1 # SPDX-License-Identifier: GPL-2.0-only
3 # Architectures that offer an FUNCTION_TRACER implementation should
4 # select HAVE_FUNCTION_TRACER:
7 config USER_STACKTRACE_SUPPORT
13 config HAVE_FUNCTION_TRACER
16 See Documentation/trace/ftrace-design.rst
18 config HAVE_FUNCTION_GRAPH_TRACER
21 See Documentation/trace/ftrace-design.rst
23 config HAVE_DYNAMIC_FTRACE
26 See Documentation/trace/ftrace-design.rst
28 config HAVE_DYNAMIC_FTRACE_WITH_REGS
31 config HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
34 config HAVE_DYNAMIC_FTRACE_WITH_ARGS
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().
43 config HAVE_FTRACE_MCOUNT_RECORD
46 See Documentation/trace/ftrace-design.rst
48 config HAVE_SYSCALL_TRACEPOINTS
51 See Documentation/trace/ftrace-design.rst
56 Arch supports the gcc options -pg with -mfentry
58 config HAVE_NOP_MCOUNT
61 Arch supports the gcc options -pg with -mrecord-mcount and -nop-mcount
63 config HAVE_OBJTOOL_MCOUNT
66 Arch supports objtool --mcount
68 config HAVE_C_RECORDMCOUNT
71 C version of recordmcount available?
73 config TRACER_MAX_TRACE
85 select CONTEXT_SWITCH_TRACER
89 config CONTEXT_SWITCH_TRACER
92 config RING_BUFFER_ALLOW_SWAP
95 Allow the use of ring_buffer_swap_cpu.
96 Adds a very slight overhead to tracing when enabled.
98 config PREEMPTIRQ_TRACEPOINTS
100 depends on TRACE_PREEMPT_TOGGLE || TRACE_IRQFLAGS
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.
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.
117 select STACKTRACE if STACKTRACE_SUPPORT
124 config GENERIC_TRACER
129 # Minimum requirements an architecture has to meet for us to
130 # be able to offer generic tracing facilities:
132 config TRACING_SUPPORT
134 depends on TRACE_IRQFLAGS_SUPPORT
135 depends on STACKTRACE_SUPPORT
142 default y if DEBUG_KERNEL
144 Enable the kernel tracing infrastructure.
148 config BOOTTIME_TRACING
149 bool "Boot-time Tracing support"
153 Enable developer to setup ftrace subsystem via supplemental
154 kernel cmdline at boot time for debugging (tracing) driver
155 initialization and boot process.
157 config FUNCTION_TRACER
158 bool "Kernel Function Tracer"
159 depends on HAVE_FUNCTION_TRACER
161 select GENERIC_TRACER
162 select CONTEXT_SWITCH_TRACER
164 select TASKS_RCU if PREEMPTION
165 select TASKS_RUDE_RCU
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.
175 config 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
182 Enable the kernel to trace a function at both its return
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.
189 config DYNAMIC_FTRACE
190 bool "enable/disable function tracing dynamically"
191 depends on FUNCTION_TRACER
192 depends on HAVE_DYNAMIC_FTRACE
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.
204 See the files in /sys/kernel/debug/tracing:
205 available_filter_functions
209 This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but
210 otherwise has native performance as long as no tracing is active.
212 config DYNAMIC_FTRACE_WITH_REGS
214 depends on DYNAMIC_FTRACE
215 depends on HAVE_DYNAMIC_FTRACE_WITH_REGS
217 config DYNAMIC_FTRACE_WITH_DIRECT_CALLS
219 depends on DYNAMIC_FTRACE_WITH_REGS
220 depends on HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
222 config DYNAMIC_FTRACE_WITH_ARGS
224 depends on DYNAMIC_FTRACE
225 depends on HAVE_DYNAMIC_FTRACE_WITH_ARGS
227 config FUNCTION_PROFILER
228 bool "Kernel function profiler"
229 depends on FUNCTION_TRACER
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.
242 bool "Trace max stack"
243 depends on HAVE_FUNCTION_TRACER
244 select FUNCTION_TRACER
248 This special tracer records the maximum stack footprint of the
249 kernel and displays it in /sys/kernel/debug/tracing/stack_trace.
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
257 To enable the stack tracer on bootup, pass in 'stacktrace'
258 on the kernel command line.
260 The stack tracer can also be enabled or disabled via the
261 sysctl kernel.stack_tracer_enabled
265 config TRACE_PREEMPT_TOGGLE
268 Enables hooks which will be called when preemption is first disabled,
271 config IRQSOFF_TRACER
272 bool "Interrupts-off Latency Tracer"
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
282 This option measures the time spent in irqs-off critical
283 sections, with microsecond accuracy.
285 The default measurement method is a maximum search, which is
286 disabled by default and can be runtime (re-)started
289 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
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.)
295 config PREEMPT_TRACER
296 bool "Preemption-off Latency Tracer"
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
306 This option measures the time spent in preemption-off critical
307 sections, with microsecond accuracy.
309 The default measurement method is a maximum search, which is
310 disabled by default and can be runtime (re-)started
313 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
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.)
320 bool "Scheduling Latency Tracer"
321 select GENERIC_TRACER
322 select CONTEXT_SWITCH_TRACER
323 select TRACER_MAX_TRACE
324 select TRACER_SNAPSHOT
326 This tracer tracks the latency of the highest priority task
327 to be scheduled in, starting from the point it has woken up.
330 bool "Tracer to detect hardware latencies (like SMIs)"
331 select GENERIC_TRACER
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.
341 Some files are created in the tracing directory when this
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
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
353 The output will appear in the trace and trace_pipe files.
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
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.
364 config OSNOISE_TRACER
365 bool "OS Noise tracer"
366 select GENERIC_TRACER
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.
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.
390 In addition to the tracer, a set of tracepoints were added to
391 facilitate the identification of the osnoise source.
393 The output will appear in the trace and trace_pipe files.
395 To enable this tracer, echo in "osnoise" into the current_tracer
398 config TIMERLAT_TRACER
399 bool "Timerlat tracer"
400 select OSNOISE_TRACER
401 select GENERIC_TRACER
403 The timerlat tracer aims to help the preemptive kernel developers
404 to find sources of wakeup latencies of real-time threads.
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
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.
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.
427 bool "Memory mapped IO tracing"
428 depends on HAVE_MMIOTRACE_SUPPORT && PCI
429 select GENERIC_TRACER
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.
436 See Documentation/trace/mmiotrace.rst.
437 If you are not helping to develop drivers, say N.
439 config ENABLE_DEFAULT_TRACERS
440 bool "Trace process context switches and events"
441 depends on !GENERIC_TRACER
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.
448 config FTRACE_SYSCALLS
449 bool "Trace syscalls"
450 depends on HAVE_SYSCALL_TRACEPOINTS
451 select GENERIC_TRACER
454 Basic tracer to catch the syscall entry and exit events.
456 config TRACER_SNAPSHOT
457 bool "Create a snapshot trace buffer"
458 select TRACER_MAX_TRACE
460 Allow tracing users to take snapshot of the current buffer using the
461 ftrace interface, e.g.:
463 echo 1 > /sys/kernel/debug/tracing/snapshot
466 config TRACER_SNAPSHOT_PER_CPU_SWAP
467 bool "Allow snapshot to swap per CPU"
468 depends on TRACER_SNAPSHOT
469 select RING_BUFFER_ALLOW_SWAP
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
475 echo 1 > /sys/kernel/debug/tracing/per_cpu/cpu2/snapshot
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.
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).
487 config TRACE_BRANCH_PROFILING
489 select GENERIC_TRACER
492 prompt "Branch Profiling"
493 default BRANCH_PROFILE_NONE
495 The branch profiling is a software profiler. It will add hooks
496 into the C conditionals to test which path a branch takes.
498 The likely/unlikely profiler only looks at the conditions that
499 are annotated with a likely or unlikely macro.
501 The "all branch" profiler will profile every if-statement in the
502 kernel. This profiler will also enable the likely/unlikely
505 Either of the above profilers adds a bit of overhead to the system.
506 If unsure, choose "No branch profiling".
508 config BRANCH_PROFILE_NONE
509 bool "No branch profiling"
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.
515 config PROFILE_ANNOTATED_BRANCHES
516 bool "Trace likely/unlikely profiler"
517 select TRACE_BRANCH_PROFILING
519 This tracer profiles all likely and unlikely macros
520 in the kernel. It will display the results in:
522 /sys/kernel/debug/tracing/trace_stat/branch_annotated
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.
527 config PROFILE_ALL_BRANCHES
528 bool "Profile all if conditionals" if !FORTIFY_SOURCE
529 select TRACE_BRANCH_PROFILING
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:
535 /sys/kernel/debug/tracing/trace_stat/branch_all
537 This option also enables the likely/unlikely profiler.
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.
544 config TRACING_BRANCHES
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.
553 bool "Trace likely/unlikely instances"
554 depends on TRACE_BRANCH_PROFILING
555 select TRACING_BRANCHES
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.
566 config BLK_DEV_IO_TRACE
567 bool "Support for tracing block IO actions"
573 select GENERIC_TRACER
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:
581 git://git.kernel.dk/blktrace.git
583 Tracing also is possible using the ftrace interface, e.g.:
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
593 depends on HAVE_REGS_AND_STACK_ACCESS_API
594 bool "Enable kprobes-based dynamic events"
597 select DYNAMIC_EVENTS
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.
604 Those events can be inserted wherever kprobes can probe, and record
605 various register and memory values.
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.
610 config KPROBE_EVENTS_ON_NOTRACE
611 bool "Do NOT protect notrace function from kprobe events"
612 depends on KPROBE_EVENTS
613 depends on DYNAMIC_FTRACE
616 This is only for the developers who want to debug ftrace itself
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
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.
631 bool "Enable uprobes-based dynamic events"
632 depends on ARCH_SUPPORTS_UPROBES
634 depends on PERF_EVENTS
637 select DYNAMIC_EVENTS
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.
649 depends on BPF_SYSCALL
650 depends on (KPROBE_EVENTS || UPROBE_EVENTS) && PERF_EVENTS
654 This allows the user to attach BPF programs to kprobe, uprobe, and
657 config DYNAMIC_EVENTS
663 config BPF_KPROBE_OVERRIDE
664 bool "Enable BPF programs to override a kprobed function"
665 depends on BPF_EVENTS
666 depends on FUNCTION_ERROR_INJECTION
669 Allows BPF to override the execution of a probed function and
670 set a different return value. This is used for error injection.
672 config FTRACE_MCOUNT_RECORD
674 depends on DYNAMIC_FTRACE
675 depends on HAVE_FTRACE_MCOUNT_RECORD
677 config FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
679 depends on FTRACE_MCOUNT_RECORD
681 config FTRACE_MCOUNT_USE_CC
683 depends on $(cc-option,-mrecord-mcount)
684 depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
685 depends on FTRACE_MCOUNT_RECORD
687 config FTRACE_MCOUNT_USE_OBJTOOL
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
694 config FTRACE_MCOUNT_USE_RECORDMCOUNT
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
703 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
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.
712 bool "Synthetic trace events"
714 select DYNAMIC_EVENTS
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.
723 See Documentation/trace/events.rst or
724 Documentation/trace/histogram.rst for details and examples.
729 bool "Histogram triggers"
730 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
733 select DYNAMIC_EVENTS
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.
744 Inter-event tracing of quantities such as latencies is also
745 supported using hist triggers under this option.
747 See Documentation/trace/histogram.rst.
750 config TRACE_EVENT_INJECT
751 bool "Trace event injection"
754 Allow user-space to inject a specific trace event into the ring
755 buffer. This is mainly used for testing purpose.
759 config TRACEPOINT_BENCHMARK
760 bool "Add tracepoint that benchmarks tracepoints"
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.
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.
777 An example of the output:
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
789 config RING_BUFFER_BENCHMARK
790 tristate "Ring buffer benchmark stress tester"
791 depends on RING_BUFFER
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.
800 It does not disable interrupts or raise its priority, so it may be
801 affected by processes that are running.
805 config TRACE_EVAL_MAP_FILE
806 bool "Show eval mappings for trace events"
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.
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.
818 If something does not get converted properly, this option can be
819 used to show what enums/sizeof the kernel tried to convert.
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
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.
833 config FTRACE_RECORD_RECURSION
834 bool "Record functions that recurse in function tracing"
835 depends on FUNCTION_TRACER
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.
843 This will add more overhead to cases that have recursion.
847 config FTRACE_RECORD_RECURSION_SIZE
848 int "Max number of recursed functions to record"
850 depends on FTRACE_RECORD_RECURSION
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
858 config 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
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"
870 This will add more overhead to cases that have recursion.
872 config GCOV_PROFILE_FTRACE
873 bool "Enable GCOV profiling on ftrace subsystem"
874 depends on GCOV_KERNEL
876 Enable GCOV profiling on ftrace subsystem for checking
877 which functions/lines are tested.
881 Note that on a kernel compiled with this config, ftrace will
882 run significantly slower.
884 config FTRACE_SELFTEST
887 config FTRACE_STARTUP_TEST
888 bool "Perform a startup test on ftrace"
889 depends on GENERIC_TRACER
890 select FTRACE_SELFTEST
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
897 config EVENT_TRACE_STARTUP_TEST
898 bool "Run selftest on trace events"
899 depends on FTRACE_STARTUP_TEST
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.
907 config EVENT_TRACE_TEST_SYSCALLS
908 bool "Run selftest on syscall events"
909 depends on EVENT_TRACE_STARTUP_TEST
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.
916 TBD - enable a way to actually call the syscalls as we test their
919 config RING_BUFFER_STARTUP_TEST
920 bool "Ring buffer startup self test"
921 depends on RING_BUFFER
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.
932 The test runs for 10 seconds. This will slow your boot time
933 by at least 10 more seconds.
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.
942 config RING_BUFFER_VALIDATE_TIME_DELTAS
943 bool "Verify ring buffer time stamp deltas"
944 depends on RING_BUFFER
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.
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.
959 Only say Y if you understand what this does, and you
960 still want it enabled. Otherwise say N
962 config MMIOTRACE_TEST
963 tristate "Test module for mmiotrace"
964 depends on MMIOTRACE && m
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.
970 Say N, unless you absolutely know what you are doing.
972 config PREEMPTIRQ_DELAY_TEST
973 tristate "Test module to create a preempt / IRQ disable delay thread to test latency tracers"
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
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
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
991 config SYNTH_EVENT_GEN_TEST
992 tristate "Test module for in-kernel synthetic event generation"
993 depends on SYNTH_EVENTS
995 This option creates a test module to check the base
996 functionality of in-kernel synthetic event definition and
999 To test, insert the module, and then check the trace buffer
1000 for the generated sample events.
1004 config KPROBE_EVENT_GEN_TEST
1005 tristate "Test module for in-kernel kprobe event generation"
1006 depends on KPROBE_EVENTS
1008 This option creates a test module to check the base
1009 functionality of in-kernel kprobe event definition.
1011 To test, insert the module, and then check the trace buffer
1012 for the generated kprobe events.
1016 config HIST_TRIGGERS_DEBUG
1017 bool "Hist trigger debug support"
1018 depends on HIST_TRIGGERS
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.
1024 The hist_debug file serves a couple of purposes:
1026 - Helps developers verify that nothing is broken.
1028 - Provides educational information to support the details
1029 of the hist trigger internals as described by
1030 Documentation/trace/histogram-design.rst.
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
1041 endif # TRACING_SUPPORT
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