projects/linux·blob v5.12 · refs

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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 FUNCTION_PROFILER
223 bool "Kernel function profiler"
224 depends on FUNCTION_TRACER
225 default n
226 help
227 This option enables the kernel function profiler. A file is created
228 in debugfs called function_profile_enabled which defaults to zero.
229 When a 1 is echoed into this file profiling begins, and when a
230 zero is entered, profiling stops. A "functions" file is created in
231 the trace_stat directory; this file shows the list of functions that
232 have been hit and their counters.
233
234 If in doubt, say N.
235
236config STACK_TRACER
237 bool "Trace max stack"
238 depends on HAVE_FUNCTION_TRACER
239 select FUNCTION_TRACER
240 select STACKTRACE
241 select KALLSYMS
242 help
243 This special tracer records the maximum stack footprint of the
244 kernel and displays it in /sys/kernel/debug/tracing/stack_trace.
245
246 This tracer works by hooking into every function call that the
247 kernel executes, and keeping a maximum stack depth value and
248 stack-trace saved. If this is configured with DYNAMIC_FTRACE
249 then it will not have any overhead while the stack tracer
250 is disabled.
251
252 To enable the stack tracer on bootup, pass in 'stacktrace'
253 on the kernel command line.
254
255 The stack tracer can also be enabled or disabled via the
256 sysctl kernel.stack_tracer_enabled
257
258 Say N if unsure.
259
260config TRACE_PREEMPT_TOGGLE
261 bool
262 help
263 Enables hooks which will be called when preemption is first disabled,
264 and last enabled.
265
266config IRQSOFF_TRACER
267 bool "Interrupts-off Latency Tracer"
268 default n
269 depends on TRACE_IRQFLAGS_SUPPORT
270 select TRACE_IRQFLAGS
271 select GENERIC_TRACER
272 select TRACER_MAX_TRACE
273 select RING_BUFFER_ALLOW_SWAP
274 select TRACER_SNAPSHOT
275 select TRACER_SNAPSHOT_PER_CPU_SWAP
276 help
277 This option measures the time spent in irqs-off critical
278 sections, with microsecond accuracy.
279
280 The default measurement method is a maximum search, which is
281 disabled by default and can be runtime (re-)started
282 via:
283
284 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
285
286 (Note that kernel size and overhead increase with this option
287 enabled. This option and the preempt-off timing option can be
288 used together or separately.)
289
290config PREEMPT_TRACER
291 bool "Preemption-off Latency Tracer"
292 default n
293 depends on PREEMPTION
294 select GENERIC_TRACER
295 select TRACER_MAX_TRACE
296 select RING_BUFFER_ALLOW_SWAP
297 select TRACER_SNAPSHOT
298 select TRACER_SNAPSHOT_PER_CPU_SWAP
299 select TRACE_PREEMPT_TOGGLE
300 help
301 This option measures the time spent in preemption-off critical
302 sections, with microsecond accuracy.
303
304 The default measurement method is a maximum search, which is
305 disabled by default and can be runtime (re-)started
306 via:
307
308 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
309
310 (Note that kernel size and overhead increase with this option
311 enabled. This option and the irqs-off timing option can be
312 used together or separately.)
313
314config SCHED_TRACER
315 bool "Scheduling Latency Tracer"
316 select GENERIC_TRACER
317 select CONTEXT_SWITCH_TRACER
318 select TRACER_MAX_TRACE
319 select TRACER_SNAPSHOT
320 help
321 This tracer tracks the latency of the highest priority task
322 to be scheduled in, starting from the point it has woken up.
323
324config HWLAT_TRACER
325 bool "Tracer to detect hardware latencies (like SMIs)"
326 select GENERIC_TRACER
327 help
328 This tracer, when enabled will create one or more kernel threads,
329 depending on what the cpumask file is set to, which each thread
330 spinning in a loop looking for interruptions caused by
331 something other than the kernel. For example, if a
332 System Management Interrupt (SMI) takes a noticeable amount of
333 time, this tracer will detect it. This is useful for testing
334 if a system is reliable for Real Time tasks.
335
336 Some files are created in the tracing directory when this
337 is enabled:
338
339 hwlat_detector/width - time in usecs for how long to spin for
340 hwlat_detector/window - time in usecs between the start of each
341 iteration
342
343 A kernel thread is created that will spin with interrupts disabled
344 for "width" microseconds in every "window" cycle. It will not spin
345 for "window - width" microseconds, where the system can
346 continue to operate.
347
348 The output will appear in the trace and trace_pipe files.
349
350 When the tracer is not running, it has no affect on the system,
351 but when it is running, it can cause the system to be
352 periodically non responsive. Do not run this tracer on a
353 production system.
354
355 To enable this tracer, echo in "hwlat" into the current_tracer
356 file. Every time a latency is greater than tracing_thresh, it will
357 be recorded into the ring buffer.
358
359config MMIOTRACE
360 bool "Memory mapped IO tracing"
361 depends on HAVE_MMIOTRACE_SUPPORT && PCI
362 select GENERIC_TRACER
363 help
364 Mmiotrace traces Memory Mapped I/O access and is meant for
365 debugging and reverse engineering. It is called from the ioremap
366 implementation and works via page faults. Tracing is disabled by
367 default and can be enabled at run-time.
368
369 See Documentation/trace/mmiotrace.rst.
370 If you are not helping to develop drivers, say N.
371
372config ENABLE_DEFAULT_TRACERS
373 bool "Trace process context switches and events"
374 depends on !GENERIC_TRACER
375 select TRACING
376 help
377 This tracer hooks to various trace points in the kernel,
378 allowing the user to pick and choose which trace point they
379 want to trace. It also includes the sched_switch tracer plugin.
380
381config FTRACE_SYSCALLS
382 bool "Trace syscalls"
383 depends on HAVE_SYSCALL_TRACEPOINTS
384 select GENERIC_TRACER
385 select KALLSYMS
386 help
387 Basic tracer to catch the syscall entry and exit events.
388
389config TRACER_SNAPSHOT
390 bool "Create a snapshot trace buffer"
391 select TRACER_MAX_TRACE
392 help
393 Allow tracing users to take snapshot of the current buffer using the
394 ftrace interface, e.g.:
395
396 echo 1 > /sys/kernel/debug/tracing/snapshot
397 cat snapshot
398
399config TRACER_SNAPSHOT_PER_CPU_SWAP
400 bool "Allow snapshot to swap per CPU"
401 depends on TRACER_SNAPSHOT
402 select RING_BUFFER_ALLOW_SWAP
403 help
404 Allow doing a snapshot of a single CPU buffer instead of a
405 full swap (all buffers). If this is set, then the following is
406 allowed:
407
408 echo 1 > /sys/kernel/debug/tracing/per_cpu/cpu2/snapshot
409
410 After which, only the tracing buffer for CPU 2 was swapped with
411 the main tracing buffer, and the other CPU buffers remain the same.
412
413 When this is enabled, this adds a little more overhead to the
414 trace recording, as it needs to add some checks to synchronize
415 recording with swaps. But this does not affect the performance
416 of the overall system. This is enabled by default when the preempt
417 or irq latency tracers are enabled, as those need to swap as well
418 and already adds the overhead (plus a lot more).
419
420config TRACE_BRANCH_PROFILING
421 bool
422 select GENERIC_TRACER
423
424choice
425 prompt "Branch Profiling"
426 default BRANCH_PROFILE_NONE
427 help
428 The branch profiling is a software profiler. It will add hooks
429 into the C conditionals to test which path a branch takes.
430
431 The likely/unlikely profiler only looks at the conditions that
432 are annotated with a likely or unlikely macro.
433
434 The "all branch" profiler will profile every if-statement in the
435 kernel. This profiler will also enable the likely/unlikely
436 profiler.
437
438 Either of the above profilers adds a bit of overhead to the system.
439 If unsure, choose "No branch profiling".
440
441config BRANCH_PROFILE_NONE
442 bool "No branch profiling"
443 help
444 No branch profiling. Branch profiling adds a bit of overhead.
445 Only enable it if you want to analyse the branching behavior.
446 Otherwise keep it disabled.
447
448config PROFILE_ANNOTATED_BRANCHES
449 bool "Trace likely/unlikely profiler"
450 select TRACE_BRANCH_PROFILING
451 help
452 This tracer profiles all likely and unlikely macros
453 in the kernel. It will display the results in:
454
455 /sys/kernel/debug/tracing/trace_stat/branch_annotated
456
457 Note: this will add a significant overhead; only turn this
458 on if you need to profile the system's use of these macros.
459
460config PROFILE_ALL_BRANCHES
461 bool "Profile all if conditionals" if !FORTIFY_SOURCE
462 select TRACE_BRANCH_PROFILING
463 help
464 This tracer profiles all branch conditions. Every if ()
465 taken in the kernel is recorded whether it hit or miss.
466 The results will be displayed in:
467
468 /sys/kernel/debug/tracing/trace_stat/branch_all
469
470 This option also enables the likely/unlikely profiler.
471
472 This configuration, when enabled, will impose a great overhead
473 on the system. This should only be enabled when the system
474 is to be analyzed in much detail.
475endchoice
476
477config TRACING_BRANCHES
478 bool
479 help
480 Selected by tracers that will trace the likely and unlikely
481 conditions. This prevents the tracers themselves from being
482 profiled. Profiling the tracing infrastructure can only happen
483 when the likelys and unlikelys are not being traced.
484
485config BRANCH_TRACER
486 bool "Trace likely/unlikely instances"
487 depends on TRACE_BRANCH_PROFILING
488 select TRACING_BRANCHES
489 help
490 This traces the events of likely and unlikely condition
491 calls in the kernel. The difference between this and the
492 "Trace likely/unlikely profiler" is that this is not a
493 histogram of the callers, but actually places the calling
494 events into a running trace buffer to see when and where the
495 events happened, as well as their results.
496
497 Say N if unsure.
498
499config BLK_DEV_IO_TRACE
500 bool "Support for tracing block IO actions"
501 depends on SYSFS
502 depends on BLOCK
503 select RELAY
504 select DEBUG_FS
505 select TRACEPOINTS
506 select GENERIC_TRACER
507 select STACKTRACE
508 help
509 Say Y here if you want to be able to trace the block layer actions
510 on a given queue. Tracing allows you to see any traffic happening
511 on a block device queue. For more information (and the userspace
512 support tools needed), fetch the blktrace tools from:
513
514 git://git.kernel.dk/blktrace.git
515
516 Tracing also is possible using the ftrace interface, e.g.:
517
518 echo 1 > /sys/block/sda/sda1/trace/enable
519 echo blk > /sys/kernel/debug/tracing/current_tracer
520 cat /sys/kernel/debug/tracing/trace_pipe
521
522 If unsure, say N.
523
524config KPROBE_EVENTS
525 depends on KPROBES
526 depends on HAVE_REGS_AND_STACK_ACCESS_API
527 bool "Enable kprobes-based dynamic events"
528 select TRACING
529 select PROBE_EVENTS
530 select DYNAMIC_EVENTS
531 default y
532 help
533 This allows the user to add tracing events (similar to tracepoints)
534 on the fly via the ftrace interface. See
535 Documentation/trace/kprobetrace.rst for more details.
536
537 Those events can be inserted wherever kprobes can probe, and record
538 various register and memory values.
539
540 This option is also required by perf-probe subcommand of perf tools.
541 If you want to use perf tools, this option is strongly recommended.
542
543config KPROBE_EVENTS_ON_NOTRACE
544 bool "Do NOT protect notrace function from kprobe events"
545 depends on KPROBE_EVENTS
546 depends on DYNAMIC_FTRACE
547 default n
548 help
549 This is only for the developers who want to debug ftrace itself
550 using kprobe events.
551
552 If kprobes can use ftrace instead of breakpoint, ftrace related
553 functions are protected from kprobe-events to prevent an infinite
554 recursion or any unexpected execution path which leads to a kernel
555 crash.
556
557 This option disables such protection and allows you to put kprobe
558 events on ftrace functions for debugging ftrace by itself.
559 Note that this might let you shoot yourself in the foot.
560
561 If unsure, say N.
562
563config UPROBE_EVENTS
564 bool "Enable uprobes-based dynamic events"
565 depends on ARCH_SUPPORTS_UPROBES
566 depends on MMU
567 depends on PERF_EVENTS
568 select UPROBES
569 select PROBE_EVENTS
570 select DYNAMIC_EVENTS
571 select TRACING
572 default y
573 help
574 This allows the user to add tracing events on top of userspace
575 dynamic events (similar to tracepoints) on the fly via the trace
576 events interface. Those events can be inserted wherever uprobes
577 can probe, and record various registers.
578 This option is required if you plan to use perf-probe subcommand
579 of perf tools on user space applications.
580
581config BPF_EVENTS
582 depends on BPF_SYSCALL
583 depends on (KPROBE_EVENTS || UPROBE_EVENTS) && PERF_EVENTS
584 bool
585 default y
586 help
587 This allows the user to attach BPF programs to kprobe, uprobe, and
588 tracepoint events.
589
590config DYNAMIC_EVENTS
591 def_bool n
592
593config PROBE_EVENTS
594 def_bool n
595
596config BPF_KPROBE_OVERRIDE
597 bool "Enable BPF programs to override a kprobed function"
598 depends on BPF_EVENTS
599 depends on FUNCTION_ERROR_INJECTION
600 default n
601 help
602 Allows BPF to override the execution of a probed function and
603 set a different return value. This is used for error injection.
604
605config FTRACE_MCOUNT_RECORD
606 def_bool y
607 depends on DYNAMIC_FTRACE
608 depends on HAVE_FTRACE_MCOUNT_RECORD
609
610config FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
611 bool
612 depends on FTRACE_MCOUNT_RECORD
613
614config FTRACE_MCOUNT_USE_CC
615 def_bool y
616 depends on $(cc-option,-mrecord-mcount)
617 depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
618 depends on FTRACE_MCOUNT_RECORD
619
620config FTRACE_MCOUNT_USE_OBJTOOL
621 def_bool y
622 depends on HAVE_OBJTOOL_MCOUNT
623 depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
624 depends on !FTRACE_MCOUNT_USE_CC
625 depends on FTRACE_MCOUNT_RECORD
626
627config FTRACE_MCOUNT_USE_RECORDMCOUNT
628 def_bool y
629 depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
630 depends on !FTRACE_MCOUNT_USE_CC
631 depends on !FTRACE_MCOUNT_USE_OBJTOOL
632 depends on FTRACE_MCOUNT_RECORD
633
634config TRACING_MAP
635 bool
636 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
637 help
638 tracing_map is a special-purpose lock-free map for tracing,
639 separated out as a stand-alone facility in order to allow it
640 to be shared between multiple tracers. It isn't meant to be
641 generally used outside of that context, and is normally
642 selected by tracers that use it.
643
644config SYNTH_EVENTS
645 bool "Synthetic trace events"
646 select TRACING
647 select DYNAMIC_EVENTS
648 default n
649 help
650 Synthetic events are user-defined trace events that can be
651 used to combine data from other trace events or in fact any
652 data source. Synthetic events can be generated indirectly
653 via the trace() action of histogram triggers or directly
654 by way of an in-kernel API.
655
656 See Documentation/trace/events.rst or
657 Documentation/trace/histogram.rst for details and examples.
658
659 If in doubt, say N.
660
661config HIST_TRIGGERS
662 bool "Histogram triggers"
663 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
664 select TRACING_MAP
665 select TRACING
666 select DYNAMIC_EVENTS
667 select SYNTH_EVENTS
668 default n
669 help
670 Hist triggers allow one or more arbitrary trace event fields
671 to be aggregated into hash tables and dumped to stdout by
672 reading a debugfs/tracefs file. They're useful for
673 gathering quick and dirty (though precise) summaries of
674 event activity as an initial guide for further investigation
675 using more advanced tools.
676
677 Inter-event tracing of quantities such as latencies is also
678 supported using hist triggers under this option.
679
680 See Documentation/trace/histogram.rst.
681 If in doubt, say N.
682
683config TRACE_EVENT_INJECT
684 bool "Trace event injection"
685 depends on TRACING
686 help
687 Allow user-space to inject a specific trace event into the ring
688 buffer. This is mainly used for testing purpose.
689
690 If unsure, say N.
691
692config TRACEPOINT_BENCHMARK
693 bool "Add tracepoint that benchmarks tracepoints"
694 help
695 This option creates the tracepoint "benchmark:benchmark_event".
696 When the tracepoint is enabled, it kicks off a kernel thread that
697 goes into an infinite loop (calling cond_resched() to let other tasks
698 run), and calls the tracepoint. Each iteration will record the time
699 it took to write to the tracepoint and the next iteration that
700 data will be passed to the tracepoint itself. That is, the tracepoint
701 will report the time it took to do the previous tracepoint.
702 The string written to the tracepoint is a static string of 128 bytes
703 to keep the time the same. The initial string is simply a write of
704 "START". The second string records the cold cache time of the first
705 write which is not added to the rest of the calculations.
706
707 As it is a tight loop, it benchmarks as hot cache. That's fine because
708 we care most about hot paths that are probably in cache already.
709
710 An example of the output:
711
712 START
713 first=3672 [COLD CACHED]
714 last=632 first=3672 max=632 min=632 avg=316 std=446 std^2=199712
715 last=278 first=3672 max=632 min=278 avg=303 std=316 std^2=100337
716 last=277 first=3672 max=632 min=277 avg=296 std=258 std^2=67064
717 last=273 first=3672 max=632 min=273 avg=292 std=224 std^2=50411
718 last=273 first=3672 max=632 min=273 avg=288 std=200 std^2=40389
719 last=281 first=3672 max=632 min=273 avg=287 std=183 std^2=33666
720
721
722config RING_BUFFER_BENCHMARK
723 tristate "Ring buffer benchmark stress tester"
724 depends on RING_BUFFER
725 help
726 This option creates a test to stress the ring buffer and benchmark it.
727 It creates its own ring buffer such that it will not interfere with
728 any other users of the ring buffer (such as ftrace). It then creates
729 a producer and consumer that will run for 10 seconds and sleep for
730 10 seconds. Each interval it will print out the number of events
731 it recorded and give a rough estimate of how long each iteration took.
732
733 It does not disable interrupts or raise its priority, so it may be
734 affected by processes that are running.
735
736 If unsure, say N.
737
738config TRACE_EVAL_MAP_FILE
739 bool "Show eval mappings for trace events"
740 depends on TRACING
741 help
742 The "print fmt" of the trace events will show the enum/sizeof names
743 instead of their values. This can cause problems for user space tools
744 that use this string to parse the raw data as user space does not know
745 how to convert the string to its value.
746
747 To fix this, there's a special macro in the kernel that can be used
748 to convert an enum/sizeof into its value. If this macro is used, then
749 the print fmt strings will be converted to their values.
750
751 If something does not get converted properly, this option can be
752 used to show what enums/sizeof the kernel tried to convert.
753
754 This option is for debugging the conversions. A file is created
755 in the tracing directory called "eval_map" that will show the
756 names matched with their values and what trace event system they
757 belong too.
758
759 Normally, the mapping of the strings to values will be freed after
760 boot up or module load. With this option, they will not be freed, as
761 they are needed for the "eval_map" file. Enabling this option will
762 increase the memory footprint of the running kernel.
763
764 If unsure, say N.
765
766config FTRACE_RECORD_RECURSION
767 bool "Record functions that recurse in function tracing"
768 depends on FUNCTION_TRACER
769 help
770 All callbacks that attach to the function tracing have some sort
771 of protection against recursion. Even though the protection exists,
772 it adds overhead. This option will create a file in the tracefs
773 file system called "recursed_functions" that will list the functions
774 that triggered a recursion.
775
776 This will add more overhead to cases that have recursion.
777
778 If unsure, say N
779
780config FTRACE_RECORD_RECURSION_SIZE
781 int "Max number of recursed functions to record"
782 default 128
783 depends on FTRACE_RECORD_RECURSION
784 help
785 This defines the limit of number of functions that can be
786 listed in the "recursed_functions" file, that lists all
787 the functions that caused a recursion to happen.
788 This file can be reset, but the limit can not change in
789 size at runtime.
790
791config RING_BUFFER_RECORD_RECURSION
792 bool "Record functions that recurse in the ring buffer"
793 depends on FTRACE_RECORD_RECURSION
794 # default y, because it is coupled with FTRACE_RECORD_RECURSION
795 default y
796 help
797 The ring buffer has its own internal recursion. Although when
798 recursion happens it wont cause harm because of the protection,
799 but it does cause an unwanted overhead. Enabling this option will
800 place where recursion was detected into the ftrace "recursed_functions"
801 file.
802
803 This will add more overhead to cases that have recursion.
804
805config GCOV_PROFILE_FTRACE
806 bool "Enable GCOV profiling on ftrace subsystem"
807 depends on GCOV_KERNEL
808 help
809 Enable GCOV profiling on ftrace subsystem for checking
810 which functions/lines are tested.
811
812 If unsure, say N.
813
814 Note that on a kernel compiled with this config, ftrace will
815 run significantly slower.
816
817config FTRACE_SELFTEST
818 bool
819
820config FTRACE_STARTUP_TEST
821 bool "Perform a startup test on ftrace"
822 depends on GENERIC_TRACER
823 select FTRACE_SELFTEST
824 help
825 This option performs a series of startup tests on ftrace. On bootup
826 a series of tests are made to verify that the tracer is
827 functioning properly. It will do tests on all the configured
828 tracers of ftrace.
829
830config EVENT_TRACE_STARTUP_TEST
831 bool "Run selftest on trace events"
832 depends on FTRACE_STARTUP_TEST
833 default y
834 help
835 This option performs a test on all trace events in the system.
836 It basically just enables each event and runs some code that
837 will trigger events (not necessarily the event it enables)
838 This may take some time run as there are a lot of events.
839
840config EVENT_TRACE_TEST_SYSCALLS
841 bool "Run selftest on syscall events"
842 depends on EVENT_TRACE_STARTUP_TEST
843 help
844 This option will also enable testing every syscall event.
845 It only enables the event and disables it and runs various loads
846 with the event enabled. This adds a bit more time for kernel boot
847 up since it runs this on every system call defined.
848
849 TBD - enable a way to actually call the syscalls as we test their
850 events
851
852config RING_BUFFER_STARTUP_TEST
853 bool "Ring buffer startup self test"
854 depends on RING_BUFFER
855 help
856 Run a simple self test on the ring buffer on boot up. Late in the
857 kernel boot sequence, the test will start that kicks off
858 a thread per cpu. Each thread will write various size events
859 into the ring buffer. Another thread is created to send IPIs
860 to each of the threads, where the IPI handler will also write
861 to the ring buffer, to test/stress the nesting ability.
862 If any anomalies are discovered, a warning will be displayed
863 and all ring buffers will be disabled.
864
865 The test runs for 10 seconds. This will slow your boot time
866 by at least 10 more seconds.
867
868 At the end of the test, statics and more checks are done.
869 It will output the stats of each per cpu buffer. What
870 was written, the sizes, what was read, what was lost, and
871 other similar details.
872
873 If unsure, say N
874
875config RING_BUFFER_VALIDATE_TIME_DELTAS
876 bool "Verify ring buffer time stamp deltas"
877 depends on RING_BUFFER
878 help
879 This will audit the time stamps on the ring buffer sub
880 buffer to make sure that all the time deltas for the
881 events on a sub buffer matches the current time stamp.
882 This audit is performed for every event that is not
883 interrupted, or interrupting another event. A check
884 is also made when traversing sub buffers to make sure
885 that all the deltas on the previous sub buffer do not
886 add up to be greater than the current time stamp.
887
888 NOTE: This adds significant overhead to recording of events,
889 and should only be used to test the logic of the ring buffer.
890 Do not use it on production systems.
891
892 Only say Y if you understand what this does, and you
893 still want it enabled. Otherwise say N
894
895config MMIOTRACE_TEST
896 tristate "Test module for mmiotrace"
897 depends on MMIOTRACE && m
898 help
899 This is a dumb module for testing mmiotrace. It is very dangerous
900 as it will write garbage to IO memory starting at a given address.
901 However, it should be safe to use on e.g. unused portion of VRAM.
902
903 Say N, unless you absolutely know what you are doing.
904
905config PREEMPTIRQ_DELAY_TEST
906 tristate "Test module to create a preempt / IRQ disable delay thread to test latency tracers"
907 depends on m
908 help
909 Select this option to build a test module that can help test latency
910 tracers by executing a preempt or irq disable section with a user
911 configurable delay. The module busy waits for the duration of the
912 critical section.
913
914 For example, the following invocation generates a burst of three
915 irq-disabled critical sections for 500us:
916 modprobe preemptirq_delay_test test_mode=irq delay=500 burst_size=3
917
918 What's more, if you want to attach the test on the cpu which the latency
919 tracer is running on, specify cpu_affinity=cpu_num at the end of the
920 command.
921
922 If unsure, say N
923
924config SYNTH_EVENT_GEN_TEST
925 tristate "Test module for in-kernel synthetic event generation"
926 depends on SYNTH_EVENTS
927 help
928 This option creates a test module to check the base
929 functionality of in-kernel synthetic event definition and
930 generation.
931
932 To test, insert the module, and then check the trace buffer
933 for the generated sample events.
934
935 If unsure, say N.
936
937config KPROBE_EVENT_GEN_TEST
938 tristate "Test module for in-kernel kprobe event generation"
939 depends on KPROBE_EVENTS
940 help
941 This option creates a test module to check the base
942 functionality of in-kernel kprobe event definition.
943
944 To test, insert the module, and then check the trace buffer
945 for the generated kprobe events.
946
947 If unsure, say N.
948
949config HIST_TRIGGERS_DEBUG
950 bool "Hist trigger debug support"
951 depends on HIST_TRIGGERS
952 help
953 Add "hist_debug" file for each event, which when read will
954 dump out a bunch of internal details about the hist triggers
955 defined on that event.
956
957 The hist_debug file serves a couple of purposes:
958
959 - Helps developers verify that nothing is broken.
960
961 - Provides educational information to support the details
962 of the hist trigger internals as described by
963 Documentation/trace/histogram-design.rst.
964
965 The hist_debug output only covers the data structures
966 related to the histogram definitions themselves and doesn't
967 display the internals of map buckets or variable values of
968 running histograms.
969
970 If unsure, say N.
971
972endif # FTRACE
973
974endif # TRACING_SUPPORT
975