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
140 depends on TRACING_SUPPORT
141 default y if DEBUG_KERNEL
143 Enable the kernel tracing infrastructure.
147 config BOOTTIME_TRACING
148 bool "Boot-time Tracing support"
152 Enable developer to setup ftrace subsystem via supplemental
153 kernel cmdline at boot time for debugging (tracing) driver
154 initialization and boot process.
156 config FUNCTION_TRACER
157 bool "Kernel Function Tracer"
158 depends on HAVE_FUNCTION_TRACER
160 select GENERIC_TRACER
161 select CONTEXT_SWITCH_TRACER
163 select TASKS_RCU if PREEMPTION
164 select TASKS_RUDE_RCU
166 Enable the kernel to trace every kernel function. This is done
167 by using a compiler feature to insert a small, 5-byte No-Operation
168 instruction at the beginning of every kernel function, which NOP
169 sequence is then dynamically patched into a tracer call when
170 tracing is enabled by the administrator. If it's runtime disabled
171 (the bootup default), then the overhead of the instructions is very
172 small and not measurable even in micro-benchmarks.
174 config FUNCTION_GRAPH_TRACER
175 bool "Kernel Function Graph Tracer"
176 depends on HAVE_FUNCTION_GRAPH_TRACER
177 depends on FUNCTION_TRACER
178 depends on !X86_32 || !CC_OPTIMIZE_FOR_SIZE
181 Enable the kernel to trace a function at both its return
183 Its first purpose is to trace the duration of functions and
184 draw a call graph for each thread with some information like
185 the return value. This is done by setting the current return
186 address on the current task structure into a stack of calls.
188 config DYNAMIC_FTRACE
189 bool "enable/disable function tracing dynamically"
190 depends on FUNCTION_TRACER
191 depends on HAVE_DYNAMIC_FTRACE
194 This option will modify all the calls to function tracing
195 dynamically (will patch them out of the binary image and
196 replace them with a No-Op instruction) on boot up. During
197 compile time, a table is made of all the locations that ftrace
198 can function trace, and this table is linked into the kernel
199 image. When this is enabled, functions can be individually
200 enabled, and the functions not enabled will not affect
201 performance of the system.
203 See the files in /sys/kernel/debug/tracing:
204 available_filter_functions
208 This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but
209 otherwise has native performance as long as no tracing is active.
211 config DYNAMIC_FTRACE_WITH_REGS
213 depends on DYNAMIC_FTRACE
214 depends on HAVE_DYNAMIC_FTRACE_WITH_REGS
216 config DYNAMIC_FTRACE_WITH_DIRECT_CALLS
218 depends on DYNAMIC_FTRACE_WITH_REGS
219 depends on HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
221 config DYNAMIC_FTRACE_WITH_ARGS
223 depends on DYNAMIC_FTRACE
224 depends on HAVE_DYNAMIC_FTRACE_WITH_ARGS
226 config FUNCTION_PROFILER
227 bool "Kernel function profiler"
228 depends on FUNCTION_TRACER
231 This option enables the kernel function profiler. A file is created
232 in debugfs called function_profile_enabled which defaults to zero.
233 When a 1 is echoed into this file profiling begins, and when a
234 zero is entered, profiling stops. A "functions" file is created in
235 the trace_stat directory; this file shows the list of functions that
236 have been hit and their counters.
241 bool "Trace max stack"
242 depends on HAVE_FUNCTION_TRACER
243 select FUNCTION_TRACER
247 This special tracer records the maximum stack footprint of the
248 kernel and displays it in /sys/kernel/debug/tracing/stack_trace.
250 This tracer works by hooking into every function call that the
251 kernel executes, and keeping a maximum stack depth value and
252 stack-trace saved. If this is configured with DYNAMIC_FTRACE
253 then it will not have any overhead while the stack tracer
256 To enable the stack tracer on bootup, pass in 'stacktrace'
257 on the kernel command line.
259 The stack tracer can also be enabled or disabled via the
260 sysctl kernel.stack_tracer_enabled
264 config TRACE_PREEMPT_TOGGLE
267 Enables hooks which will be called when preemption is first disabled,
270 config IRQSOFF_TRACER
271 bool "Interrupts-off Latency Tracer"
273 depends on TRACE_IRQFLAGS_SUPPORT
274 select TRACE_IRQFLAGS
275 select GENERIC_TRACER
276 select TRACER_MAX_TRACE
277 select RING_BUFFER_ALLOW_SWAP
278 select TRACER_SNAPSHOT
279 select TRACER_SNAPSHOT_PER_CPU_SWAP
281 This option measures the time spent in irqs-off critical
282 sections, with microsecond accuracy.
284 The default measurement method is a maximum search, which is
285 disabled by default and can be runtime (re-)started
288 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
290 (Note that kernel size and overhead increase with this option
291 enabled. This option and the preempt-off timing option can be
292 used together or separately.)
294 config PREEMPT_TRACER
295 bool "Preemption-off Latency Tracer"
297 depends on PREEMPTION
298 select GENERIC_TRACER
299 select TRACER_MAX_TRACE
300 select RING_BUFFER_ALLOW_SWAP
301 select TRACER_SNAPSHOT
302 select TRACER_SNAPSHOT_PER_CPU_SWAP
303 select TRACE_PREEMPT_TOGGLE
305 This option measures the time spent in preemption-off critical
306 sections, with microsecond accuracy.
308 The default measurement method is a maximum search, which is
309 disabled by default and can be runtime (re-)started
312 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
314 (Note that kernel size and overhead increase with this option
315 enabled. This option and the irqs-off timing option can be
316 used together or separately.)
319 bool "Scheduling Latency Tracer"
320 select GENERIC_TRACER
321 select CONTEXT_SWITCH_TRACER
322 select TRACER_MAX_TRACE
323 select TRACER_SNAPSHOT
325 This tracer tracks the latency of the highest priority task
326 to be scheduled in, starting from the point it has woken up.
329 bool "Tracer to detect hardware latencies (like SMIs)"
330 select GENERIC_TRACER
332 This tracer, when enabled will create one or more kernel threads,
333 depending on what the cpumask file is set to, which each thread
334 spinning in a loop looking for interruptions caused by
335 something other than the kernel. For example, if a
336 System Management Interrupt (SMI) takes a noticeable amount of
337 time, this tracer will detect it. This is useful for testing
338 if a system is reliable for Real Time tasks.
340 Some files are created in the tracing directory when this
343 hwlat_detector/width - time in usecs for how long to spin for
344 hwlat_detector/window - time in usecs between the start of each
347 A kernel thread is created that will spin with interrupts disabled
348 for "width" microseconds in every "window" cycle. It will not spin
349 for "window - width" microseconds, where the system can
352 The output will appear in the trace and trace_pipe files.
354 When the tracer is not running, it has no affect on the system,
355 but when it is running, it can cause the system to be
356 periodically non responsive. Do not run this tracer on a
359 To enable this tracer, echo in "hwlat" into the current_tracer
360 file. Every time a latency is greater than tracing_thresh, it will
361 be recorded into the ring buffer.
363 config OSNOISE_TRACER
364 bool "OS Noise tracer"
365 select GENERIC_TRACER
367 In the context of high-performance computing (HPC), the Operating
368 System Noise (osnoise) refers to the interference experienced by an
369 application due to activities inside the operating system. In the
370 context of Linux, NMIs, IRQs, SoftIRQs, and any other system thread
371 can cause noise to the system. Moreover, hardware-related jobs can
372 also cause noise, for example, via SMIs.
374 The osnoise tracer leverages the hwlat_detector by running a similar
375 loop with preemption, SoftIRQs and IRQs enabled, thus allowing all
376 the sources of osnoise during its execution. The osnoise tracer takes
377 note of the entry and exit point of any source of interferences,
378 increasing a per-cpu interference counter. It saves an interference
379 counter for each source of interference. The interference counter for
380 NMI, IRQs, SoftIRQs, and threads is increased anytime the tool
381 observes these interferences' entry events. When a noise happens
382 without any interference from the operating system level, the
383 hardware noise counter increases, pointing to a hardware-related
384 noise. In this way, osnoise can account for any source of
385 interference. At the end of the period, the osnoise tracer prints
386 the sum of all noise, the max single noise, the percentage of CPU
387 available for the thread, and the counters for the noise sources.
389 In addition to the tracer, a set of tracepoints were added to
390 facilitate the identification of the osnoise source.
392 The output will appear in the trace and trace_pipe files.
394 To enable this tracer, echo in "osnoise" into the current_tracer
397 config TIMERLAT_TRACER
398 bool "Timerlat tracer"
399 select OSNOISE_TRACER
400 select GENERIC_TRACER
402 The timerlat tracer aims to help the preemptive kernel developers
403 to find sources of wakeup latencies of real-time threads.
405 The tracer creates a per-cpu kernel thread with real-time priority.
406 The tracer thread sets a periodic timer to wakeup itself, and goes
407 to sleep waiting for the timer to fire. At the wakeup, the thread
408 then computes a wakeup latency value as the difference between
409 the current time and the absolute time that the timer was set
412 The tracer prints two lines at every activation. The first is the
413 timer latency observed at the hardirq context before the
414 activation of the thread. The second is the timer latency observed
415 by the thread, which is the same level that cyclictest reports. The
416 ACTIVATION ID field serves to relate the irq execution to its
417 respective thread execution.
419 The tracer is build on top of osnoise tracer, and the osnoise:
420 events can be used to trace the source of interference from NMI,
421 IRQs and other threads. It also enables the capture of the
422 stacktrace at the IRQ context, which helps to identify the code
423 path that can cause thread delay.
426 bool "Memory mapped IO tracing"
427 depends on HAVE_MMIOTRACE_SUPPORT && PCI
428 select GENERIC_TRACER
430 Mmiotrace traces Memory Mapped I/O access and is meant for
431 debugging and reverse engineering. It is called from the ioremap
432 implementation and works via page faults. Tracing is disabled by
433 default and can be enabled at run-time.
435 See Documentation/trace/mmiotrace.rst.
436 If you are not helping to develop drivers, say N.
438 config ENABLE_DEFAULT_TRACERS
439 bool "Trace process context switches and events"
440 depends on !GENERIC_TRACER
443 This tracer hooks to various trace points in the kernel,
444 allowing the user to pick and choose which trace point they
445 want to trace. It also includes the sched_switch tracer plugin.
447 config FTRACE_SYSCALLS
448 bool "Trace syscalls"
449 depends on HAVE_SYSCALL_TRACEPOINTS
450 select GENERIC_TRACER
453 Basic tracer to catch the syscall entry and exit events.
455 config TRACER_SNAPSHOT
456 bool "Create a snapshot trace buffer"
457 select TRACER_MAX_TRACE
459 Allow tracing users to take snapshot of the current buffer using the
460 ftrace interface, e.g.:
462 echo 1 > /sys/kernel/debug/tracing/snapshot
465 config TRACER_SNAPSHOT_PER_CPU_SWAP
466 bool "Allow snapshot to swap per CPU"
467 depends on TRACER_SNAPSHOT
468 select RING_BUFFER_ALLOW_SWAP
470 Allow doing a snapshot of a single CPU buffer instead of a
471 full swap (all buffers). If this is set, then the following is
474 echo 1 > /sys/kernel/debug/tracing/per_cpu/cpu2/snapshot
476 After which, only the tracing buffer for CPU 2 was swapped with
477 the main tracing buffer, and the other CPU buffers remain the same.
479 When this is enabled, this adds a little more overhead to the
480 trace recording, as it needs to add some checks to synchronize
481 recording with swaps. But this does not affect the performance
482 of the overall system. This is enabled by default when the preempt
483 or irq latency tracers are enabled, as those need to swap as well
484 and already adds the overhead (plus a lot more).
486 config TRACE_BRANCH_PROFILING
488 select GENERIC_TRACER
491 prompt "Branch Profiling"
492 default BRANCH_PROFILE_NONE
494 The branch profiling is a software profiler. It will add hooks
495 into the C conditionals to test which path a branch takes.
497 The likely/unlikely profiler only looks at the conditions that
498 are annotated with a likely or unlikely macro.
500 The "all branch" profiler will profile every if-statement in the
501 kernel. This profiler will also enable the likely/unlikely
504 Either of the above profilers adds a bit of overhead to the system.
505 If unsure, choose "No branch profiling".
507 config BRANCH_PROFILE_NONE
508 bool "No branch profiling"
510 No branch profiling. Branch profiling adds a bit of overhead.
511 Only enable it if you want to analyse the branching behavior.
512 Otherwise keep it disabled.
514 config PROFILE_ANNOTATED_BRANCHES
515 bool "Trace likely/unlikely profiler"
516 select TRACE_BRANCH_PROFILING
518 This tracer profiles all likely and unlikely macros
519 in the kernel. It will display the results in:
521 /sys/kernel/debug/tracing/trace_stat/branch_annotated
523 Note: this will add a significant overhead; only turn this
524 on if you need to profile the system's use of these macros.
526 config PROFILE_ALL_BRANCHES
527 bool "Profile all if conditionals" if !FORTIFY_SOURCE
528 select TRACE_BRANCH_PROFILING
530 This tracer profiles all branch conditions. Every if ()
531 taken in the kernel is recorded whether it hit or miss.
532 The results will be displayed in:
534 /sys/kernel/debug/tracing/trace_stat/branch_all
536 This option also enables the likely/unlikely profiler.
538 This configuration, when enabled, will impose a great overhead
539 on the system. This should only be enabled when the system
540 is to be analyzed in much detail.
543 config TRACING_BRANCHES
546 Selected by tracers that will trace the likely and unlikely
547 conditions. This prevents the tracers themselves from being
548 profiled. Profiling the tracing infrastructure can only happen
549 when the likelys and unlikelys are not being traced.
552 bool "Trace likely/unlikely instances"
553 depends on TRACE_BRANCH_PROFILING
554 select TRACING_BRANCHES
556 This traces the events of likely and unlikely condition
557 calls in the kernel. The difference between this and the
558 "Trace likely/unlikely profiler" is that this is not a
559 histogram of the callers, but actually places the calling
560 events into a running trace buffer to see when and where the
561 events happened, as well as their results.
565 config BLK_DEV_IO_TRACE
566 bool "Support for tracing block IO actions"
572 select GENERIC_TRACER
575 Say Y here if you want to be able to trace the block layer actions
576 on a given queue. Tracing allows you to see any traffic happening
577 on a block device queue. For more information (and the userspace
578 support tools needed), fetch the blktrace tools from:
580 git://git.kernel.dk/blktrace.git
582 Tracing also is possible using the ftrace interface, e.g.:
584 echo 1 > /sys/block/sda/sda1/trace/enable
585 echo blk > /sys/kernel/debug/tracing/current_tracer
586 cat /sys/kernel/debug/tracing/trace_pipe
592 depends on HAVE_REGS_AND_STACK_ACCESS_API
593 bool "Enable kprobes-based dynamic events"
596 select DYNAMIC_EVENTS
599 This allows the user to add tracing events (similar to tracepoints)
600 on the fly via the ftrace interface. See
601 Documentation/trace/kprobetrace.rst for more details.
603 Those events can be inserted wherever kprobes can probe, and record
604 various register and memory values.
606 This option is also required by perf-probe subcommand of perf tools.
607 If you want to use perf tools, this option is strongly recommended.
609 config KPROBE_EVENTS_ON_NOTRACE
610 bool "Do NOT protect notrace function from kprobe events"
611 depends on KPROBE_EVENTS
612 depends on DYNAMIC_FTRACE
615 This is only for the developers who want to debug ftrace itself
618 If kprobes can use ftrace instead of breakpoint, ftrace related
619 functions are protected from kprobe-events to prevent an infinite
620 recursion or any unexpected execution path which leads to a kernel
623 This option disables such protection and allows you to put kprobe
624 events on ftrace functions for debugging ftrace by itself.
625 Note that this might let you shoot yourself in the foot.
630 bool "Enable uprobes-based dynamic events"
631 depends on ARCH_SUPPORTS_UPROBES
633 depends on PERF_EVENTS
636 select DYNAMIC_EVENTS
640 This allows the user to add tracing events on top of userspace
641 dynamic events (similar to tracepoints) on the fly via the trace
642 events interface. Those events can be inserted wherever uprobes
643 can probe, and record various registers.
644 This option is required if you plan to use perf-probe subcommand
645 of perf tools on user space applications.
648 depends on BPF_SYSCALL
649 depends on (KPROBE_EVENTS || UPROBE_EVENTS) && PERF_EVENTS
653 This allows the user to attach BPF programs to kprobe, uprobe, and
656 config DYNAMIC_EVENTS
662 config BPF_KPROBE_OVERRIDE
663 bool "Enable BPF programs to override a kprobed function"
664 depends on BPF_EVENTS
665 depends on FUNCTION_ERROR_INJECTION
668 Allows BPF to override the execution of a probed function and
669 set a different return value. This is used for error injection.
671 config FTRACE_MCOUNT_RECORD
673 depends on DYNAMIC_FTRACE
674 depends on HAVE_FTRACE_MCOUNT_RECORD
676 config FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
678 depends on FTRACE_MCOUNT_RECORD
680 config FTRACE_MCOUNT_USE_CC
682 depends on $(cc-option,-mrecord-mcount)
683 depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
684 depends on FTRACE_MCOUNT_RECORD
686 config FTRACE_MCOUNT_USE_OBJTOOL
688 depends on HAVE_OBJTOOL_MCOUNT
689 depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
690 depends on !FTRACE_MCOUNT_USE_CC
691 depends on FTRACE_MCOUNT_RECORD
693 config FTRACE_MCOUNT_USE_RECORDMCOUNT
695 depends on !FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
696 depends on !FTRACE_MCOUNT_USE_CC
697 depends on !FTRACE_MCOUNT_USE_OBJTOOL
698 depends on FTRACE_MCOUNT_RECORD
702 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
704 tracing_map is a special-purpose lock-free map for tracing,
705 separated out as a stand-alone facility in order to allow it
706 to be shared between multiple tracers. It isn't meant to be
707 generally used outside of that context, and is normally
708 selected by tracers that use it.
711 bool "Synthetic trace events"
713 select DYNAMIC_EVENTS
716 Synthetic events are user-defined trace events that can be
717 used to combine data from other trace events or in fact any
718 data source. Synthetic events can be generated indirectly
719 via the trace() action of histogram triggers or directly
720 by way of an in-kernel API.
722 See Documentation/trace/events.rst or
723 Documentation/trace/histogram.rst for details and examples.
728 bool "Histogram triggers"
729 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
732 select DYNAMIC_EVENTS
736 Hist triggers allow one or more arbitrary trace event fields
737 to be aggregated into hash tables and dumped to stdout by
738 reading a debugfs/tracefs file. They're useful for
739 gathering quick and dirty (though precise) summaries of
740 event activity as an initial guide for further investigation
741 using more advanced tools.
743 Inter-event tracing of quantities such as latencies is also
744 supported using hist triggers under this option.
746 See Documentation/trace/histogram.rst.
749 config TRACE_EVENT_INJECT
750 bool "Trace event injection"
753 Allow user-space to inject a specific trace event into the ring
754 buffer. This is mainly used for testing purpose.
758 config TRACEPOINT_BENCHMARK
759 bool "Add tracepoint that benchmarks tracepoints"
761 This option creates the tracepoint "benchmark:benchmark_event".
762 When the tracepoint is enabled, it kicks off a kernel thread that
763 goes into an infinite loop (calling cond_resched() to let other tasks
764 run), and calls the tracepoint. Each iteration will record the time
765 it took to write to the tracepoint and the next iteration that
766 data will be passed to the tracepoint itself. That is, the tracepoint
767 will report the time it took to do the previous tracepoint.
768 The string written to the tracepoint is a static string of 128 bytes
769 to keep the time the same. The initial string is simply a write of
770 "START". The second string records the cold cache time of the first
771 write which is not added to the rest of the calculations.
773 As it is a tight loop, it benchmarks as hot cache. That's fine because
774 we care most about hot paths that are probably in cache already.
776 An example of the output:
779 first=3672 [COLD CACHED]
780 last=632 first=3672 max=632 min=632 avg=316 std=446 std^2=199712
781 last=278 first=3672 max=632 min=278 avg=303 std=316 std^2=100337
782 last=277 first=3672 max=632 min=277 avg=296 std=258 std^2=67064
783 last=273 first=3672 max=632 min=273 avg=292 std=224 std^2=50411
784 last=273 first=3672 max=632 min=273 avg=288 std=200 std^2=40389
785 last=281 first=3672 max=632 min=273 avg=287 std=183 std^2=33666
788 config RING_BUFFER_BENCHMARK
789 tristate "Ring buffer benchmark stress tester"
790 depends on RING_BUFFER
792 This option creates a test to stress the ring buffer and benchmark it.
793 It creates its own ring buffer such that it will not interfere with
794 any other users of the ring buffer (such as ftrace). It then creates
795 a producer and consumer that will run for 10 seconds and sleep for
796 10 seconds. Each interval it will print out the number of events
797 it recorded and give a rough estimate of how long each iteration took.
799 It does not disable interrupts or raise its priority, so it may be
800 affected by processes that are running.
804 config TRACE_EVAL_MAP_FILE
805 bool "Show eval mappings for trace events"
808 The "print fmt" of the trace events will show the enum/sizeof names
809 instead of their values. This can cause problems for user space tools
810 that use this string to parse the raw data as user space does not know
811 how to convert the string to its value.
813 To fix this, there's a special macro in the kernel that can be used
814 to convert an enum/sizeof into its value. If this macro is used, then
815 the print fmt strings will be converted to their values.
817 If something does not get converted properly, this option can be
818 used to show what enums/sizeof the kernel tried to convert.
820 This option is for debugging the conversions. A file is created
821 in the tracing directory called "eval_map" that will show the
822 names matched with their values and what trace event system they
825 Normally, the mapping of the strings to values will be freed after
826 boot up or module load. With this option, they will not be freed, as
827 they are needed for the "eval_map" file. Enabling this option will
828 increase the memory footprint of the running kernel.
832 config FTRACE_RECORD_RECURSION
833 bool "Record functions that recurse in function tracing"
834 depends on FUNCTION_TRACER
836 All callbacks that attach to the function tracing have some sort
837 of protection against recursion. Even though the protection exists,
838 it adds overhead. This option will create a file in the tracefs
839 file system called "recursed_functions" that will list the functions
840 that triggered a recursion.
842 This will add more overhead to cases that have recursion.
846 config FTRACE_RECORD_RECURSION_SIZE
847 int "Max number of recursed functions to record"
849 depends on FTRACE_RECORD_RECURSION
851 This defines the limit of number of functions that can be
852 listed in the "recursed_functions" file, that lists all
853 the functions that caused a recursion to happen.
854 This file can be reset, but the limit can not change in
857 config RING_BUFFER_RECORD_RECURSION
858 bool "Record functions that recurse in the ring buffer"
859 depends on FTRACE_RECORD_RECURSION
860 # default y, because it is coupled with FTRACE_RECORD_RECURSION
863 The ring buffer has its own internal recursion. Although when
864 recursion happens it wont cause harm because of the protection,
865 but it does cause an unwanted overhead. Enabling this option will
866 place where recursion was detected into the ftrace "recursed_functions"
869 This will add more overhead to cases that have recursion.
871 config GCOV_PROFILE_FTRACE
872 bool "Enable GCOV profiling on ftrace subsystem"
873 depends on GCOV_KERNEL
875 Enable GCOV profiling on ftrace subsystem for checking
876 which functions/lines are tested.
880 Note that on a kernel compiled with this config, ftrace will
881 run significantly slower.
883 config FTRACE_SELFTEST
886 config FTRACE_STARTUP_TEST
887 bool "Perform a startup test on ftrace"
888 depends on GENERIC_TRACER
889 select FTRACE_SELFTEST
891 This option performs a series of startup tests on ftrace. On bootup
892 a series of tests are made to verify that the tracer is
893 functioning properly. It will do tests on all the configured
896 config EVENT_TRACE_STARTUP_TEST
897 bool "Run selftest on trace events"
898 depends on FTRACE_STARTUP_TEST
901 This option performs a test on all trace events in the system.
902 It basically just enables each event and runs some code that
903 will trigger events (not necessarily the event it enables)
904 This may take some time run as there are a lot of events.
906 config EVENT_TRACE_TEST_SYSCALLS
907 bool "Run selftest on syscall events"
908 depends on EVENT_TRACE_STARTUP_TEST
910 This option will also enable testing every syscall event.
911 It only enables the event and disables it and runs various loads
912 with the event enabled. This adds a bit more time for kernel boot
913 up since it runs this on every system call defined.
915 TBD - enable a way to actually call the syscalls as we test their
918 config RING_BUFFER_STARTUP_TEST
919 bool "Ring buffer startup self test"
920 depends on RING_BUFFER
922 Run a simple self test on the ring buffer on boot up. Late in the
923 kernel boot sequence, the test will start that kicks off
924 a thread per cpu. Each thread will write various size events
925 into the ring buffer. Another thread is created to send IPIs
926 to each of the threads, where the IPI handler will also write
927 to the ring buffer, to test/stress the nesting ability.
928 If any anomalies are discovered, a warning will be displayed
929 and all ring buffers will be disabled.
931 The test runs for 10 seconds. This will slow your boot time
932 by at least 10 more seconds.
934 At the end of the test, statics and more checks are done.
935 It will output the stats of each per cpu buffer. What
936 was written, the sizes, what was read, what was lost, and
937 other similar details.
941 config RING_BUFFER_VALIDATE_TIME_DELTAS
942 bool "Verify ring buffer time stamp deltas"
943 depends on RING_BUFFER
945 This will audit the time stamps on the ring buffer sub
946 buffer to make sure that all the time deltas for the
947 events on a sub buffer matches the current time stamp.
948 This audit is performed for every event that is not
949 interrupted, or interrupting another event. A check
950 is also made when traversing sub buffers to make sure
951 that all the deltas on the previous sub buffer do not
952 add up to be greater than the current time stamp.
954 NOTE: This adds significant overhead to recording of events,
955 and should only be used to test the logic of the ring buffer.
956 Do not use it on production systems.
958 Only say Y if you understand what this does, and you
959 still want it enabled. Otherwise say N
961 config MMIOTRACE_TEST
962 tristate "Test module for mmiotrace"
963 depends on MMIOTRACE && m
965 This is a dumb module for testing mmiotrace. It is very dangerous
966 as it will write garbage to IO memory starting at a given address.
967 However, it should be safe to use on e.g. unused portion of VRAM.
969 Say N, unless you absolutely know what you are doing.
971 config PREEMPTIRQ_DELAY_TEST
972 tristate "Test module to create a preempt / IRQ disable delay thread to test latency tracers"
975 Select this option to build a test module that can help test latency
976 tracers by executing a preempt or irq disable section with a user
977 configurable delay. The module busy waits for the duration of the
980 For example, the following invocation generates a burst of three
981 irq-disabled critical sections for 500us:
982 modprobe preemptirq_delay_test test_mode=irq delay=500 burst_size=3
984 What's more, if you want to attach the test on the cpu which the latency
985 tracer is running on, specify cpu_affinity=cpu_num at the end of the
990 config SYNTH_EVENT_GEN_TEST
991 tristate "Test module for in-kernel synthetic event generation"
992 depends on SYNTH_EVENTS
994 This option creates a test module to check the base
995 functionality of in-kernel synthetic event definition and
998 To test, insert the module, and then check the trace buffer
999 for the generated sample events.
1003 config KPROBE_EVENT_GEN_TEST
1004 tristate "Test module for in-kernel kprobe event generation"
1005 depends on KPROBE_EVENTS
1007 This option creates a test module to check the base
1008 functionality of in-kernel kprobe event definition.
1010 To test, insert the module, and then check the trace buffer
1011 for the generated kprobe events.
1015 config HIST_TRIGGERS_DEBUG
1016 bool "Hist trigger debug support"
1017 depends on HIST_TRIGGERS
1019 Add "hist_debug" file for each event, which when read will
1020 dump out a bunch of internal details about the hist triggers
1021 defined on that event.
1023 The hist_debug file serves a couple of purposes:
1025 - Helps developers verify that nothing is broken.
1027 - Provides educational information to support the details
1028 of the hist trigger internals as described by
1029 Documentation/trace/histogram-design.rst.
1031 The hist_debug output only covers the data structures
1032 related to the histogram definitions themselves and doesn't
1033 display the internals of map buckets or variable values of