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Linux/kernel/trace/Kconfig

  1 #
  2 # Architectures that offer an FUNCTION_TRACER implementation should
  3 #  select HAVE_FUNCTION_TRACER:
  4 #
  5 
  6 config USER_STACKTRACE_SUPPORT
  7         bool
  8 
  9 config NOP_TRACER
 10         bool
 11 
 12 config HAVE_FTRACE_NMI_ENTER
 13         bool
 14         help
 15           See Documentation/trace/ftrace-design.txt
 16 
 17 config HAVE_FUNCTION_TRACER
 18         bool
 19         help
 20           See Documentation/trace/ftrace-design.txt
 21 
 22 config HAVE_FUNCTION_GRAPH_TRACER
 23         bool
 24         help
 25           See Documentation/trace/ftrace-design.txt
 26 
 27 config HAVE_FUNCTION_GRAPH_FP_TEST
 28         bool
 29         help
 30           See Documentation/trace/ftrace-design.txt
 31 
 32 config HAVE_DYNAMIC_FTRACE
 33         bool
 34         help
 35           See Documentation/trace/ftrace-design.txt
 36 
 37 config HAVE_DYNAMIC_FTRACE_WITH_REGS
 38         bool
 39 
 40 config HAVE_FTRACE_MCOUNT_RECORD
 41         bool
 42         help
 43           See Documentation/trace/ftrace-design.txt
 44 
 45 config HAVE_SYSCALL_TRACEPOINTS
 46         bool
 47         help
 48           See Documentation/trace/ftrace-design.txt
 49 
 50 config HAVE_FENTRY
 51         bool
 52         help
 53           Arch supports the gcc options -pg with -mfentry
 54 
 55 config HAVE_C_RECORDMCOUNT
 56         bool
 57         help
 58           C version of recordmcount available?
 59 
 60 config TRACER_MAX_TRACE
 61         bool
 62 
 63 config TRACE_CLOCK
 64         bool
 65 
 66 config RING_BUFFER
 67         bool
 68         select TRACE_CLOCK
 69         select IRQ_WORK
 70 
 71 config FTRACE_NMI_ENTER
 72        bool
 73        depends on HAVE_FTRACE_NMI_ENTER
 74        default y
 75 
 76 config EVENT_TRACING
 77         select CONTEXT_SWITCH_TRACER
 78         bool
 79 
 80 config CONTEXT_SWITCH_TRACER
 81         bool
 82 
 83 config RING_BUFFER_ALLOW_SWAP
 84         bool
 85         help
 86          Allow the use of ring_buffer_swap_cpu.
 87          Adds a very slight overhead to tracing when enabled.
 88 
 89 # All tracer options should select GENERIC_TRACER. For those options that are
 90 # enabled by all tracers (context switch and event tracer) they select TRACING.
 91 # This allows those options to appear when no other tracer is selected. But the
 92 # options do not appear when something else selects it. We need the two options
 93 # GENERIC_TRACER and TRACING to avoid circular dependencies to accomplish the
 94 # hiding of the automatic options.
 95 
 96 config TRACING
 97         bool
 98         select DEBUG_FS
 99         select RING_BUFFER
100         select STACKTRACE if STACKTRACE_SUPPORT
101         select TRACEPOINTS
102         select NOP_TRACER
103         select BINARY_PRINTF
104         select EVENT_TRACING
105         select TRACE_CLOCK
106 
107 config GENERIC_TRACER
108         bool
109         select TRACING
110 
111 #
112 # Minimum requirements an architecture has to meet for us to
113 # be able to offer generic tracing facilities:
114 #
115 config TRACING_SUPPORT
116         bool
117         # PPC32 has no irqflags tracing support, but it can use most of the
118         # tracers anyway, they were tested to build and work. Note that new
119         # exceptions to this list aren't welcomed, better implement the
120         # irqflags tracing for your architecture.
121         depends on TRACE_IRQFLAGS_SUPPORT || PPC32
122         depends on STACKTRACE_SUPPORT
123         default y
124 
125 if TRACING_SUPPORT
126 
127 menuconfig FTRACE
128         bool "Tracers"
129         default y if DEBUG_KERNEL
130         help
131           Enable the kernel tracing infrastructure.
132 
133 if FTRACE
134 
135 config FUNCTION_TRACER
136         bool "Kernel Function Tracer"
137         depends on HAVE_FUNCTION_TRACER
138         select KALLSYMS
139         select GENERIC_TRACER
140         select CONTEXT_SWITCH_TRACER
141         help
142           Enable the kernel to trace every kernel function. This is done
143           by using a compiler feature to insert a small, 5-byte No-Operation
144           instruction at the beginning of every kernel function, which NOP
145           sequence is then dynamically patched into a tracer call when
146           tracing is enabled by the administrator. If it's runtime disabled
147           (the bootup default), then the overhead of the instructions is very
148           small and not measurable even in micro-benchmarks.
149 
150 config FUNCTION_GRAPH_TRACER
151         bool "Kernel Function Graph Tracer"
152         depends on HAVE_FUNCTION_GRAPH_TRACER
153         depends on FUNCTION_TRACER
154         depends on !X86_32 || !CC_OPTIMIZE_FOR_SIZE
155         default y
156         help
157           Enable the kernel to trace a function at both its return
158           and its entry.
159           Its first purpose is to trace the duration of functions and
160           draw a call graph for each thread with some information like
161           the return value. This is done by setting the current return
162           address on the current task structure into a stack of calls.
163 
164 
165 config IRQSOFF_TRACER
166         bool "Interrupts-off Latency Tracer"
167         default n
168         depends on TRACE_IRQFLAGS_SUPPORT
169         depends on !ARCH_USES_GETTIMEOFFSET
170         select TRACE_IRQFLAGS
171         select GENERIC_TRACER
172         select TRACER_MAX_TRACE
173         select RING_BUFFER_ALLOW_SWAP
174         select TRACER_SNAPSHOT
175         select TRACER_SNAPSHOT_PER_CPU_SWAP
176         help
177           This option measures the time spent in irqs-off critical
178           sections, with microsecond accuracy.
179 
180           The default measurement method is a maximum search, which is
181           disabled by default and can be runtime (re-)started
182           via:
183 
184               echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
185 
186           (Note that kernel size and overhead increase with this option
187           enabled. This option and the preempt-off timing option can be
188           used together or separately.)
189 
190 config PREEMPT_TRACER
191         bool "Preemption-off Latency Tracer"
192         default n
193         depends on !ARCH_USES_GETTIMEOFFSET
194         depends on PREEMPT
195         select GENERIC_TRACER
196         select TRACER_MAX_TRACE
197         select RING_BUFFER_ALLOW_SWAP
198         select TRACER_SNAPSHOT
199         select TRACER_SNAPSHOT_PER_CPU_SWAP
200         help
201           This option measures the time spent in preemption-off critical
202           sections, with microsecond accuracy.
203 
204           The default measurement method is a maximum search, which is
205           disabled by default and can be runtime (re-)started
206           via:
207 
208               echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
209 
210           (Note that kernel size and overhead increase with this option
211           enabled. This option and the irqs-off timing option can be
212           used together or separately.)
213 
214 config SCHED_TRACER
215         bool "Scheduling Latency Tracer"
216         select GENERIC_TRACER
217         select CONTEXT_SWITCH_TRACER
218         select TRACER_MAX_TRACE
219         select TRACER_SNAPSHOT
220         help
221           This tracer tracks the latency of the highest priority task
222           to be scheduled in, starting from the point it has woken up.
223 
224 config ENABLE_DEFAULT_TRACERS
225         bool "Trace process context switches and events"
226         depends on !GENERIC_TRACER
227         select TRACING
228         help
229           This tracer hooks to various trace points in the kernel,
230           allowing the user to pick and choose which trace point they
231           want to trace. It also includes the sched_switch tracer plugin.
232 
233 config FTRACE_SYSCALLS
234         bool "Trace syscalls"
235         depends on HAVE_SYSCALL_TRACEPOINTS
236         select GENERIC_TRACER
237         select KALLSYMS
238         help
239           Basic tracer to catch the syscall entry and exit events.
240 
241 config TRACER_SNAPSHOT
242         bool "Create a snapshot trace buffer"
243         select TRACER_MAX_TRACE
244         help
245           Allow tracing users to take snapshot of the current buffer using the
246           ftrace interface, e.g.:
247 
248               echo 1 > /sys/kernel/debug/tracing/snapshot
249               cat snapshot
250 
251 config TRACER_SNAPSHOT_PER_CPU_SWAP
252         bool "Allow snapshot to swap per CPU"
253         depends on TRACER_SNAPSHOT
254         select RING_BUFFER_ALLOW_SWAP
255         help
256           Allow doing a snapshot of a single CPU buffer instead of a
257           full swap (all buffers). If this is set, then the following is
258           allowed:
259 
260               echo 1 > /sys/kernel/debug/tracing/per_cpu/cpu2/snapshot
261 
262           After which, only the tracing buffer for CPU 2 was swapped with
263           the main tracing buffer, and the other CPU buffers remain the same.
264 
265           When this is enabled, this adds a little more overhead to the
266           trace recording, as it needs to add some checks to synchronize
267           recording with swaps. But this does not affect the performance
268           of the overall system. This is enabled by default when the preempt
269           or irq latency tracers are enabled, as those need to swap as well
270           and already adds the overhead (plus a lot more).
271 
272 config TRACE_BRANCH_PROFILING
273         bool
274         select GENERIC_TRACER
275 
276 choice
277         prompt "Branch Profiling"
278         default BRANCH_PROFILE_NONE
279         help
280          The branch profiling is a software profiler. It will add hooks
281          into the C conditionals to test which path a branch takes.
282 
283          The likely/unlikely profiler only looks at the conditions that
284          are annotated with a likely or unlikely macro.
285 
286          The "all branch" profiler will profile every if-statement in the
287          kernel. This profiler will also enable the likely/unlikely
288          profiler.
289 
290          Either of the above profilers adds a bit of overhead to the system.
291          If unsure, choose "No branch profiling".
292 
293 config BRANCH_PROFILE_NONE
294         bool "No branch profiling"
295         help
296           No branch profiling. Branch profiling adds a bit of overhead.
297           Only enable it if you want to analyse the branching behavior.
298           Otherwise keep it disabled.
299 
300 config PROFILE_ANNOTATED_BRANCHES
301         bool "Trace likely/unlikely profiler"
302         select TRACE_BRANCH_PROFILING
303         help
304           This tracer profiles all likely and unlikely macros
305           in the kernel. It will display the results in:
306 
307           /sys/kernel/debug/tracing/trace_stat/branch_annotated
308 
309           Note: this will add a significant overhead; only turn this
310           on if you need to profile the system's use of these macros.
311 
312 config PROFILE_ALL_BRANCHES
313         bool "Profile all if conditionals"
314         select TRACE_BRANCH_PROFILING
315         help
316           This tracer profiles all branch conditions. Every if ()
317           taken in the kernel is recorded whether it hit or miss.
318           The results will be displayed in:
319 
320           /sys/kernel/debug/tracing/trace_stat/branch_all
321 
322           This option also enables the likely/unlikely profiler.
323 
324           This configuration, when enabled, will impose a great overhead
325           on the system. This should only be enabled when the system
326           is to be analyzed in much detail.
327 endchoice
328 
329 config TRACING_BRANCHES
330         bool
331         help
332           Selected by tracers that will trace the likely and unlikely
333           conditions. This prevents the tracers themselves from being
334           profiled. Profiling the tracing infrastructure can only happen
335           when the likelys and unlikelys are not being traced.
336 
337 config BRANCH_TRACER
338         bool "Trace likely/unlikely instances"
339         depends on TRACE_BRANCH_PROFILING
340         select TRACING_BRANCHES
341         help
342           This traces the events of likely and unlikely condition
343           calls in the kernel.  The difference between this and the
344           "Trace likely/unlikely profiler" is that this is not a
345           histogram of the callers, but actually places the calling
346           events into a running trace buffer to see when and where the
347           events happened, as well as their results.
348 
349           Say N if unsure.
350 
351 config STACK_TRACER
352         bool "Trace max stack"
353         depends on HAVE_FUNCTION_TRACER
354         select FUNCTION_TRACER
355         select STACKTRACE
356         select KALLSYMS
357         help
358           This special tracer records the maximum stack footprint of the
359           kernel and displays it in /sys/kernel/debug/tracing/stack_trace.
360 
361           This tracer works by hooking into every function call that the
362           kernel executes, and keeping a maximum stack depth value and
363           stack-trace saved.  If this is configured with DYNAMIC_FTRACE
364           then it will not have any overhead while the stack tracer
365           is disabled.
366 
367           To enable the stack tracer on bootup, pass in 'stacktrace'
368           on the kernel command line.
369 
370           The stack tracer can also be enabled or disabled via the
371           sysctl kernel.stack_tracer_enabled
372 
373           Say N if unsure.
374 
375 config BLK_DEV_IO_TRACE
376         bool "Support for tracing block IO actions"
377         depends on SYSFS
378         depends on BLOCK
379         select RELAY
380         select DEBUG_FS
381         select TRACEPOINTS
382         select GENERIC_TRACER
383         select STACKTRACE
384         help
385           Say Y here if you want to be able to trace the block layer actions
386           on a given queue. Tracing allows you to see any traffic happening
387           on a block device queue. For more information (and the userspace
388           support tools needed), fetch the blktrace tools from:
389 
390           git://git.kernel.dk/blktrace.git
391 
392           Tracing also is possible using the ftrace interface, e.g.:
393 
394             echo 1 > /sys/block/sda/sda1/trace/enable
395             echo blk > /sys/kernel/debug/tracing/current_tracer
396             cat /sys/kernel/debug/tracing/trace_pipe
397 
398           If unsure, say N.
399 
400 config KPROBE_EVENT
401         depends on KPROBES
402         depends on HAVE_REGS_AND_STACK_ACCESS_API
403         bool "Enable kprobes-based dynamic events"
404         select TRACING
405         select PROBE_EVENTS
406         default y
407         help
408           This allows the user to add tracing events (similar to tracepoints)
409           on the fly via the ftrace interface. See
410           Documentation/trace/kprobetrace.txt for more details.
411 
412           Those events can be inserted wherever kprobes can probe, and record
413           various register and memory values.
414 
415           This option is also required by perf-probe subcommand of perf tools.
416           If you want to use perf tools, this option is strongly recommended.
417 
418 config UPROBE_EVENT
419         bool "Enable uprobes-based dynamic events"
420         depends on ARCH_SUPPORTS_UPROBES
421         depends on MMU
422         depends on PERF_EVENTS
423         select UPROBES
424         select PROBE_EVENTS
425         select TRACING
426         default n
427         help
428           This allows the user to add tracing events on top of userspace
429           dynamic events (similar to tracepoints) on the fly via the trace
430           events interface. Those events can be inserted wherever uprobes
431           can probe, and record various registers.
432           This option is required if you plan to use perf-probe subcommand
433           of perf tools on user space applications.
434 
435 config BPF_EVENTS
436         depends on BPF_SYSCALL
437         depends on KPROBE_EVENT
438         bool
439         default y
440         help
441           This allows the user to attach BPF programs to kprobe events.
442 
443 config PROBE_EVENTS
444         def_bool n
445 
446 config DYNAMIC_FTRACE
447         bool "enable/disable function tracing dynamically"
448         depends on FUNCTION_TRACER
449         depends on HAVE_DYNAMIC_FTRACE
450         default y
451         help
452           This option will modify all the calls to function tracing
453           dynamically (will patch them out of the binary image and
454           replace them with a No-Op instruction) on boot up. During
455           compile time, a table is made of all the locations that ftrace
456           can function trace, and this table is linked into the kernel
457           image. When this is enabled, functions can be individually
458           enabled, and the functions not enabled will not affect
459           performance of the system.
460 
461           See the files in /sys/kernel/debug/tracing:
462             available_filter_functions
463             set_ftrace_filter
464             set_ftrace_notrace
465 
466           This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but
467           otherwise has native performance as long as no tracing is active.
468 
469 config DYNAMIC_FTRACE_WITH_REGS
470         def_bool y
471         depends on DYNAMIC_FTRACE
472         depends on HAVE_DYNAMIC_FTRACE_WITH_REGS
473 
474 config FUNCTION_PROFILER
475         bool "Kernel function profiler"
476         depends on FUNCTION_TRACER
477         default n
478         help
479           This option enables the kernel function profiler. A file is created
480           in debugfs called function_profile_enabled which defaults to zero.
481           When a 1 is echoed into this file profiling begins, and when a
482           zero is entered, profiling stops. A "functions" file is created in
483           the trace_stats directory; this file shows the list of functions that
484           have been hit and their counters.
485 
486           If in doubt, say N.
487 
488 config FTRACE_MCOUNT_RECORD
489         def_bool y
490         depends on DYNAMIC_FTRACE
491         depends on HAVE_FTRACE_MCOUNT_RECORD
492 
493 config FTRACE_SELFTEST
494         bool
495 
496 config FTRACE_STARTUP_TEST
497         bool "Perform a startup test on ftrace"
498         depends on GENERIC_TRACER
499         select FTRACE_SELFTEST
500         help
501           This option performs a series of startup tests on ftrace. On bootup
502           a series of tests are made to verify that the tracer is
503           functioning properly. It will do tests on all the configured
504           tracers of ftrace.
505 
506 config EVENT_TRACE_TEST_SYSCALLS
507         bool "Run selftest on syscall events"
508         depends on FTRACE_STARTUP_TEST
509         help
510          This option will also enable testing every syscall event.
511          It only enables the event and disables it and runs various loads
512          with the event enabled. This adds a bit more time for kernel boot
513          up since it runs this on every system call defined.
514 
515          TBD - enable a way to actually call the syscalls as we test their
516                events
517 
518 config MMIOTRACE
519         bool "Memory mapped IO tracing"
520         depends on HAVE_MMIOTRACE_SUPPORT && PCI
521         select GENERIC_TRACER
522         help
523           Mmiotrace traces Memory Mapped I/O access and is meant for
524           debugging and reverse engineering. It is called from the ioremap
525           implementation and works via page faults. Tracing is disabled by
526           default and can be enabled at run-time.
527 
528           See Documentation/trace/mmiotrace.txt.
529           If you are not helping to develop drivers, say N.
530 
531 config MMIOTRACE_TEST
532         tristate "Test module for mmiotrace"
533         depends on MMIOTRACE && m
534         help
535           This is a dumb module for testing mmiotrace. It is very dangerous
536           as it will write garbage to IO memory starting at a given address.
537           However, it should be safe to use on e.g. unused portion of VRAM.
538 
539           Say N, unless you absolutely know what you are doing.
540 
541 config TRACEPOINT_BENCHMARK
542         bool "Add tracepoint that benchmarks tracepoints"
543         help
544          This option creates the tracepoint "benchmark:benchmark_event".
545          When the tracepoint is enabled, it kicks off a kernel thread that
546          goes into an infinite loop (calling cond_sched() to let other tasks
547          run), and calls the tracepoint. Each iteration will record the time
548          it took to write to the tracepoint and the next iteration that
549          data will be passed to the tracepoint itself. That is, the tracepoint
550          will report the time it took to do the previous tracepoint.
551          The string written to the tracepoint is a static string of 128 bytes
552          to keep the time the same. The initial string is simply a write of
553          "START". The second string records the cold cache time of the first
554          write which is not added to the rest of the calculations.
555 
556          As it is a tight loop, it benchmarks as hot cache. That's fine because
557          we care most about hot paths that are probably in cache already.
558 
559          An example of the output:
560 
561               START
562               first=3672 [COLD CACHED]
563               last=632 first=3672 max=632 min=632 avg=316 std=446 std^2=199712
564               last=278 first=3672 max=632 min=278 avg=303 std=316 std^2=100337
565               last=277 first=3672 max=632 min=277 avg=296 std=258 std^2=67064
566               last=273 first=3672 max=632 min=273 avg=292 std=224 std^2=50411
567               last=273 first=3672 max=632 min=273 avg=288 std=200 std^2=40389
568               last=281 first=3672 max=632 min=273 avg=287 std=183 std^2=33666
569 
570 
571 config RING_BUFFER_BENCHMARK
572         tristate "Ring buffer benchmark stress tester"
573         depends on RING_BUFFER
574         help
575           This option creates a test to stress the ring buffer and benchmark it.
576           It creates its own ring buffer such that it will not interfere with
577           any other users of the ring buffer (such as ftrace). It then creates
578           a producer and consumer that will run for 10 seconds and sleep for
579           10 seconds. Each interval it will print out the number of events
580           it recorded and give a rough estimate of how long each iteration took.
581 
582           It does not disable interrupts or raise its priority, so it may be
583           affected by processes that are running.
584 
585           If unsure, say N.
586 
587 config RING_BUFFER_STARTUP_TEST
588        bool "Ring buffer startup self test"
589        depends on RING_BUFFER
590        help
591          Run a simple self test on the ring buffer on boot up. Late in the
592          kernel boot sequence, the test will start that kicks off
593          a thread per cpu. Each thread will write various size events
594          into the ring buffer. Another thread is created to send IPIs
595          to each of the threads, where the IPI handler will also write
596          to the ring buffer, to test/stress the nesting ability.
597          If any anomalies are discovered, a warning will be displayed
598          and all ring buffers will be disabled.
599 
600          The test runs for 10 seconds. This will slow your boot time
601          by at least 10 more seconds.
602 
603          At the end of the test, statics and more checks are done.
604          It will output the stats of each per cpu buffer. What
605          was written, the sizes, what was read, what was lost, and
606          other similar details.
607 
608          If unsure, say N
609 
610 config TRACE_ENUM_MAP_FILE
611        bool "Show enum mappings for trace events"
612        depends on TRACING
613        help
614         The "print fmt" of the trace events will show the enum names instead
615         of their values. This can cause problems for user space tools that
616         use this string to parse the raw data as user space does not know
617         how to convert the string to its value.
618 
619         To fix this, there's a special macro in the kernel that can be used
620         to convert the enum into its value. If this macro is used, then the
621         print fmt strings will have the enums converted to their values.
622 
623         If something does not get converted properly, this option can be
624         used to show what enums the kernel tried to convert.
625 
626         This option is for debugging the enum conversions. A file is created
627         in the tracing directory called "enum_map" that will show the enum
628         names matched with their values and what trace event system they
629         belong too.
630 
631         Normally, the mapping of the strings to values will be freed after
632         boot up or module load. With this option, they will not be freed, as
633         they are needed for the "enum_map" file. Enabling this option will
634         increase the memory footprint of the running kernel.
635 
636         If unsure, say N
637 
638 endif # FTRACE
639 
640 endif # TRACING_SUPPORT
641 

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