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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 #
7 config USER_STACKTRACE_SUPPORT
8 bool
10 config NOP_TRACER
11 bool
13 config HAVE_FTRACE_NMI_ENTER
14 bool
15 help
16 See Documentation/trace/ftrace-design.rst
18 config HAVE_FUNCTION_TRACER
19 bool
20 help
21 See Documentation/trace/ftrace-design.rst
23 config HAVE_FUNCTION_GRAPH_TRACER
24 bool
25 help
26 See Documentation/trace/ftrace-design.rst
28 config HAVE_DYNAMIC_FTRACE
29 bool
30 help
31 See Documentation/trace/ftrace-design.rst
33 config HAVE_DYNAMIC_FTRACE_WITH_REGS
34 bool
36 config HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
37 bool
39 config HAVE_FTRACE_MCOUNT_RECORD
40 bool
41 help
42 See Documentation/trace/ftrace-design.rst
44 config HAVE_SYSCALL_TRACEPOINTS
45 bool
46 help
47 See Documentation/trace/ftrace-design.rst
49 config HAVE_FENTRY
50 bool
51 help
52 Arch supports the gcc options -pg with -mfentry
54 config HAVE_NOP_MCOUNT
55 bool
56 help
57 Arch supports the gcc options -pg with -mrecord-mcount and -nop-mcount
59 config HAVE_C_RECORDMCOUNT
60 bool
61 help
62 C version of recordmcount available?
64 config TRACER_MAX_TRACE
65 bool
67 config TRACE_CLOCK
68 bool
70 config RING_BUFFER
71 bool
72 select TRACE_CLOCK
73 select IRQ_WORK
75 config FTRACE_NMI_ENTER
76 bool
77 depends on HAVE_FTRACE_NMI_ENTER
78 default y
80 config EVENT_TRACING
81 select CONTEXT_SWITCH_TRACER
82 select GLOB
83 bool
85 config CONTEXT_SWITCH_TRACER
86 bool
88 config RING_BUFFER_ALLOW_SWAP
89 bool
90 help
91 Allow the use of ring_buffer_swap_cpu.
92 Adds a very slight overhead to tracing when enabled.
94 config PREEMPTIRQ_TRACEPOINTS
95 bool
96 depends on TRACE_PREEMPT_TOGGLE || TRACE_IRQFLAGS
97 select TRACING
98 default y
99 help
100 Create preempt/irq toggle tracepoints if needed, so that other parts
101 of the kernel can use them to generate or add hooks to them.
103 # All tracer options should select GENERIC_TRACER. For those options that are
104 # enabled by all tracers (context switch and event tracer) they select TRACING.
105 # This allows those options to appear when no other tracer is selected. But the
106 # options do not appear when something else selects it. We need the two options
107 # GENERIC_TRACER and TRACING to avoid circular dependencies to accomplish the
108 # hiding of the automatic options.
110 config TRACING
111 bool
112 select RING_BUFFER
113 select STACKTRACE if STACKTRACE_SUPPORT
114 select TRACEPOINTS
115 select NOP_TRACER
116 select BINARY_PRINTF
117 select EVENT_TRACING
118 select TRACE_CLOCK
120 config GENERIC_TRACER
121 bool
122 select TRACING
124 #
125 # Minimum requirements an architecture has to meet for us to
126 # be able to offer generic tracing facilities:
127 #
128 config TRACING_SUPPORT
129 bool
130 depends on TRACE_IRQFLAGS_SUPPORT
131 depends on STACKTRACE_SUPPORT
132 default y
134 if TRACING_SUPPORT
136 menuconfig FTRACE
137 bool "Tracers"
138 default y if DEBUG_KERNEL
139 help
140 Enable the kernel tracing infrastructure.
142 if FTRACE
144 config FUNCTION_TRACER
145 bool "Kernel Function Tracer"
146 depends on HAVE_FUNCTION_TRACER
147 select KALLSYMS
148 select GENERIC_TRACER
149 select CONTEXT_SWITCH_TRACER
150 select GLOB
151 select TASKS_RCU if PREEMPTION
152 help
153 Enable the kernel to trace every kernel function. This is done
154 by using a compiler feature to insert a small, 5-byte No-Operation
155 instruction at the beginning of every kernel function, which NOP
156 sequence is then dynamically patched into a tracer call when
157 tracing is enabled by the administrator. If it's runtime disabled
158 (the bootup default), then the overhead of the instructions is very
159 small and not measurable even in micro-benchmarks.
161 config FUNCTION_GRAPH_TRACER
162 bool "Kernel Function Graph Tracer"
163 depends on HAVE_FUNCTION_GRAPH_TRACER
164 depends on FUNCTION_TRACER
165 depends on !X86_32 || !CC_OPTIMIZE_FOR_SIZE
166 default y
167 help
168 Enable the kernel to trace a function at both its return
169 and its entry.
170 Its first purpose is to trace the duration of functions and
171 draw a call graph for each thread with some information like
172 the return value. This is done by setting the current return
173 address on the current task structure into a stack of calls.
175 config TRACE_PREEMPT_TOGGLE
176 bool
177 help
178 Enables hooks which will be called when preemption is first disabled,
179 and last enabled.
181 config PREEMPTIRQ_EVENTS
182 bool "Enable trace events for preempt and irq disable/enable"
183 select TRACE_IRQFLAGS
184 select TRACE_PREEMPT_TOGGLE if PREEMPTION
185 select GENERIC_TRACER
186 default n
187 help
188 Enable tracing of disable and enable events for preemption and irqs.
190 config IRQSOFF_TRACER
191 bool "Interrupts-off Latency Tracer"
192 default n
193 depends on TRACE_IRQFLAGS_SUPPORT
194 depends on !ARCH_USES_GETTIMEOFFSET
195 select TRACE_IRQFLAGS
196 select GENERIC_TRACER
197 select TRACER_MAX_TRACE
198 select RING_BUFFER_ALLOW_SWAP
199 select TRACER_SNAPSHOT
200 select TRACER_SNAPSHOT_PER_CPU_SWAP
201 help
202 This option measures the time spent in irqs-off critical
203 sections, with microsecond accuracy.
205 The default measurement method is a maximum search, which is
206 disabled by default and can be runtime (re-)started
207 via:
209 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
211 (Note that kernel size and overhead increase with this option
212 enabled. This option and the preempt-off timing option can be
213 used together or separately.)
215 config PREEMPT_TRACER
216 bool "Preemption-off Latency Tracer"
217 default n
218 depends on !ARCH_USES_GETTIMEOFFSET
219 depends on PREEMPTION
220 select GENERIC_TRACER
221 select TRACER_MAX_TRACE
222 select RING_BUFFER_ALLOW_SWAP
223 select TRACER_SNAPSHOT
224 select TRACER_SNAPSHOT_PER_CPU_SWAP
225 select TRACE_PREEMPT_TOGGLE
226 help
227 This option measures the time spent in preemption-off critical
228 sections, with microsecond accuracy.
230 The default measurement method is a maximum search, which is
231 disabled by default and can be runtime (re-)started
232 via:
234 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
236 (Note that kernel size and overhead increase with this option
237 enabled. This option and the irqs-off timing option can be
238 used together or separately.)
240 config SCHED_TRACER
241 bool "Scheduling Latency Tracer"
242 select GENERIC_TRACER
243 select CONTEXT_SWITCH_TRACER
244 select TRACER_MAX_TRACE
245 select TRACER_SNAPSHOT
246 help
247 This tracer tracks the latency of the highest priority task
248 to be scheduled in, starting from the point it has woken up.
250 config HWLAT_TRACER
251 bool "Tracer to detect hardware latencies (like SMIs)"
252 select GENERIC_TRACER
253 help
254 This tracer, when enabled will create one or more kernel threads,
255 depending on what the cpumask file is set to, which each thread
256 spinning in a loop looking for interruptions caused by
257 something other than the kernel. For example, if a
258 System Management Interrupt (SMI) takes a noticeable amount of
259 time, this tracer will detect it. This is useful for testing
260 if a system is reliable for Real Time tasks.
262 Some files are created in the tracing directory when this
263 is enabled:
265 hwlat_detector/width - time in usecs for how long to spin for
266 hwlat_detector/window - time in usecs between the start of each
267 iteration
269 A kernel thread is created that will spin with interrupts disabled
270 for "width" microseconds in every "window" cycle. It will not spin
271 for "window - width" microseconds, where the system can
272 continue to operate.
274 The output will appear in the trace and trace_pipe files.
276 When the tracer is not running, it has no affect on the system,
277 but when it is running, it can cause the system to be
278 periodically non responsive. Do not run this tracer on a
279 production system.
281 To enable this tracer, echo in "hwlat" into the current_tracer
282 file. Every time a latency is greater than tracing_thresh, it will
283 be recorded into the ring buffer.
285 config ENABLE_DEFAULT_TRACERS
286 bool "Trace process context switches and events"
287 depends on !GENERIC_TRACER
288 select TRACING
289 help
290 This tracer hooks to various trace points in the kernel,
291 allowing the user to pick and choose which trace point they
292 want to trace. It also includes the sched_switch tracer plugin.
294 config FTRACE_SYSCALLS
295 bool "Trace syscalls"
296 depends on HAVE_SYSCALL_TRACEPOINTS
297 select GENERIC_TRACER
298 select KALLSYMS
299 help
300 Basic tracer to catch the syscall entry and exit events.
302 config TRACER_SNAPSHOT
303 bool "Create a snapshot trace buffer"
304 select TRACER_MAX_TRACE
305 help
306 Allow tracing users to take snapshot of the current buffer using the
307 ftrace interface, e.g.:
309 echo 1 > /sys/kernel/debug/tracing/snapshot
310 cat snapshot
312 config TRACER_SNAPSHOT_PER_CPU_SWAP
313 bool "Allow snapshot to swap per CPU"
314 depends on TRACER_SNAPSHOT
315 select RING_BUFFER_ALLOW_SWAP
316 help
317 Allow doing a snapshot of a single CPU buffer instead of a
318 full swap (all buffers). If this is set, then the following is
319 allowed:
321 echo 1 > /sys/kernel/debug/tracing/per_cpu/cpu2/snapshot
323 After which, only the tracing buffer for CPU 2 was swapped with
324 the main tracing buffer, and the other CPU buffers remain the same.
326 When this is enabled, this adds a little more overhead to the
327 trace recording, as it needs to add some checks to synchronize
328 recording with swaps. But this does not affect the performance
329 of the overall system. This is enabled by default when the preempt
330 or irq latency tracers are enabled, as those need to swap as well
331 and already adds the overhead (plus a lot more).
333 config TRACE_BRANCH_PROFILING
334 bool
335 select GENERIC_TRACER
337 choice
338 prompt "Branch Profiling"
339 default BRANCH_PROFILE_NONE
340 help
341 The branch profiling is a software profiler. It will add hooks
342 into the C conditionals to test which path a branch takes.
344 The likely/unlikely profiler only looks at the conditions that
345 are annotated with a likely or unlikely macro.
347 The "all branch" profiler will profile every if-statement in the
348 kernel. This profiler will also enable the likely/unlikely
349 profiler.
351 Either of the above profilers adds a bit of overhead to the system.
352 If unsure, choose "No branch profiling".
354 config BRANCH_PROFILE_NONE
355 bool "No branch profiling"
356 help
357 No branch profiling. Branch profiling adds a bit of overhead.
358 Only enable it if you want to analyse the branching behavior.
359 Otherwise keep it disabled.
361 config PROFILE_ANNOTATED_BRANCHES
362 bool "Trace likely/unlikely profiler"
363 select TRACE_BRANCH_PROFILING
364 help
365 This tracer profiles all likely and unlikely macros
366 in the kernel. It will display the results in:
368 /sys/kernel/debug/tracing/trace_stat/branch_annotated
370 Note: this will add a significant overhead; only turn this
371 on if you need to profile the system's use of these macros.
373 config PROFILE_ALL_BRANCHES
374 bool "Profile all if conditionals" if !FORTIFY_SOURCE
375 select TRACE_BRANCH_PROFILING
376 imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED # avoid false positives
377 help
378 This tracer profiles all branch conditions. Every if ()
379 taken in the kernel is recorded whether it hit or miss.
380 The results will be displayed in:
382 /sys/kernel/debug/tracing/trace_stat/branch_all
384 This option also enables the likely/unlikely profiler.
386 This configuration, when enabled, will impose a great overhead
387 on the system. This should only be enabled when the system
388 is to be analyzed in much detail.
389 endchoice
391 config TRACING_BRANCHES
392 bool
393 help
394 Selected by tracers that will trace the likely and unlikely
395 conditions. This prevents the tracers themselves from being
396 profiled. Profiling the tracing infrastructure can only happen
397 when the likelys and unlikelys are not being traced.
399 config BRANCH_TRACER
400 bool "Trace likely/unlikely instances"
401 depends on TRACE_BRANCH_PROFILING
402 select TRACING_BRANCHES
403 help
404 This traces the events of likely and unlikely condition
405 calls in the kernel. The difference between this and the
406 "Trace likely/unlikely profiler" is that this is not a
407 histogram of the callers, but actually places the calling
408 events into a running trace buffer to see when and where the
409 events happened, as well as their results.
411 Say N if unsure.
413 config STACK_TRACER
414 bool "Trace max stack"
415 depends on HAVE_FUNCTION_TRACER
416 select FUNCTION_TRACER
417 select STACKTRACE
418 select KALLSYMS
419 help
420 This special tracer records the maximum stack footprint of the
421 kernel and displays it in /sys/kernel/debug/tracing/stack_trace.
423 This tracer works by hooking into every function call that the
424 kernel executes, and keeping a maximum stack depth value and
425 stack-trace saved. If this is configured with DYNAMIC_FTRACE
426 then it will not have any overhead while the stack tracer
427 is disabled.
429 To enable the stack tracer on bootup, pass in 'stacktrace'
430 on the kernel command line.
432 The stack tracer can also be enabled or disabled via the
433 sysctl kernel.stack_tracer_enabled
435 Say N if unsure.
437 config BLK_DEV_IO_TRACE
438 bool "Support for tracing block IO actions"
439 depends on SYSFS
440 depends on BLOCK
441 select RELAY
442 select DEBUG_FS
443 select TRACEPOINTS
444 select GENERIC_TRACER
445 select STACKTRACE
446 help
447 Say Y here if you want to be able to trace the block layer actions
448 on a given queue. Tracing allows you to see any traffic happening
449 on a block device queue. For more information (and the userspace
450 support tools needed), fetch the blktrace tools from:
452 git://git.kernel.dk/blktrace.git
454 Tracing also is possible using the ftrace interface, e.g.:
456 echo 1 > /sys/block/sda/sda1/trace/enable
457 echo blk > /sys/kernel/debug/tracing/current_tracer
458 cat /sys/kernel/debug/tracing/trace_pipe
460 If unsure, say N.
462 config KPROBE_EVENTS
463 depends on KPROBES
464 depends on HAVE_REGS_AND_STACK_ACCESS_API
465 bool "Enable kprobes-based dynamic events"
466 select TRACING
467 select PROBE_EVENTS
468 select DYNAMIC_EVENTS
469 default y
470 help
471 This allows the user to add tracing events (similar to tracepoints)
472 on the fly via the ftrace interface. See
473 Documentation/trace/kprobetrace.rst for more details.
475 Those events can be inserted wherever kprobes can probe, and record
476 various register and memory values.
478 This option is also required by perf-probe subcommand of perf tools.
479 If you want to use perf tools, this option is strongly recommended.
481 config KPROBE_EVENTS_ON_NOTRACE
482 bool "Do NOT protect notrace function from kprobe events"
483 depends on KPROBE_EVENTS
484 depends on KPROBES_ON_FTRACE
485 default n
486 help
487 This is only for the developers who want to debug ftrace itself
488 using kprobe events.
490 If kprobes can use ftrace instead of breakpoint, ftrace related
491 functions are protected from kprobe-events to prevent an infinit
492 recursion or any unexpected execution path which leads to a kernel
493 crash.
495 This option disables such protection and allows you to put kprobe
496 events on ftrace functions for debugging ftrace by itself.
497 Note that this might let you shoot yourself in the foot.
499 If unsure, say N.
501 config UPROBE_EVENTS
502 bool "Enable uprobes-based dynamic events"
503 depends on ARCH_SUPPORTS_UPROBES
504 depends on MMU
505 depends on PERF_EVENTS
506 select UPROBES
507 select PROBE_EVENTS
508 select DYNAMIC_EVENTS
509 select TRACING
510 default y
511 help
512 This allows the user to add tracing events on top of userspace
513 dynamic events (similar to tracepoints) on the fly via the trace
514 events interface. Those events can be inserted wherever uprobes
515 can probe, and record various registers.
516 This option is required if you plan to use perf-probe subcommand
517 of perf tools on user space applications.
519 config BPF_EVENTS
520 depends on BPF_SYSCALL
521 depends on (KPROBE_EVENTS || UPROBE_EVENTS) && PERF_EVENTS
522 bool
523 default y
524 help
525 This allows the user to attach BPF programs to kprobe, uprobe, and
526 tracepoint events.
528 config DYNAMIC_EVENTS
529 def_bool n
531 config PROBE_EVENTS
532 def_bool n
534 config DYNAMIC_FTRACE
535 bool "enable/disable function tracing dynamically"
536 depends on FUNCTION_TRACER
537 depends on HAVE_DYNAMIC_FTRACE
538 default y
539 help
540 This option will modify all the calls to function tracing
541 dynamically (will patch them out of the binary image and
542 replace them with a No-Op instruction) on boot up. During
543 compile time, a table is made of all the locations that ftrace
544 can function trace, and this table is linked into the kernel
545 image. When this is enabled, functions can be individually
546 enabled, and the functions not enabled will not affect
547 performance of the system.
549 See the files in /sys/kernel/debug/tracing:
550 available_filter_functions
551 set_ftrace_filter
552 set_ftrace_notrace
554 This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but
555 otherwise has native performance as long as no tracing is active.
557 config DYNAMIC_FTRACE_WITH_REGS
558 def_bool y
559 depends on DYNAMIC_FTRACE
560 depends on HAVE_DYNAMIC_FTRACE_WITH_REGS
562 config DYNAMIC_FTRACE_WITH_DIRECT_CALLS
563 def_bool y
564 depends on DYNAMIC_FTRACE
565 depends on HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
567 config FUNCTION_PROFILER
568 bool "Kernel function profiler"
569 depends on FUNCTION_TRACER
570 default n
571 help
572 This option enables the kernel function profiler. A file is created
573 in debugfs called function_profile_enabled which defaults to zero.
574 When a 1 is echoed into this file profiling begins, and when a
575 zero is entered, profiling stops. A "functions" file is created in
576 the trace_stat directory; this file shows the list of functions that
577 have been hit and their counters.
579 If in doubt, say N.
581 config BPF_KPROBE_OVERRIDE
582 bool "Enable BPF programs to override a kprobed function"
583 depends on BPF_EVENTS
584 depends on FUNCTION_ERROR_INJECTION
585 default n
586 help
587 Allows BPF to override the execution of a probed function and
588 set a different return value. This is used for error injection.
590 config FTRACE_MCOUNT_RECORD
591 def_bool y
592 depends on DYNAMIC_FTRACE
593 depends on HAVE_FTRACE_MCOUNT_RECORD
595 config FTRACE_SELFTEST
596 bool
598 config FTRACE_STARTUP_TEST
599 bool "Perform a startup test on ftrace"
600 depends on GENERIC_TRACER
601 select FTRACE_SELFTEST
602 help
603 This option performs a series of startup tests on ftrace. On bootup
604 a series of tests are made to verify that the tracer is
605 functioning properly. It will do tests on all the configured
606 tracers of ftrace.
608 config EVENT_TRACE_STARTUP_TEST
609 bool "Run selftest on trace events"
610 depends on FTRACE_STARTUP_TEST
611 default y
612 help
613 This option performs a test on all trace events in the system.
614 It basically just enables each event and runs some code that
615 will trigger events (not necessarily the event it enables)
616 This may take some time run as there are a lot of events.
618 config EVENT_TRACE_TEST_SYSCALLS
619 bool "Run selftest on syscall events"
620 depends on EVENT_TRACE_STARTUP_TEST
621 help
622 This option will also enable testing every syscall event.
623 It only enables the event and disables it and runs various loads
624 with the event enabled. This adds a bit more time for kernel boot
625 up since it runs this on every system call defined.
627 TBD - enable a way to actually call the syscalls as we test their
628 events
630 config MMIOTRACE
631 bool "Memory mapped IO tracing"
632 depends on HAVE_MMIOTRACE_SUPPORT && PCI
633 select GENERIC_TRACER
634 help
635 Mmiotrace traces Memory Mapped I/O access and is meant for
636 debugging and reverse engineering. It is called from the ioremap
637 implementation and works via page faults. Tracing is disabled by
638 default and can be enabled at run-time.
640 See Documentation/trace/mmiotrace.rst.
641 If you are not helping to develop drivers, say N.
643 config TRACING_MAP
644 bool
645 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
646 help
647 tracing_map is a special-purpose lock-free map for tracing,
648 separated out as a stand-alone facility in order to allow it
649 to be shared between multiple tracers. It isn't meant to be
650 generally used outside of that context, and is normally
651 selected by tracers that use it.
653 config HIST_TRIGGERS
654 bool "Histogram triggers"
655 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
656 select TRACING_MAP
657 select TRACING
658 select DYNAMIC_EVENTS
659 default n
660 help
661 Hist triggers allow one or more arbitrary trace event fields
662 to be aggregated into hash tables and dumped to stdout by
663 reading a debugfs/tracefs file. They're useful for
664 gathering quick and dirty (though precise) summaries of
665 event activity as an initial guide for further investigation
666 using more advanced tools.
668 Inter-event tracing of quantities such as latencies is also
669 supported using hist triggers under this option.
671 See Documentation/trace/histogram.rst.
672 If in doubt, say N.
674 config TRACE_EVENT_INJECT
675 bool "Trace event injection"
676 depends on TRACING
677 help
678 Allow user-space to inject a specific trace event into the ring
679 buffer. This is mainly used for testing purpose.
681 If unsure, say N.
683 config MMIOTRACE_TEST
684 tristate "Test module for mmiotrace"
685 depends on MMIOTRACE && m
686 help
687 This is a dumb module for testing mmiotrace. It is very dangerous
688 as it will write garbage to IO memory starting at a given address.
689 However, it should be safe to use on e.g. unused portion of VRAM.
691 Say N, unless you absolutely know what you are doing.
693 config TRACEPOINT_BENCHMARK
694 bool "Add tracepoint that benchmarks tracepoints"
695 help
696 This option creates the tracepoint "benchmark:benchmark_event".
697 When the tracepoint is enabled, it kicks off a kernel thread that
698 goes into an infinite loop (calling cond_sched() to let other tasks
699 run), and calls the tracepoint. Each iteration will record the time
700 it took to write to the tracepoint and the next iteration that
701 data will be passed to the tracepoint itself. That is, the tracepoint
702 will report the time it took to do the previous tracepoint.
703 The string written to the tracepoint is a static string of 128 bytes
704 to keep the time the same. The initial string is simply a write of
705 "START". The second string records the cold cache time of the first
706 write which is not added to the rest of the calculations.
708 As it is a tight loop, it benchmarks as hot cache. That's fine because
709 we care most about hot paths that are probably in cache already.
711 An example of the output:
713 START
714 first=3672 [COLD CACHED]
715 last=632 first=3672 max=632 min=632 avg=316 std=446 std^2=199712
716 last=278 first=3672 max=632 min=278 avg=303 std=316 std^2=100337
717 last=277 first=3672 max=632 min=277 avg=296 std=258 std^2=67064
718 last=273 first=3672 max=632 min=273 avg=292 std=224 std^2=50411
719 last=273 first=3672 max=632 min=273 avg=288 std=200 std^2=40389
720 last=281 first=3672 max=632 min=273 avg=287 std=183 std^2=33666
723 config RING_BUFFER_BENCHMARK
724 tristate "Ring buffer benchmark stress tester"
725 depends on RING_BUFFER
726 help
727 This option creates a test to stress the ring buffer and benchmark it.
728 It creates its own ring buffer such that it will not interfere with
729 any other users of the ring buffer (such as ftrace). It then creates
730 a producer and consumer that will run for 10 seconds and sleep for
731 10 seconds. Each interval it will print out the number of events
732 it recorded and give a rough estimate of how long each iteration took.
734 It does not disable interrupts or raise its priority, so it may be
735 affected by processes that are running.
737 If unsure, say N.
739 config RING_BUFFER_STARTUP_TEST
740 bool "Ring buffer startup self test"
741 depends on RING_BUFFER
742 help
743 Run a simple self test on the ring buffer on boot up. Late in the
744 kernel boot sequence, the test will start that kicks off
745 a thread per cpu. Each thread will write various size events
746 into the ring buffer. Another thread is created to send IPIs
747 to each of the threads, where the IPI handler will also write
748 to the ring buffer, to test/stress the nesting ability.
749 If any anomalies are discovered, a warning will be displayed
750 and all ring buffers will be disabled.
752 The test runs for 10 seconds. This will slow your boot time
753 by at least 10 more seconds.
755 At the end of the test, statics and more checks are done.
756 It will output the stats of each per cpu buffer. What
757 was written, the sizes, what was read, what was lost, and
758 other similar details.
760 If unsure, say N
762 config PREEMPTIRQ_DELAY_TEST
763 tristate "Preempt / IRQ disable delay thread to test latency tracers"
764 depends on m
765 help
766 Select this option to build a test module that can help test latency
767 tracers by executing a preempt or irq disable section with a user
768 configurable delay. The module busy waits for the duration of the
769 critical section.
771 For example, the following invocation generates a burst of three
772 irq-disabled critical sections for 500us:
773 modprobe preemptirq_delay_test test_mode=irq delay=500 burst_size=3
775 If unsure, say N
777 config TRACE_EVAL_MAP_FILE
778 bool "Show eval mappings for trace events"
779 depends on TRACING
780 help
781 The "print fmt" of the trace events will show the enum/sizeof names
782 instead of their values. This can cause problems for user space tools
783 that use this string to parse the raw data as user space does not know
784 how to convert the string to its value.
786 To fix this, there's a special macro in the kernel that can be used
787 to convert an enum/sizeof into its value. If this macro is used, then
788 the print fmt strings will be converted to their values.
790 If something does not get converted properly, this option can be
791 used to show what enums/sizeof the kernel tried to convert.
793 This option is for debugging the conversions. A file is created
794 in the tracing directory called "eval_map" that will show the
795 names matched with their values and what trace event system they
796 belong too.
798 Normally, the mapping of the strings to values will be freed after
799 boot up or module load. With this option, they will not be freed, as
800 they are needed for the "eval_map" file. Enabling this option will
801 increase the memory footprint of the running kernel.
803 If unsure, say N.
805 config 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.
812 If unsure, say N.
814 Note that on a kernel compiled with this config, ftrace will
815 run significantly slower.
817 endif # FTRACE
819 endif # TRACING_SUPPORT