114config TRACING
115 bool
116 select RING_BUFFER
117 select STACKTRACE if STACKTRACE_SUPPORT
118 select TRACEPOINTS
119 select NOP_TRACER
120 select BINARY_PRINTF
121 select EVENT_TRACING
122 select TRACE_CLOCK
123
124config GENERIC_TRACER
125 bool
126 select TRACING
127
128#
129# Minimum requirements an architecture has to meet for us to
130# be able to offer generic tracing facilities:
131#
132config TRACING_SUPPORT
133 bool
134 depends on TRACE_IRQFLAGS_SUPPORT
135 depends on STACKTRACE_SUPPORT
136 default y
137
138if TRACING_SUPPORT
139
140menuconfig FTRACE
141 bool "Tracers"
142 default y if DEBUG_KERNEL
143 help
144 Enable the kernel tracing infrastructure.
145
146if FTRACE
147
148config BOOTTIME_TRACING
149 bool "Boot-time Tracing support"
150 depends on TRACING
151 select BOOT_CONFIG
152 help
153 Enable developer to setup ftrace subsystem via supplemental
154 kernel cmdline at boot time for debugging (tracing) driver
155 initialization and boot process.
156
157config FUNCTION_TRACER
158 bool "Kernel Function Tracer"
159 depends on HAVE_FUNCTION_TRACER
160 select KALLSYMS
161 select GENERIC_TRACER
162 select CONTEXT_SWITCH_TRACER
163 select GLOB
164 select TASKS_RCU if PREEMPTION
165 select TASKS_RUDE_RCU
166 help
167 Enable the kernel to trace every kernel function. This is done
168 by using a compiler feature to insert a small, 5-byte No-Operation
169 instruction at the beginning of every kernel function, which NOP
170 sequence is then dynamically patched into a tracer call when
171 tracing is enabled by the administrator. If it's runtime disabled
172 (the bootup default), then the overhead of the instructions is very
173 small and not measurable even in micro-benchmarks.
174
175config FUNCTION_GRAPH_TRACER
176 bool "Kernel Function Graph Tracer"
177 depends on HAVE_FUNCTION_GRAPH_TRACER
178 depends on FUNCTION_TRACER
179 depends on !X86_32 || !CC_OPTIMIZE_FOR_SIZE
180 default y
181 help
182 Enable the kernel to trace a function at both its return
183 and its entry.
184 Its first purpose is to trace the duration of functions and
185 draw a call graph for each thread with some information like
186 the return value. This is done by setting the current return
187 address on the current task structure into a stack of calls.
188
189config DYNAMIC_FTRACE
190 bool "enable/disable function tracing dynamically"
191 depends on FUNCTION_TRACER
192 depends on HAVE_DYNAMIC_FTRACE
193 default y
194 help
195 This option will modify all the calls to function tracing
196 dynamically (will patch them out of the binary image and
197 replace them with a No-Op instruction) on boot up. During
198 compile time, a table is made of all the locations that ftrace
199 can function trace, and this table is linked into the kernel
200 image. When this is enabled, functions can be individually
201 enabled, and the functions not enabled will not affect
202 performance of the system.
203
204 See the files in /sys/kernel/debug/tracing:
205 available_filter_functions
206 set_ftrace_filter
207 set_ftrace_notrace
208
209 This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but
210 otherwise has native performance as long as no tracing is active.
211
212config DYNAMIC_FTRACE_WITH_REGS
213 def_bool y
214 depends on DYNAMIC_FTRACE
215 depends on HAVE_DYNAMIC_FTRACE_WITH_REGS
216
217config DYNAMIC_FTRACE_WITH_DIRECT_CALLS
218 def_bool y
219 depends on DYNAMIC_FTRACE_WITH_REGS
220 depends on HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
221
222config DYNAMIC_FTRACE_WITH_ARGS
223 def_bool y
224 depends on DYNAMIC_FTRACE
225 depends on HAVE_DYNAMIC_FTRACE_WITH_ARGS
226
227config FUNCTION_PROFILER
228 bool "Kernel function profiler"
229 depends on FUNCTION_TRACER
230 default n
231 help
232 This option enables the kernel function profiler. A file is created
233 in debugfs called function_profile_enabled which defaults to zero.
234 When a 1 is echoed into this file profiling begins, and when a
235 zero is entered, profiling stops. A "functions" file is created in
236 the trace_stat directory; this file shows the list of functions that
237 have been hit and their counters.
238
239 If in doubt, say N.
240
241config STACK_TRACER
242 bool "Trace max stack"
243 depends on HAVE_FUNCTION_TRACER
244 select FUNCTION_TRACER
245 select STACKTRACE
246 select KALLSYMS
247 help
248 This special tracer records the maximum stack footprint of the
249 kernel and displays it in /sys/kernel/debug/tracing/stack_trace.
250
251 This tracer works by hooking into every function call that the
252 kernel executes, and keeping a maximum stack depth value and
253 stack-trace saved. If this is configured with DYNAMIC_FTRACE
254 then it will not have any overhead while the stack tracer
255 is disabled.
256
257 To enable the stack tracer on bootup, pass in 'stacktrace'
258 on the kernel command line.
259
260 The stack tracer can also be enabled or disabled via the
261 sysctl kernel.stack_tracer_enabled
262
263 Say N if unsure.
264
265config TRACE_PREEMPT_TOGGLE
266 bool
267 help
268 Enables hooks which will be called when preemption is first disabled,
269 and last enabled.
270
271config IRQSOFF_TRACER
272 bool "Interrupts-off Latency Tracer"
273 default n
274 depends on TRACE_IRQFLAGS_SUPPORT
275 select TRACE_IRQFLAGS
276 select GENERIC_TRACER
277 select TRACER_MAX_TRACE
278 select RING_BUFFER_ALLOW_SWAP
279 select TRACER_SNAPSHOT
280 select TRACER_SNAPSHOT_PER_CPU_SWAP
281 help
282 This option measures the time spent in irqs-off critical
283 sections, with microsecond accuracy.
284
285 The default measurement method is a maximum search, which is
286 disabled by default and can be runtime (re-)started
287 via:
288
289 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
290
291 (Note that kernel size and overhead increase with this option
292 enabled. This option and the preempt-off timing option can be
293 used together or separately.)
294
295config PREEMPT_TRACER
296 bool "Preemption-off Latency Tracer"
297 default n
298 depends on PREEMPTION
299 select GENERIC_TRACER
300 select TRACER_MAX_TRACE
301 select RING_BUFFER_ALLOW_SWAP
302 select TRACER_SNAPSHOT
303 select TRACER_SNAPSHOT_PER_CPU_SWAP
304 select TRACE_PREEMPT_TOGGLE
305 help
306 This option measures the time spent in preemption-off critical
307 sections, with microsecond accuracy.
308
309 The default measurement method is a maximum search, which is
310 disabled by default and can be runtime (re-)started
311 via:
312
313 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
314
315 (Note that kernel size and overhead increase with this option
316 enabled. This option and the irqs-off timing option can be
317 used together or separately.)
318
319config SCHED_TRACER
320 bool "Scheduling Latency Tracer"
321 select GENERIC_TRACER
322 select CONTEXT_SWITCH_TRACER
323 select TRACER_MAX_TRACE
324 select TRACER_SNAPSHOT
325 help
326 This tracer tracks the latency of the highest priority task
327 to be scheduled in, starting from the point it has woken up.
328
329config HWLAT_TRACER
330 bool "Tracer to detect hardware latencies (like SMIs)"
331 select GENERIC_TRACER
332 help
333 This tracer, when enabled will create one or more kernel threads,
334 depending on what the cpumask file is set to, which each thread
335 spinning in a loop looking for interruptions caused by
336 something other than the kernel. For example, if a
337 System Management Interrupt (SMI) takes a noticeable amount of
338 time, this tracer will detect it. This is useful for testing
339 if a system is reliable for Real Time tasks.
340
341 Some files are created in the tracing directory when this
342 is enabled:
343
344 hwlat_detector/width - time in usecs for how long to spin for
345 hwlat_detector/window - time in usecs between the start of each
346 iteration
347
348 A kernel thread is created that will spin with interrupts disabled
349 for "width" microseconds in every "window" cycle. It will not spin
350 for "window - width" microseconds, where the system can
351 continue to operate.
352
353 The output will appear in the trace and trace_pipe files.
354
355 When the tracer is not running, it has no affect on the system,
356 but when it is running, it can cause the system to be
357 periodically non responsive. Do not run this tracer on a
358 production system.
359
360 To enable this tracer, echo in "hwlat" into the current_tracer
361 file. Every time a latency is greater than tracing_thresh, it will
362 be recorded into the ring buffer.
363
364config OSNOISE_TRACER
365 bool "OS Noise tracer"
366 select GENERIC_TRACER
367 help
368 In the context of high-performance computing (HPC), the Operating
369 System Noise (osnoise) refers to the interference experienced by an
370 application due to activities inside the operating system. In the
371 context of Linux, NMIs, IRQs, SoftIRQs, and any other system thread
372 can cause noise to the system. Moreover, hardware-related jobs can
373 also cause noise, for example, via SMIs.
374
375 The osnoise tracer leverages the hwlat_detector by running a similar
376 loop with preemption, SoftIRQs and IRQs enabled, thus allowing all
377 the sources of osnoise during its execution. The osnoise tracer takes
378 note of the entry and exit point of any source of interferences,
379 increasing a per-cpu interference counter. It saves an interference
380 counter for each source of interference. The interference counter for
381 NMI, IRQs, SoftIRQs, and threads is increased anytime the tool
382 observes these interferences' entry events. When a noise happens
383 without any interference from the operating system level, the
384 hardware noise counter increases, pointing to a hardware-related
385 noise. In this way, osnoise can account for any source of
386 interference. At the end of the period, the osnoise tracer prints
387 the sum of all noise, the max single noise, the percentage of CPU
388 available for the thread, and the counters for the noise sources.
389
390 In addition to the tracer, a set of tracepoints were added to
391 facilitate the identification of the osnoise source.
392
393 The output will appear in the trace and trace_pipe files.
394
395 To enable this tracer, echo in "osnoise" into the current_tracer
396 file.
397
398config TIMERLAT_TRACER
399 bool "Timerlat tracer"
400 select OSNOISE_TRACER
401 select GENERIC_TRACER
402 help
403 The timerlat tracer aims to help the preemptive kernel developers
404 to find sources of wakeup latencies of real-time threads.
405
406 The tracer creates a per-cpu kernel thread with real-time priority.
407 The tracer thread sets a periodic timer to wakeup itself, and goes
408 to sleep waiting for the timer to fire. At the wakeup, the thread
409 then computes a wakeup latency value as the difference between
410 the current time and the absolute time that the timer was set
411 to expire.
412
413 The tracer prints two lines at every activation. The first is the
414 timer latency observed at the hardirq context before the
415 activation of the thread. The second is the timer latency observed
416 by the thread, which is the same level that cyclictest reports. The
417 ACTIVATION ID field serves to relate the irq execution to its
418 respective thread execution.
419
420 The tracer is build on top of osnoise tracer, and the osnoise:
421 events can be used to trace the source of interference from NMI,
422 IRQs and other threads. It also enables the capture of the
423 stacktrace at the IRQ context, which helps to identify the code
424 path that can cause thread delay.
425
426config MMIOTRACE
427 bool "Memory mapped IO tracing"
428 depends on HAVE_MMIOTRACE_SUPPORT && PCI
429 select GENERIC_TRACER
430 help
431 Mmiotrace traces Memory Mapped I/O access and is meant for
432 debugging and reverse engineering. It is called from the ioremap
433 implementation and works via page faults. Tracing is disabled by
434 default and can be enabled at run-time.
435
436 See Documentation/trace/mmiotrace.rst.
437 If you are not helping to develop drivers, say N.
438
439config ENABLE_DEFAULT_TRACERS
440 bool "Trace process context switches and events"
441 depends on !GENERIC_TRACER
442 select TRACING
443 help
444 This tracer hooks to various trace points in the kernel,
445 allowing the user to pick and choose which trace point they
446 want to trace. It also includes the sched_switch tracer plugin.
447
448config FTRACE_SYSCALLS
449 bool "Trace syscalls"
450 depends on HAVE_SYSCALL_TRACEPOINTS
451 select GENERIC_TRACER
452 select KALLSYMS
453 help
454 Basic tracer to catch the syscall entry and exit events.
455
456config TRACER_SNAPSHOT
457 bool "Create a snapshot trace buffer"
458 select TRACER_MAX_TRACE
459 help
460 Allow tracing users to take snapshot of the current buffer using the
461 ftrace interface, e.g.:
462
463 echo 1 > /sys/kernel/debug/tracing/snapshot
464 cat snapshot
465
466config TRACER_SNAPSHOT_PER_CPU_SWAP
467 bool "Allow snapshot to swap per CPU"
468 depends on TRACER_SNAPSHOT
469 select RING_BUFFER_ALLOW_SWAP
470 help
471 Allow doing a snapshot of a single CPU buffer instead of a
472 full swap (all buffers). If this is set, then the following is
473 allowed:
474
475 echo 1 > /sys/kernel/debug/tracing/per_cpu/cpu2/snapshot
476
477 After which, only the tracing buffer for CPU 2 was swapped with
478 the main tracing buffer, and the other CPU buffers remain the same.
479
480 When this is enabled, this adds a little more overhead to the
481 trace recording, as it needs to add some checks to synchronize
482 recording with swaps. But this does not affect the performance
483 of the overall system. This is enabled by default when the preempt
484 or irq latency tracers are enabled, as those need to swap as well
485 and already adds the overhead (plus a lot more).
486
487config TRACE_BRANCH_PROFILING
488 bool
489 select GENERIC_TRACER
490
491choice
492 prompt "Branch Profiling"
493 default BRANCH_PROFILE_NONE
494 help
495 The branch profiling is a software profiler. It will add hooks
496 into the C conditionals to test which path a branch takes.
497
498 The likely/unlikely profiler only looks at the conditions that
499 are annotated with a likely or unlikely macro.
500
501 The "all branch" profiler will profile every if-statement in the
502 kernel. This profiler will also enable the likely/unlikely
503 profiler.
504
505 Either of the above profilers adds a bit of overhead to the system.
506 If unsure, choose "No branch profiling".
507
508config BRANCH_PROFILE_NONE
509 bool "No branch profiling"
510 help
511 No branch profiling. Branch profiling adds a bit of overhead.
512 Only enable it if you want to analyse the branching behavior.
513 Otherwise keep it disabled.
514
515config PROFILE_ANNOTATED_BRANCHES
516 bool "Trace likely/unlikely profiler"
517 select TRACE_BRANCH_PROFILING
518 help
519 This tracer profiles all likely and unlikely macros
520 in the kernel. It will display the results in:
521
522 /sys/kernel/debug/tracing/trace_stat/branch_annotated
523
524 Note: this will add a significant overhead; only turn this
525 on if you need to profile the system's use of these macros.
526
527config PROFILE_ALL_BRANCHES
528 bool "Profile all if conditionals" if !FORTIFY_SOURCE
529 select TRACE_BRANCH_PROFILING
530 help
531 This tracer profiles all branch conditions. Every if ()
532 taken in the kernel is recorded whether it hit or miss.
533 The results will be displayed in:
534
535 /sys/kernel/debug/tracing/trace_stat/branch_all
536
537 This option also enables the likely/unlikely profiler.
538
539 This configuration, when enabled, will impose a great overhead
540 on the system. This should only be enabled when the system
541 is to be analyzed in much detail.
542endchoice
543
544config TRACING_BRANCHES
545 bool
546 help
547 Selected by tracers that will trace the likely and unlikely
548 conditions. This prevents the tracers themselves from being
549 profiled. Profiling the tracing infrastructure can only happen
550 when the likelys and unlikelys are not being traced.
551
552config BRANCH_TRACER
553 bool "Trace likely/unlikely instances"
554 depends on TRACE_BRANCH_PROFILING
555 select TRACING_BRANCHES
556 help
557 This traces the events of likely and unlikely condition
558 calls in the kernel. The difference between this and the
559 "Trace likely/unlikely profiler" is that this is not a
560 histogram of the callers, but actually places the calling
561 events into a running trace buffer to see when and where the
562 events happened, as well as their results.
563
564 Say N if unsure.
565
566config BLK_DEV_IO_TRACE
567 bool "Support for tracing block IO actions"
568 depends on SYSFS
569 depends on BLOCK
570 select RELAY
571 select DEBUG_FS
572 select TRACEPOINTS
573 select GENERIC_TRACER
574 select STACKTRACE
575 help
576 Say Y here if you want to be able to trace the block layer actions
577 on a given queue. Tracing allows you to see any traffic happening
578 on a block device queue. For more information (and the userspace
579 support tools needed), fetch the blktrace tools from:
580
581 git://git.kernel.dk/blktrace.git
582
583 Tracing also is possible using the ftrace interface, e.g.:
584
585 echo 1 > /sys/block/sda/sda1/trace/enable
586 echo blk > /sys/kernel/debug/tracing/current_tracer
587 cat /sys/kernel/debug/tracing/trace_pipe
588
589 If unsure, say N.
590
591config KPROBE_EVENTS
592 depends on KPROBES
593 depends on HAVE_REGS_AND_STACK_ACCESS_API
594 bool "Enable kprobes-based dynamic events"
595 select TRACING
596 select PROBE_EVENTS
597 select DYNAMIC_EVENTS
598 default y
599 help
600 This allows the user to add tracing events (similar to tracepoints)
601 on the fly via the ftrace interface. See
602 Documentation/trace/kprobetrace.rst for more details.
603
604 Those events can be inserted wherever kprobes can probe, and record
605 various register and memory values.
606
607 This option is also required by perf-probe subcommand of perf tools.
608 If you want to use perf tools, this option is strongly recommended.
609
610config KPROBE_EVENTS_ON_NOTRACE
611 bool "Do NOT protect notrace function from kprobe events"
612 depends on KPROBE_EVENTS
613 depends on DYNAMIC_FTRACE
614 default n
615 help
616 This is only for the developers who want to debug ftrace itself
617 using kprobe events.
618
619 If kprobes can use ftrace instead of breakpoint, ftrace related
620 functions are protected from kprobe-events to prevent an infinite
621 recursion or any unexpected execution path which leads to a kernel
622 crash.
623
624 This option disables such protection and allows you to put kprobe
625 events on ftrace functions for debugging ftrace by itself.
626 Note that this might let you shoot yourself in the foot.
627
628 If unsure, say N.
629
630config UPROBE_EVENTS
631 bool "Enable uprobes-based dynamic events"
632 depends on ARCH_SUPPORTS_UPROBES
633 depends on MMU
634 depends on PERF_EVENTS
635 select UPROBES
636 select PROBE_EVENTS
637 select DYNAMIC_EVENTS
638 select TRACING
639 default y
640 help
641 This allows the user to add tracing events on top of userspace
642 dynamic events (similar to tracepoints) on the fly via the trace
643 events interface. Those events can be inserted wherever uprobes
644 can probe, and record various registers.
645 This option is required if you plan to use perf-probe subcommand
646 of perf tools on user space applications.
647
648config BPF_EVENTS
649 depends on BPF_SYSCALL
650 depends on (KPROBE_EVENTS || UPROBE_EVENTS) && PERF_EVENTS
651 bool
652 default y
653 help
654 This allows the user to attach BPF programs to kprobe, uprobe, and
655 tracepoint events.
656
657config DYNAMIC_EVENTS
658 def_bool n
659
660config PROBE_EVENTS
661 def_bool n
662
663config BPF_KPROBE_OVERRIDE
664 bool "Enable BPF programs to override a kprobed function"
665 depends on BPF_EVENTS
666 depends on FUNCTION_ERROR_INJECTION
667 default n
668 help
669 Allows BPF to override the execution of a probed function and
670 set a different return value. This is used for error injection.
671
672config FTRACE_MCOUNT_RECORD
673 def_bool y
674 depends on DYNAMIC_FTRACE
675 depends on HAVE_FTRACE_MCOUNT_RECORD
676
677config FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
678 bool
679 depends on FTRACE_MCOUNT_RECORD
680
681config FTRACE_MCOUNT_USE_CC
682 def_bool y
683 depends on $(cc-option,-mrecord-mcount)
684 depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
685 depends on FTRACE_MCOUNT_RECORD
686
687config FTRACE_MCOUNT_USE_OBJTOOL
688 def_bool y
689 depends on HAVE_OBJTOOL_MCOUNT
690 depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
691 depends on !FTRACE_MCOUNT_USE_CC
692 depends on FTRACE_MCOUNT_RECORD
693
694config FTRACE_MCOUNT_USE_RECORDMCOUNT
695 def_bool y
696 depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
697 depends on !FTRACE_MCOUNT_USE_CC
698 depends on !FTRACE_MCOUNT_USE_OBJTOOL
699 depends on FTRACE_MCOUNT_RECORD
700
701config TRACING_MAP
702 bool
703 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
704 help
705 tracing_map is a special-purpose lock-free map for tracing,
706 separated out as a stand-alone facility in order to allow it
707 to be shared between multiple tracers. It isn't meant to be
708 generally used outside of that context, and is normally
709 selected by tracers that use it.
710
711config SYNTH_EVENTS
712 bool "Synthetic trace events"
713 select TRACING
714 select DYNAMIC_EVENTS
715 default n
716 help
717 Synthetic events are user-defined trace events that can be
718 used to combine data from other trace events or in fact any
719 data source. Synthetic events can be generated indirectly
720 via the trace() action of histogram triggers or directly
721 by way of an in-kernel API.
722
723 See Documentation/trace/events.rst or
724 Documentation/trace/histogram.rst for details and examples.
725
726 If in doubt, say N.
727
728config HIST_TRIGGERS
729 bool "Histogram triggers"
730 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
731 select TRACING_MAP
732 select TRACING
733 select DYNAMIC_EVENTS
734 select SYNTH_EVENTS
735 default n
736 help
737 Hist triggers allow one or more arbitrary trace event fields
738 to be aggregated into hash tables and dumped to stdout by
739 reading a debugfs/tracefs file. They're useful for
740 gathering quick and dirty (though precise) summaries of
741 event activity as an initial guide for further investigation
742 using more advanced tools.
743
744 Inter-event tracing of quantities such as latencies is also
745 supported using hist triggers under this option.
746
747 See Documentation/trace/histogram.rst.
748 If in doubt, say N.
749
750config TRACE_EVENT_INJECT
751 bool "Trace event injection"
752 depends on TRACING
753 help
754 Allow user-space to inject a specific trace event into the ring
755 buffer. This is mainly used for testing purpose.
756
757 If unsure, say N.
758
759config TRACEPOINT_BENCHMARK
760 bool "Add tracepoint that benchmarks tracepoints"
761 help
762 This option creates the tracepoint "benchmark:benchmark_event".
763 When the tracepoint is enabled, it kicks off a kernel thread that
764 goes into an infinite loop (calling cond_resched() to let other tasks
765 run), and calls the tracepoint. Each iteration will record the time
766 it took to write to the tracepoint and the next iteration that
767 data will be passed to the tracepoint itself. That is, the tracepoint
768 will report the time it took to do the previous tracepoint.
769 The string written to the tracepoint is a static string of 128 bytes
770 to keep the time the same. The initial string is simply a write of
771 "START". The second string records the cold cache time of the first
772 write which is not added to the rest of the calculations.
773
774 As it is a tight loop, it benchmarks as hot cache. That's fine because
775 we care most about hot paths that are probably in cache already.
776
777 An example of the output:
778
779 START
780 first=3672 [COLD CACHED]
781 last=632 first=3672 max=632 min=632 avg=316 std=446 std^2=199712
782 last=278 first=3672 max=632 min=278 avg=303 std=316 std^2=100337
783 last=277 first=3672 max=632 min=277 avg=296 std=258 std^2=67064
784 last=273 first=3672 max=632 min=273 avg=292 std=224 std^2=50411
785 last=273 first=3672 max=632 min=273 avg=288 std=200 std^2=40389
786 last=281 first=3672 max=632 min=273 avg=287 std=183 std^2=33666
787
788
789config RING_BUFFER_BENCHMARK
790 tristate "Ring buffer benchmark stress tester"
791 depends on RING_BUFFER
792 help
793 This option creates a test to stress the ring buffer and benchmark it.
794 It creates its own ring buffer such that it will not interfere with
795 any other users of the ring buffer (such as ftrace). It then creates
796 a producer and consumer that will run for 10 seconds and sleep for
797 10 seconds. Each interval it will print out the number of events
798 it recorded and give a rough estimate of how long each iteration took.
799
800 It does not disable interrupts or raise its priority, so it may be
801 affected by processes that are running.
802
803 If unsure, say N.
804
805config TRACE_EVAL_MAP_FILE
806 bool "Show eval mappings for trace events"
807 depends on TRACING
808 help
809 The "print fmt" of the trace events will show the enum/sizeof names
810 instead of their values. This can cause problems for user space tools
811 that use this string to parse the raw data as user space does not know
812 how to convert the string to its value.
813
814 To fix this, there's a special macro in the kernel that can be used
815 to convert an enum/sizeof into its value. If this macro is used, then
816 the print fmt strings will be converted to their values.
817
818 If something does not get converted properly, this option can be
819 used to show what enums/sizeof the kernel tried to convert.
820
821 This option is for debugging the conversions. A file is created
822 in the tracing directory called "eval_map" that will show the
823 names matched with their values and what trace event system they
824 belong too.
825
826 Normally, the mapping of the strings to values will be freed after
827 boot up or module load. With this option, they will not be freed, as
828 they are needed for the "eval_map" file. Enabling this option will
829 increase the memory footprint of the running kernel.
830
831 If unsure, say N.
832
833config FTRACE_RECORD_RECURSION
834 bool "Record functions that recurse in function tracing"
835 depends on FUNCTION_TRACER
836 help
837 All callbacks that attach to the function tracing have some sort
838 of protection against recursion. Even though the protection exists,
839 it adds overhead. This option will create a file in the tracefs
840 file system called "recursed_functions" that will list the functions
841 that triggered a recursion.
842
843 This will add more overhead to cases that have recursion.
844
845 If unsure, say N
846
847config FTRACE_RECORD_RECURSION_SIZE
848 int "Max number of recursed functions to record"
849 default 128
850 depends on FTRACE_RECORD_RECURSION
851 help
852 This defines the limit of number of functions that can be
853 listed in the "recursed_functions" file, that lists all
854 the functions that caused a recursion to happen.
855 This file can be reset, but the limit can not change in
856 size at runtime.
857
858config RING_BUFFER_RECORD_RECURSION
859 bool "Record functions that recurse in the ring buffer"
860 depends on FTRACE_RECORD_RECURSION
861 # default y, because it is coupled with FTRACE_RECORD_RECURSION
862 default y
863 help
864 The ring buffer has its own internal recursion. Although when
865 recursion happens it wont cause harm because of the protection,
866 but it does cause an unwanted overhead. Enabling this option will
867 place where recursion was detected into the ftrace "recursed_functions"
868 file.
869
870 This will add more overhead to cases that have recursion.
871
872config GCOV_PROFILE_FTRACE
873 bool "Enable GCOV profiling on ftrace subsystem"
874 depends on GCOV_KERNEL
875 help
876 Enable GCOV profiling on ftrace subsystem for checking
877 which functions/lines are tested.
878
879 If unsure, say N.
880
881 Note that on a kernel compiled with this config, ftrace will
882 run significantly slower.
883
884config FTRACE_SELFTEST
885 bool
886
887config FTRACE_STARTUP_TEST
888 bool "Perform a startup test on ftrace"
889 depends on GENERIC_TRACER
890 select FTRACE_SELFTEST
891 help
892 This option performs a series of startup tests on ftrace. On bootup
893 a series of tests are made to verify that the tracer is
894 functioning properly. It will do tests on all the configured
895 tracers of ftrace.
896
897config EVENT_TRACE_STARTUP_TEST
898 bool "Run selftest on trace events"
899 depends on FTRACE_STARTUP_TEST
900 default y
901 help
902 This option performs a test on all trace events in the system.
903 It basically just enables each event and runs some code that
904 will trigger events (not necessarily the event it enables)
905 This may take some time run as there are a lot of events.
906
907config EVENT_TRACE_TEST_SYSCALLS
908 bool "Run selftest on syscall events"
909 depends on EVENT_TRACE_STARTUP_TEST
910 help
911 This option will also enable testing every syscall event.
912 It only enables the event and disables it and runs various loads
913 with the event enabled. This adds a bit more time for kernel boot
914 up since it runs this on every system call defined.
915
916 TBD - enable a way to actually call the syscalls as we test their
917 events
918
919config RING_BUFFER_STARTUP_TEST
920 bool "Ring buffer startup self test"
921 depends on RING_BUFFER
922 help
923 Run a simple self test on the ring buffer on boot up. Late in the
924 kernel boot sequence, the test will start that kicks off
925 a thread per cpu. Each thread will write various size events
926 into the ring buffer. Another thread is created to send IPIs
927 to each of the threads, where the IPI handler will also write
928 to the ring buffer, to test/stress the nesting ability.
929 If any anomalies are discovered, a warning will be displayed
930 and all ring buffers will be disabled.
931
932 The test runs for 10 seconds. This will slow your boot time
933 by at least 10 more seconds.
934
935 At the end of the test, statics and more checks are done.
936 It will output the stats of each per cpu buffer. What
937 was written, the sizes, what was read, what was lost, and
938 other similar details.
939
940 If unsure, say N
941
942config RING_BUFFER_VALIDATE_TIME_DELTAS
943 bool "Verify ring buffer time stamp deltas"
944 depends on RING_BUFFER
945 help
946 This will audit the time stamps on the ring buffer sub
947 buffer to make sure that all the time deltas for the
948 events on a sub buffer matches the current time stamp.
949 This audit is performed for every event that is not
950 interrupted, or interrupting another event. A check
951 is also made when traversing sub buffers to make sure
952 that all the deltas on the previous sub buffer do not
953 add up to be greater than the current time stamp.
954
955 NOTE: This adds significant overhead to recording of events,
956 and should only be used to test the logic of the ring buffer.
957 Do not use it on production systems.
958
959 Only say Y if you understand what this does, and you
960 still want it enabled. Otherwise say N
961
962config MMIOTRACE_TEST
963 tristate "Test module for mmiotrace"
964 depends on MMIOTRACE && m
965 help
966 This is a dumb module for testing mmiotrace. It is very dangerous
967 as it will write garbage to IO memory starting at a given address.
968 However, it should be safe to use on e.g. unused portion of VRAM.
969
970 Say N, unless you absolutely know what you are doing.
971
972config PREEMPTIRQ_DELAY_TEST
973 tristate "Test module to create a preempt / IRQ disable delay thread to test latency tracers"
974 depends on m
975 help
976 Select this option to build a test module that can help test latency
977 tracers by executing a preempt or irq disable section with a user
978 configurable delay. The module busy waits for the duration of the
979 critical section.
980
981 For example, the following invocation generates a burst of three
982 irq-disabled critical sections for 500us:
983 modprobe preemptirq_delay_test test_mode=irq delay=500 burst_size=3
984
985 What's more, if you want to attach the test on the cpu which the latency
986 tracer is running on, specify cpu_affinity=cpu_num at the end of the
987 command.
988
989 If unsure, say N
990
991config SYNTH_EVENT_GEN_TEST
992 tristate "Test module for in-kernel synthetic event generation"
993 depends on SYNTH_EVENTS
994 help
995 This option creates a test module to check the base
996 functionality of in-kernel synthetic event definition and
997 generation.
998
999 To test, insert the module, and then check the trace buffer
1000 for the generated sample events.
1001
1002 If unsure, say N.
1003
1004config KPROBE_EVENT_GEN_TEST
1005 tristate "Test module for in-kernel kprobe event generation"
1006 depends on KPROBE_EVENTS
1007 help
1008 This option creates a test module to check the base
1009 functionality of in-kernel kprobe event definition.
1010
1011 To test, insert the module, and then check the trace buffer
1012 for the generated kprobe events.
1013
1014 If unsure, say N.
1015
1016config HIST_TRIGGERS_DEBUG
1017 bool "Hist trigger debug support"
1018 depends on HIST_TRIGGERS
1019 help
1020 Add "hist_debug" file for each event, which when read will
1021 dump out a bunch of internal details about the hist triggers
1022 defined on that event.
1023
1024 The hist_debug file serves a couple of purposes:
1025
1026 - Helps developers verify that nothing is broken.
1027
1028 - Provides educational information to support the details
1029 of the hist trigger internals as described by
1030 Documentation/trace/histogram-design.rst.
1031
1032 The hist_debug output only covers the data structures
1033 related to the histogram definitions themselves and doesn't
1034 display the internals of map buckets or variable values of
1035 running histograms.
1036
1037 If unsure, say N.
1038
1039endif # FTRACE
1040
1041endif # TRACING_SUPPORT
1042