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 FUNCTION_PROFILER
223 bool "Kernel function profiler"
224 depends on FUNCTION_TRACER
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.
237 bool "Trace max stack"
238 depends on HAVE_FUNCTION_TRACER
239 select FUNCTION_TRACER
243 This special tracer records the maximum stack footprint of the
244 kernel and displays it in /sys/kernel/debug/tracing/stack_trace.
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
252 To enable the stack tracer on bootup, pass in 'stacktrace'
253 on the kernel command line.
255 The stack tracer can also be enabled or disabled via the
256 sysctl kernel.stack_tracer_enabled
260 config TRACE_PREEMPT_TOGGLE
263 Enables hooks which will be called when preemption is first disabled,
266 config IRQSOFF_TRACER
267 bool "Interrupts-off Latency Tracer"
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
277 This option measures the time spent in irqs-off critical
278 sections, with microsecond accuracy.
280 The default measurement method is a maximum search, which is
281 disabled by default and can be runtime (re-)started
284 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
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.)
290 config PREEMPT_TRACER
291 bool "Preemption-off Latency Tracer"
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
301 This option measures the time spent in preemption-off critical
302 sections, with microsecond accuracy.
304 The default measurement method is a maximum search, which is
305 disabled by default and can be runtime (re-)started
308 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
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.)
315 bool "Scheduling Latency Tracer"
316 select GENERIC_TRACER
317 select CONTEXT_SWITCH_TRACER
318 select TRACER_MAX_TRACE
319 select TRACER_SNAPSHOT
321 This tracer tracks the latency of the highest priority task
322 to be scheduled in, starting from the point it has woken up.
325 bool "Tracer to detect hardware latencies (like SMIs)"
326 select GENERIC_TRACER
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.
336 Some files are created in the tracing directory when this
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
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
348 The output will appear in the trace and trace_pipe files.
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
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.
359 config OSNOISE_TRACER
360 bool "OS Noise tracer"
361 select GENERIC_TRACER
363 In the context of high-performance computing (HPC), the Operating
364 System Noise (osnoise) refers to the interference experienced by an
365 application due to activities inside the operating system. In the
366 context of Linux, NMIs, IRQs, SoftIRQs, and any other system thread
367 can cause noise to the system. Moreover, hardware-related jobs can
368 also cause noise, for example, via SMIs.
370 The osnoise tracer leverages the hwlat_detector by running a similar
371 loop with preemption, SoftIRQs and IRQs enabled, thus allowing all
372 the sources of osnoise during its execution. The osnoise tracer takes
373 note of the entry and exit point of any source of interferences,
374 increasing a per-cpu interference counter. It saves an interference
375 counter for each source of interference. The interference counter for
376 NMI, IRQs, SoftIRQs, and threads is increased anytime the tool
377 observes these interferences' entry events. When a noise happens
378 without any interference from the operating system level, the
379 hardware noise counter increases, pointing to a hardware-related
380 noise. In this way, osnoise can account for any source of
381 interference. At the end of the period, the osnoise tracer prints
382 the sum of all noise, the max single noise, the percentage of CPU
383 available for the thread, and the counters for the noise sources.
385 In addition to the tracer, a set of tracepoints were added to
386 facilitate the identification of the osnoise source.
388 The output will appear in the trace and trace_pipe files.
390 To enable this tracer, echo in "osnoise" into the current_tracer
393 config TIMERLAT_TRACER
394 bool "Timerlat tracer"
395 select OSNOISE_TRACER
396 select GENERIC_TRACER
398 The timerlat tracer aims to help the preemptive kernel developers
399 to find sources of wakeup latencies of real-time threads.
401 The tracer creates a per-cpu kernel thread with real-time priority.
402 The tracer thread sets a periodic timer to wakeup itself, and goes
403 to sleep waiting for the timer to fire. At the wakeup, the thread
404 then computes a wakeup latency value as the difference between
405 the current time and the absolute time that the timer was set
408 The tracer prints two lines at every activation. The first is the
409 timer latency observed at the hardirq context before the
410 activation of the thread. The second is the timer latency observed
411 by the thread, which is the same level that cyclictest reports. The
412 ACTIVATION ID field serves to relate the irq execution to its
413 respective thread execution.
415 The tracer is build on top of osnoise tracer, and the osnoise:
416 events can be used to trace the source of interference from NMI,
417 IRQs and other threads. It also enables the capture of the
418 stacktrace at the IRQ context, which helps to identify the code
419 path that can cause thread delay.
422 bool "Memory mapped IO tracing"
423 depends on HAVE_MMIOTRACE_SUPPORT && PCI
424 select GENERIC_TRACER
426 Mmiotrace traces Memory Mapped I/O access and is meant for
427 debugging and reverse engineering. It is called from the ioremap
428 implementation and works via page faults. Tracing is disabled by
429 default and can be enabled at run-time.
431 See Documentation/trace/mmiotrace.rst.
432 If you are not helping to develop drivers, say N.
434 config ENABLE_DEFAULT_TRACERS
435 bool "Trace process context switches and events"
436 depends on !GENERIC_TRACER
439 This tracer hooks to various trace points in the kernel,
440 allowing the user to pick and choose which trace point they
441 want to trace. It also includes the sched_switch tracer plugin.
443 config FTRACE_SYSCALLS
444 bool "Trace syscalls"
445 depends on HAVE_SYSCALL_TRACEPOINTS
446 select GENERIC_TRACER
449 Basic tracer to catch the syscall entry and exit events.
451 config TRACER_SNAPSHOT
452 bool "Create a snapshot trace buffer"
453 select TRACER_MAX_TRACE
455 Allow tracing users to take snapshot of the current buffer using the
456 ftrace interface, e.g.:
458 echo 1 > /sys/kernel/debug/tracing/snapshot
461 config TRACER_SNAPSHOT_PER_CPU_SWAP
462 bool "Allow snapshot to swap per CPU"
463 depends on TRACER_SNAPSHOT
464 select RING_BUFFER_ALLOW_SWAP
466 Allow doing a snapshot of a single CPU buffer instead of a
467 full swap (all buffers). If this is set, then the following is
470 echo 1 > /sys/kernel/debug/tracing/per_cpu/cpu2/snapshot
472 After which, only the tracing buffer for CPU 2 was swapped with
473 the main tracing buffer, and the other CPU buffers remain the same.
475 When this is enabled, this adds a little more overhead to the
476 trace recording, as it needs to add some checks to synchronize
477 recording with swaps. But this does not affect the performance
478 of the overall system. This is enabled by default when the preempt
479 or irq latency tracers are enabled, as those need to swap as well
480 and already adds the overhead (plus a lot more).
482 config TRACE_BRANCH_PROFILING
484 select GENERIC_TRACER
487 prompt "Branch Profiling"
488 default BRANCH_PROFILE_NONE
490 The branch profiling is a software profiler. It will add hooks
491 into the C conditionals to test which path a branch takes.
493 The likely/unlikely profiler only looks at the conditions that
494 are annotated with a likely or unlikely macro.
496 The "all branch" profiler will profile every if-statement in the
497 kernel. This profiler will also enable the likely/unlikely
500 Either of the above profilers adds a bit of overhead to the system.
501 If unsure, choose "No branch profiling".
503 config BRANCH_PROFILE_NONE
504 bool "No branch profiling"
506 No branch profiling. Branch profiling adds a bit of overhead.
507 Only enable it if you want to analyse the branching behavior.
508 Otherwise keep it disabled.
510 config PROFILE_ANNOTATED_BRANCHES
511 bool "Trace likely/unlikely profiler"
512 select TRACE_BRANCH_PROFILING
514 This tracer profiles all likely and unlikely macros
515 in the kernel. It will display the results in:
517 /sys/kernel/debug/tracing/trace_stat/branch_annotated
519 Note: this will add a significant overhead; only turn this
520 on if you need to profile the system's use of these macros.
522 config PROFILE_ALL_BRANCHES
523 bool "Profile all if conditionals" if !FORTIFY_SOURCE
524 select TRACE_BRANCH_PROFILING
526 This tracer profiles all branch conditions. Every if ()
527 taken in the kernel is recorded whether it hit or miss.
528 The results will be displayed in:
530 /sys/kernel/debug/tracing/trace_stat/branch_all
532 This option also enables the likely/unlikely profiler.
534 This configuration, when enabled, will impose a great overhead
535 on the system. This should only be enabled when the system
536 is to be analyzed in much detail.
539 config TRACING_BRANCHES
542 Selected by tracers that will trace the likely and unlikely
543 conditions. This prevents the tracers themselves from being
544 profiled. Profiling the tracing infrastructure can only happen
545 when the likelys and unlikelys are not being traced.
548 bool "Trace likely/unlikely instances"
549 depends on TRACE_BRANCH_PROFILING
550 select TRACING_BRANCHES
552 This traces the events of likely and unlikely condition
553 calls in the kernel. The difference between this and the
554 "Trace likely/unlikely profiler" is that this is not a
555 histogram of the callers, but actually places the calling
556 events into a running trace buffer to see when and where the
557 events happened, as well as their results.
561 config BLK_DEV_IO_TRACE
562 bool "Support for tracing block IO actions"
568 select GENERIC_TRACER
571 Say Y here if you want to be able to trace the block layer actions
572 on a given queue. Tracing allows you to see any traffic happening
573 on a block device queue. For more information (and the userspace
574 support tools needed), fetch the blktrace tools from:
576 git://git.kernel.dk/blktrace.git
578 Tracing also is possible using the ftrace interface, e.g.:
580 echo 1 > /sys/block/sda/sda1/trace/enable
581 echo blk > /sys/kernel/debug/tracing/current_tracer
582 cat /sys/kernel/debug/tracing/trace_pipe
588 depends on HAVE_REGS_AND_STACK_ACCESS_API
589 bool "Enable kprobes-based dynamic events"
592 select DYNAMIC_EVENTS
595 This allows the user to add tracing events (similar to tracepoints)
596 on the fly via the ftrace interface. See
597 Documentation/trace/kprobetrace.rst for more details.
599 Those events can be inserted wherever kprobes can probe, and record
600 various register and memory values.
602 This option is also required by perf-probe subcommand of perf tools.
603 If you want to use perf tools, this option is strongly recommended.
605 config KPROBE_EVENTS_ON_NOTRACE
606 bool "Do NOT protect notrace function from kprobe events"
607 depends on KPROBE_EVENTS
608 depends on DYNAMIC_FTRACE
611 This is only for the developers who want to debug ftrace itself
614 If kprobes can use ftrace instead of breakpoint, ftrace related
615 functions are protected from kprobe-events to prevent an infinite
616 recursion or any unexpected execution path which leads to a kernel
619 This option disables such protection and allows you to put kprobe
620 events on ftrace functions for debugging ftrace by itself.
621 Note that this might let you shoot yourself in the foot.
626 bool "Enable uprobes-based dynamic events"
627 depends on ARCH_SUPPORTS_UPROBES
629 depends on PERF_EVENTS
632 select DYNAMIC_EVENTS
636 This allows the user to add tracing events on top of userspace
637 dynamic events (similar to tracepoints) on the fly via the trace
638 events interface. Those events can be inserted wherever uprobes
639 can probe, and record various registers.
640 This option is required if you plan to use perf-probe subcommand
641 of perf tools on user space applications.
644 depends on BPF_SYSCALL
645 depends on (KPROBE_EVENTS || UPROBE_EVENTS) && PERF_EVENTS
649 This allows the user to attach BPF programs to kprobe, uprobe, and
652 config DYNAMIC_EVENTS
658 config BPF_KPROBE_OVERRIDE
659 bool "Enable BPF programs to override a kprobed function"
660 depends on BPF_EVENTS
661 depends on FUNCTION_ERROR_INJECTION
664 Allows BPF to override the execution of a probed function and
665 set a different return value. This is used for error injection.
667 config FTRACE_MCOUNT_RECORD
669 depends on DYNAMIC_FTRACE
670 depends on HAVE_FTRACE_MCOUNT_RECORD
672 config FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
674 depends on FTRACE_MCOUNT_RECORD
676 config FTRACE_MCOUNT_USE_CC
678 depends on $(cc-option,-mrecord-mcount)
679 depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
680 depends on FTRACE_MCOUNT_RECORD
682 config FTRACE_MCOUNT_USE_OBJTOOL
684 depends on HAVE_OBJTOOL_MCOUNT
685 depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
686 depends on !FTRACE_MCOUNT_USE_CC
687 depends on FTRACE_MCOUNT_RECORD
689 config FTRACE_MCOUNT_USE_RECORDMCOUNT
691 depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
692 depends on !FTRACE_MCOUNT_USE_CC
693 depends on !FTRACE_MCOUNT_USE_OBJTOOL
694 depends on FTRACE_MCOUNT_RECORD
698 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
700 tracing_map is a special-purpose lock-free map for tracing,
701 separated out as a stand-alone facility in order to allow it
702 to be shared between multiple tracers. It isn't meant to be
703 generally used outside of that context, and is normally
704 selected by tracers that use it.
707 bool "Synthetic trace events"
709 select DYNAMIC_EVENTS
712 Synthetic events are user-defined trace events that can be
713 used to combine data from other trace events or in fact any
714 data source. Synthetic events can be generated indirectly
715 via the trace() action of histogram triggers or directly
716 by way of an in-kernel API.
718 See Documentation/trace/events.rst or
719 Documentation/trace/histogram.rst for details and examples.
724 bool "Histogram triggers"
725 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
728 select DYNAMIC_EVENTS
732 Hist triggers allow one or more arbitrary trace event fields
733 to be aggregated into hash tables and dumped to stdout by
734 reading a debugfs/tracefs file. They're useful for
735 gathering quick and dirty (though precise) summaries of
736 event activity as an initial guide for further investigation
737 using more advanced tools.
739 Inter-event tracing of quantities such as latencies is also
740 supported using hist triggers under this option.
742 See Documentation/trace/histogram.rst.
745 config TRACE_EVENT_INJECT
746 bool "Trace event injection"
749 Allow user-space to inject a specific trace event into the ring
750 buffer. This is mainly used for testing purpose.
754 config TRACEPOINT_BENCHMARK
755 bool "Add tracepoint that benchmarks tracepoints"
757 This option creates the tracepoint "benchmark:benchmark_event".
758 When the tracepoint is enabled, it kicks off a kernel thread that
759 goes into an infinite loop (calling cond_resched() to let other tasks
760 run), and calls the tracepoint. Each iteration will record the time
761 it took to write to the tracepoint and the next iteration that
762 data will be passed to the tracepoint itself. That is, the tracepoint
763 will report the time it took to do the previous tracepoint.
764 The string written to the tracepoint is a static string of 128 bytes
765 to keep the time the same. The initial string is simply a write of
766 "START". The second string records the cold cache time of the first
767 write which is not added to the rest of the calculations.
769 As it is a tight loop, it benchmarks as hot cache. That's fine because
770 we care most about hot paths that are probably in cache already.
772 An example of the output:
775 first=3672 [COLD CACHED]
776 last=632 first=3672 max=632 min=632 avg=316 std=446 std^2=199712
777 last=278 first=3672 max=632 min=278 avg=303 std=316 std^2=100337
778 last=277 first=3672 max=632 min=277 avg=296 std=258 std^2=67064
779 last=273 first=3672 max=632 min=273 avg=292 std=224 std^2=50411
780 last=273 first=3672 max=632 min=273 avg=288 std=200 std^2=40389
781 last=281 first=3672 max=632 min=273 avg=287 std=183 std^2=33666
784 config RING_BUFFER_BENCHMARK
785 tristate "Ring buffer benchmark stress tester"
786 depends on RING_BUFFER
788 This option creates a test to stress the ring buffer and benchmark it.
789 It creates its own ring buffer such that it will not interfere with
790 any other users of the ring buffer (such as ftrace). It then creates
791 a producer and consumer that will run for 10 seconds and sleep for
792 10 seconds. Each interval it will print out the number of events
793 it recorded and give a rough estimate of how long each iteration took.
795 It does not disable interrupts or raise its priority, so it may be
796 affected by processes that are running.
800 config TRACE_EVAL_MAP_FILE
801 bool "Show eval mappings for trace events"
804 The "print fmt" of the trace events will show the enum/sizeof names
805 instead of their values. This can cause problems for user space tools
806 that use this string to parse the raw data as user space does not know
807 how to convert the string to its value.
809 To fix this, there's a special macro in the kernel that can be used
810 to convert an enum/sizeof into its value. If this macro is used, then
811 the print fmt strings will be converted to their values.
813 If something does not get converted properly, this option can be
814 used to show what enums/sizeof the kernel tried to convert.
816 This option is for debugging the conversions. A file is created
817 in the tracing directory called "eval_map" that will show the
818 names matched with their values and what trace event system they
821 Normally, the mapping of the strings to values will be freed after
822 boot up or module load. With this option, they will not be freed, as
823 they are needed for the "eval_map" file. Enabling this option will
824 increase the memory footprint of the running kernel.
828 config FTRACE_RECORD_RECURSION
829 bool "Record functions that recurse in function tracing"
830 depends on FUNCTION_TRACER
832 All callbacks that attach to the function tracing have some sort
833 of protection against recursion. Even though the protection exists,
834 it adds overhead. This option will create a file in the tracefs
835 file system called "recursed_functions" that will list the functions
836 that triggered a recursion.
838 This will add more overhead to cases that have recursion.
842 config FTRACE_RECORD_RECURSION_SIZE
843 int "Max number of recursed functions to record"
845 depends on FTRACE_RECORD_RECURSION
847 This defines the limit of number of functions that can be
848 listed in the "recursed_functions" file, that lists all
849 the functions that caused a recursion to happen.
850 This file can be reset, but the limit can not change in
853 config RING_BUFFER_RECORD_RECURSION
854 bool "Record functions that recurse in the ring buffer"
855 depends on FTRACE_RECORD_RECURSION
856 # default y, because it is coupled with FTRACE_RECORD_RECURSION
859 The ring buffer has its own internal recursion. Although when
860 recursion happens it wont cause harm because of the protection,
861 but it does cause an unwanted overhead. Enabling this option will
862 place where recursion was detected into the ftrace "recursed_functions"
865 This will add more overhead to cases that have recursion.
867 config GCOV_PROFILE_FTRACE
868 bool "Enable GCOV profiling on ftrace subsystem"
869 depends on GCOV_KERNEL
871 Enable GCOV profiling on ftrace subsystem for checking
872 which functions/lines are tested.
876 Note that on a kernel compiled with this config, ftrace will
877 run significantly slower.
879 config FTRACE_SELFTEST
882 config FTRACE_STARTUP_TEST
883 bool "Perform a startup test on ftrace"
884 depends on GENERIC_TRACER
885 select FTRACE_SELFTEST
887 This option performs a series of startup tests on ftrace. On bootup
888 a series of tests are made to verify that the tracer is
889 functioning properly. It will do tests on all the configured
892 config EVENT_TRACE_STARTUP_TEST
893 bool "Run selftest on trace events"
894 depends on FTRACE_STARTUP_TEST
897 This option performs a test on all trace events in the system.
898 It basically just enables each event and runs some code that
899 will trigger events (not necessarily the event it enables)
900 This may take some time run as there are a lot of events.
902 config EVENT_TRACE_TEST_SYSCALLS
903 bool "Run selftest on syscall events"
904 depends on EVENT_TRACE_STARTUP_TEST
906 This option will also enable testing every syscall event.
907 It only enables the event and disables it and runs various loads
908 with the event enabled. This adds a bit more time for kernel boot
909 up since it runs this on every system call defined.
911 TBD - enable a way to actually call the syscalls as we test their
914 config RING_BUFFER_STARTUP_TEST
915 bool "Ring buffer startup self test"
916 depends on RING_BUFFER
918 Run a simple self test on the ring buffer on boot up. Late in the
919 kernel boot sequence, the test will start that kicks off
920 a thread per cpu. Each thread will write various size events
921 into the ring buffer. Another thread is created to send IPIs
922 to each of the threads, where the IPI handler will also write
923 to the ring buffer, to test/stress the nesting ability.
924 If any anomalies are discovered, a warning will be displayed
925 and all ring buffers will be disabled.
927 The test runs for 10 seconds. This will slow your boot time
928 by at least 10 more seconds.
930 At the end of the test, statics and more checks are done.
931 It will output the stats of each per cpu buffer. What
932 was written, the sizes, what was read, what was lost, and
933 other similar details.
937 config RING_BUFFER_VALIDATE_TIME_DELTAS
938 bool "Verify ring buffer time stamp deltas"
939 depends on RING_BUFFER
941 This will audit the time stamps on the ring buffer sub
942 buffer to make sure that all the time deltas for the
943 events on a sub buffer matches the current time stamp.
944 This audit is performed for every event that is not
945 interrupted, or interrupting another event. A check
946 is also made when traversing sub buffers to make sure
947 that all the deltas on the previous sub buffer do not
948 add up to be greater than the current time stamp.
950 NOTE: This adds significant overhead to recording of events,
951 and should only be used to test the logic of the ring buffer.
952 Do not use it on production systems.
954 Only say Y if you understand what this does, and you
955 still want it enabled. Otherwise say N
957 config MMIOTRACE_TEST
958 tristate "Test module for mmiotrace"
959 depends on MMIOTRACE && m
961 This is a dumb module for testing mmiotrace. It is very dangerous
962 as it will write garbage to IO memory starting at a given address.
963 However, it should be safe to use on e.g. unused portion of VRAM.
965 Say N, unless you absolutely know what you are doing.
967 config PREEMPTIRQ_DELAY_TEST
968 tristate "Test module to create a preempt / IRQ disable delay thread to test latency tracers"
971 Select this option to build a test module that can help test latency
972 tracers by executing a preempt or irq disable section with a user
973 configurable delay. The module busy waits for the duration of the
976 For example, the following invocation generates a burst of three
977 irq-disabled critical sections for 500us:
978 modprobe preemptirq_delay_test test_mode=irq delay=500 burst_size=3
980 What's more, if you want to attach the test on the cpu which the latency
981 tracer is running on, specify cpu_affinity=cpu_num at the end of the
986 config SYNTH_EVENT_GEN_TEST
987 tristate "Test module for in-kernel synthetic event generation"
988 depends on SYNTH_EVENTS
990 This option creates a test module to check the base
991 functionality of in-kernel synthetic event definition and
994 To test, insert the module, and then check the trace buffer
995 for the generated sample events.
999 config KPROBE_EVENT_GEN_TEST
1000 tristate "Test module for in-kernel kprobe event generation"
1001 depends on KPROBE_EVENTS
1003 This option creates a test module to check the base
1004 functionality of in-kernel kprobe event definition.
1006 To test, insert the module, and then check the trace buffer
1007 for the generated kprobe events.
1011 config HIST_TRIGGERS_DEBUG
1012 bool "Hist trigger debug support"
1013 depends on HIST_TRIGGERS
1015 Add "hist_debug" file for each event, which when read will
1016 dump out a bunch of internal details about the hist triggers
1017 defined on that event.
1019 The hist_debug file serves a couple of purposes:
1021 - Helps developers verify that nothing is broken.
1023 - Provides educational information to support the details
1024 of the hist trigger internals as described by
1025 Documentation/trace/histogram-design.rst.
1027 The hist_debug output only covers the data structures
1028 related to the histogram definitions themselves and doesn't
1029 display the internals of map buckets or variable values of
1036 endif # TRACING_SUPPORT
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