1 # SPDX-License-Identifier: GPL-2.0-only <<
2 # 1 #
3 # Architectures that offer an FUNCTION_TRACER 2 # Architectures that offer an FUNCTION_TRACER implementation should
4 # select HAVE_FUNCTION_TRACER: 3 # select HAVE_FUNCTION_TRACER:
5 # 4 #
6 5
7 config USER_STACKTRACE_SUPPORT 6 config USER_STACKTRACE_SUPPORT
8 bool 7 bool
9 8
10 config NOP_TRACER 9 config NOP_TRACER
11 bool 10 bool
12 11
13 config HAVE_RETHOOK !! 12 config HAVE_FTRACE_NMI_ENTER
14 bool 13 bool
15 <<
16 config RETHOOK <<
17 bool <<
18 depends on HAVE_RETHOOK <<
19 help 14 help
20 Enable generic return hooking featur !! 15 See Documentation/trace/ftrace-design.rst
21 API, which will be used by other fun <<
22 features like fprobe and kprobes. <<
23 16
24 config HAVE_FUNCTION_TRACER 17 config HAVE_FUNCTION_TRACER
25 bool 18 bool
26 help 19 help
27 See Documentation/trace/ftrace-desig 20 See Documentation/trace/ftrace-design.rst
28 21
29 config HAVE_FUNCTION_GRAPH_TRACER 22 config HAVE_FUNCTION_GRAPH_TRACER
30 bool 23 bool
31 help 24 help
32 See Documentation/trace/ftrace-desig 25 See Documentation/trace/ftrace-design.rst
33 26
34 config HAVE_FUNCTION_GRAPH_RETVAL <<
35 bool <<
36 <<
37 config HAVE_DYNAMIC_FTRACE 27 config HAVE_DYNAMIC_FTRACE
38 bool 28 bool
39 help 29 help
40 See Documentation/trace/ftrace-desig 30 See Documentation/trace/ftrace-design.rst
41 31
42 config HAVE_DYNAMIC_FTRACE_WITH_REGS 32 config HAVE_DYNAMIC_FTRACE_WITH_REGS
43 bool 33 bool
44 34
45 config HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS <<
46 bool <<
47 <<
48 config HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS <<
49 bool <<
50 <<
51 config HAVE_DYNAMIC_FTRACE_WITH_ARGS <<
52 bool <<
53 help <<
54 If this is set, then arguments and st <<
55 the ftrace_regs passed into the funct <<
56 by default, even without setting the <<
57 This allows for use of ftrace_regs_ge <<
58 ftrace_regs_get_stack_pointer(). <<
59 <<
60 config HAVE_DYNAMIC_FTRACE_NO_PATCHABLE <<
61 bool <<
62 help <<
63 If the architecture generates __patc <<
64 but does not want them included in t <<
65 <<
66 config HAVE_FTRACE_MCOUNT_RECORD 35 config HAVE_FTRACE_MCOUNT_RECORD
67 bool 36 bool
68 help 37 help
69 See Documentation/trace/ftrace-desig 38 See Documentation/trace/ftrace-design.rst
70 39
71 config HAVE_SYSCALL_TRACEPOINTS 40 config HAVE_SYSCALL_TRACEPOINTS
72 bool 41 bool
73 help 42 help
74 See Documentation/trace/ftrace-desig 43 See Documentation/trace/ftrace-design.rst
75 44
76 config HAVE_FENTRY 45 config HAVE_FENTRY
77 bool 46 bool
78 help 47 help
79 Arch supports the gcc options -pg wi 48 Arch supports the gcc options -pg with -mfentry
80 49
81 config HAVE_NOP_MCOUNT 50 config HAVE_NOP_MCOUNT
82 bool 51 bool
83 help 52 help
84 Arch supports the gcc options -pg wi 53 Arch supports the gcc options -pg with -mrecord-mcount and -nop-mcount
85 54
86 config HAVE_OBJTOOL_MCOUNT <<
87 bool <<
88 help <<
89 Arch supports objtool --mcount <<
90 <<
91 config HAVE_OBJTOOL_NOP_MCOUNT <<
92 bool <<
93 help <<
94 Arch supports the objtool options -- <<
95 An architecture can select this if i <<
96 of ftrace locations. <<
97 <<
98 config HAVE_C_RECORDMCOUNT 55 config HAVE_C_RECORDMCOUNT
99 bool 56 bool
100 help 57 help
101 C version of recordmcount available? 58 C version of recordmcount available?
102 59
103 config HAVE_BUILDTIME_MCOUNT_SORT <<
104 bool <<
105 help <<
106 An architecture selects this if it so <<
107 at build time. <<
108 <<
109 config BUILDTIME_MCOUNT_SORT <<
110 bool <<
111 default y <<
112 depends on HAVE_BUILDTIME_MCOUNT_SORT & <<
113 help <<
114 Sort the mcount_loc section at build <<
115 <<
116 config TRACER_MAX_TRACE 60 config TRACER_MAX_TRACE
117 bool 61 bool
118 62
119 config TRACE_CLOCK 63 config TRACE_CLOCK
120 bool 64 bool
121 65
122 config RING_BUFFER 66 config RING_BUFFER
123 bool 67 bool
124 select TRACE_CLOCK 68 select TRACE_CLOCK
125 select IRQ_WORK 69 select IRQ_WORK
126 70
>> 71 config FTRACE_NMI_ENTER
>> 72 bool
>> 73 depends on HAVE_FTRACE_NMI_ENTER
>> 74 default y
>> 75
127 config EVENT_TRACING 76 config EVENT_TRACING
128 select CONTEXT_SWITCH_TRACER 77 select CONTEXT_SWITCH_TRACER
129 select GLOB !! 78 select GLOB
130 bool 79 bool
131 80
132 config CONTEXT_SWITCH_TRACER 81 config CONTEXT_SWITCH_TRACER
133 bool 82 bool
134 83
135 config RING_BUFFER_ALLOW_SWAP 84 config RING_BUFFER_ALLOW_SWAP
136 bool 85 bool
137 help 86 help
138 Allow the use of ring_buffer_swap_cpu 87 Allow the use of ring_buffer_swap_cpu.
139 Adds a very slight overhead to tracin 88 Adds a very slight overhead to tracing when enabled.
140 89
141 config PREEMPTIRQ_TRACEPOINTS 90 config PREEMPTIRQ_TRACEPOINTS
142 bool 91 bool
143 depends on TRACE_PREEMPT_TOGGLE || TRA 92 depends on TRACE_PREEMPT_TOGGLE || TRACE_IRQFLAGS
144 select TRACING 93 select TRACING
145 default y 94 default y
146 help 95 help
147 Create preempt/irq toggle tracepoint 96 Create preempt/irq toggle tracepoints if needed, so that other parts
148 of the kernel can use them to genera 97 of the kernel can use them to generate or add hooks to them.
149 98
150 # All tracer options should select GENERIC_TRA 99 # All tracer options should select GENERIC_TRACER. For those options that are
151 # enabled by all tracers (context switch and e 100 # enabled by all tracers (context switch and event tracer) they select TRACING.
152 # This allows those options to appear when no 101 # This allows those options to appear when no other tracer is selected. But the
153 # options do not appear when something else se 102 # options do not appear when something else selects it. We need the two options
154 # GENERIC_TRACER and TRACING to avoid circular 103 # GENERIC_TRACER and TRACING to avoid circular dependencies to accomplish the
155 # hiding of the automatic options. 104 # hiding of the automatic options.
156 105
157 config TRACING 106 config TRACING
158 bool 107 bool
>> 108 select DEBUG_FS
159 select RING_BUFFER 109 select RING_BUFFER
160 select STACKTRACE if STACKTRACE_SUPPOR 110 select STACKTRACE if STACKTRACE_SUPPORT
161 select TRACEPOINTS 111 select TRACEPOINTS
162 select NOP_TRACER 112 select NOP_TRACER
163 select BINARY_PRINTF 113 select BINARY_PRINTF
164 select EVENT_TRACING 114 select EVENT_TRACING
165 select TRACE_CLOCK 115 select TRACE_CLOCK
166 select NEED_TASKS_RCU <<
167 116
168 config GENERIC_TRACER 117 config GENERIC_TRACER
169 bool 118 bool
170 select TRACING 119 select TRACING
171 120
172 # 121 #
173 # Minimum requirements an architecture has to 122 # Minimum requirements an architecture has to meet for us to
174 # be able to offer generic tracing facilities: 123 # be able to offer generic tracing facilities:
175 # 124 #
176 config TRACING_SUPPORT 125 config TRACING_SUPPORT
177 bool 126 bool
178 depends on TRACE_IRQFLAGS_SUPPORT 127 depends on TRACE_IRQFLAGS_SUPPORT
179 depends on STACKTRACE_SUPPORT 128 depends on STACKTRACE_SUPPORT
180 default y 129 default y
181 130
>> 131 if TRACING_SUPPORT
>> 132
182 menuconfig FTRACE 133 menuconfig FTRACE
183 bool "Tracers" 134 bool "Tracers"
184 depends on TRACING_SUPPORT <<
185 default y if DEBUG_KERNEL 135 default y if DEBUG_KERNEL
186 help 136 help
187 Enable the kernel tracing infrastruc 137 Enable the kernel tracing infrastructure.
188 138
189 if FTRACE 139 if FTRACE
190 140
191 config BOOTTIME_TRACING <<
192 bool "Boot-time Tracing support" <<
193 depends on TRACING <<
194 select BOOT_CONFIG <<
195 help <<
196 Enable developer to setup ftrace sub <<
197 kernel cmdline at boot time for debu <<
198 initialization and boot process. <<
199 <<
200 config FUNCTION_TRACER 141 config FUNCTION_TRACER
201 bool "Kernel Function Tracer" 142 bool "Kernel Function Tracer"
202 depends on HAVE_FUNCTION_TRACER 143 depends on HAVE_FUNCTION_TRACER
203 select KALLSYMS 144 select KALLSYMS
204 select GENERIC_TRACER 145 select GENERIC_TRACER
205 select CONTEXT_SWITCH_TRACER 146 select CONTEXT_SWITCH_TRACER
206 select GLOB 147 select GLOB
207 select NEED_TASKS_RCU !! 148 select TASKS_RCU if PREEMPT
208 select TASKS_RUDE_RCU <<
209 help 149 help
210 Enable the kernel to trace every ker 150 Enable the kernel to trace every kernel function. This is done
211 by using a compiler feature to inser 151 by using a compiler feature to insert a small, 5-byte No-Operation
212 instruction at the beginning of ever 152 instruction at the beginning of every kernel function, which NOP
213 sequence is then dynamically patched 153 sequence is then dynamically patched into a tracer call when
214 tracing is enabled by the administra 154 tracing is enabled by the administrator. If it's runtime disabled
215 (the bootup default), then the overh 155 (the bootup default), then the overhead of the instructions is very
216 small and not measurable even in mic !! 156 small and not measurable even in micro-benchmarks.
217 x86, but may have impact on other ar <<
218 157
219 config FUNCTION_GRAPH_TRACER 158 config FUNCTION_GRAPH_TRACER
220 bool "Kernel Function Graph Tracer" 159 bool "Kernel Function Graph Tracer"
221 depends on HAVE_FUNCTION_GRAPH_TRACER 160 depends on HAVE_FUNCTION_GRAPH_TRACER
222 depends on FUNCTION_TRACER 161 depends on FUNCTION_TRACER
223 depends on !X86_32 || !CC_OPTIMIZE_FOR 162 depends on !X86_32 || !CC_OPTIMIZE_FOR_SIZE
224 default y 163 default y
225 help 164 help
226 Enable the kernel to trace a functio 165 Enable the kernel to trace a function at both its return
227 and its entry. 166 and its entry.
228 Its first purpose is to trace the du 167 Its first purpose is to trace the duration of functions and
229 draw a call graph for each thread wi 168 draw a call graph for each thread with some information like
230 the return value. This is done by se 169 the return value. This is done by setting the current return
231 address on the current task structur 170 address on the current task structure into a stack of calls.
232 171
233 config FUNCTION_GRAPH_RETVAL <<
234 bool "Kernel Function Graph Return Val <<
235 depends on HAVE_FUNCTION_GRAPH_RETVAL <<
236 depends on FUNCTION_GRAPH_TRACER <<
237 default n <<
238 help <<
239 Support recording and printing the f <<
240 using function graph tracer. It can <<
241 that return errors. This feature is <<
242 enable it via the trace option funcg <<
243 See Documentation/trace/ftrace.rst <<
244 <<
245 config DYNAMIC_FTRACE <<
246 bool "enable/disable function tracing <<
247 depends on FUNCTION_TRACER <<
248 depends on HAVE_DYNAMIC_FTRACE <<
249 default y <<
250 help <<
251 This option will modify all the call <<
252 dynamically (will patch them out of <<
253 replace them with a No-Op instructio <<
254 compile time, a table is made of all <<
255 can function trace, and this table i <<
256 image. When this is enabled, functio <<
257 enabled, and the functions not enabl <<
258 performance of the system. <<
259 <<
260 See the files in /sys/kernel/tracing <<
261 available_filter_functions <<
262 set_ftrace_filter <<
263 set_ftrace_notrace <<
264 <<
265 This way a CONFIG_FUNCTION_TRACER ke <<
266 otherwise has native performance as <<
267 <<
268 config DYNAMIC_FTRACE_WITH_REGS <<
269 def_bool y <<
270 depends on DYNAMIC_FTRACE <<
271 depends on HAVE_DYNAMIC_FTRACE_WITH_RE <<
272 <<
273 config DYNAMIC_FTRACE_WITH_DIRECT_CALLS <<
274 def_bool y <<
275 depends on DYNAMIC_FTRACE_WITH_REGS || <<
276 depends on HAVE_DYNAMIC_FTRACE_WITH_DI <<
277 <<
278 config DYNAMIC_FTRACE_WITH_CALL_OPS <<
279 def_bool y <<
280 depends on HAVE_DYNAMIC_FTRACE_WITH_CA <<
281 <<
282 config DYNAMIC_FTRACE_WITH_ARGS <<
283 def_bool y <<
284 depends on DYNAMIC_FTRACE <<
285 depends on HAVE_DYNAMIC_FTRACE_WITH_AR <<
286 <<
287 config FPROBE <<
288 bool "Kernel Function Probe (fprobe)" <<
289 depends on FUNCTION_TRACER <<
290 depends on DYNAMIC_FTRACE_WITH_REGS <<
291 depends on HAVE_RETHOOK <<
292 select RETHOOK <<
293 default n <<
294 help <<
295 This option enables kernel function <<
296 The fprobe is similar to kprobes, bu <<
297 entries and exits. This also can pro <<
298 fprobe. <<
299 <<
300 If unsure, say N. <<
301 <<
302 config FUNCTION_PROFILER <<
303 bool "Kernel function profiler" <<
304 depends on FUNCTION_TRACER <<
305 default n <<
306 help <<
307 This option enables the kernel funct <<
308 in debugfs called function_profile_e <<
309 When a 1 is echoed into this file pr <<
310 zero is entered, profiling stops. A <<
311 the trace_stat directory; this file <<
312 have been hit and their counters. <<
313 <<
314 If in doubt, say N. <<
315 <<
316 config STACK_TRACER <<
317 bool "Trace max stack" <<
318 depends on HAVE_FUNCTION_TRACER <<
319 select FUNCTION_TRACER <<
320 select STACKTRACE <<
321 select KALLSYMS <<
322 help <<
323 This special tracer records the maxi <<
324 kernel and displays it in /sys/kerne <<
325 <<
326 This tracer works by hooking into ev <<
327 kernel executes, and keeping a maxim <<
328 stack-trace saved. If this is confi <<
329 then it will not have any overhead w <<
330 is disabled. <<
331 <<
332 To enable the stack tracer on bootup <<
333 on the kernel command line. <<
334 <<
335 The stack tracer can also be enabled <<
336 sysctl kernel.stack_tracer_enabled <<
337 <<
338 Say N if unsure. <<
339 <<
340 config TRACE_PREEMPT_TOGGLE 172 config TRACE_PREEMPT_TOGGLE
341 bool 173 bool
342 help 174 help
343 Enables hooks which will be called w 175 Enables hooks which will be called when preemption is first disabled,
344 and last enabled. 176 and last enabled.
345 177
>> 178 config PREEMPTIRQ_EVENTS
>> 179 bool "Enable trace events for preempt and irq disable/enable"
>> 180 select TRACE_IRQFLAGS
>> 181 select TRACE_PREEMPT_TOGGLE if PREEMPT
>> 182 select GENERIC_TRACER
>> 183 default n
>> 184 help
>> 185 Enable tracing of disable and enable events for preemption and irqs.
>> 186
346 config IRQSOFF_TRACER 187 config IRQSOFF_TRACER
347 bool "Interrupts-off Latency Tracer" 188 bool "Interrupts-off Latency Tracer"
348 default n 189 default n
349 depends on TRACE_IRQFLAGS_SUPPORT 190 depends on TRACE_IRQFLAGS_SUPPORT
>> 191 depends on !ARCH_USES_GETTIMEOFFSET
350 select TRACE_IRQFLAGS 192 select TRACE_IRQFLAGS
351 select GENERIC_TRACER 193 select GENERIC_TRACER
352 select TRACER_MAX_TRACE 194 select TRACER_MAX_TRACE
353 select RING_BUFFER_ALLOW_SWAP 195 select RING_BUFFER_ALLOW_SWAP
354 select TRACER_SNAPSHOT 196 select TRACER_SNAPSHOT
355 select TRACER_SNAPSHOT_PER_CPU_SWAP 197 select TRACER_SNAPSHOT_PER_CPU_SWAP
356 help 198 help
357 This option measures the time spent 199 This option measures the time spent in irqs-off critical
358 sections, with microsecond accuracy. 200 sections, with microsecond accuracy.
359 201
360 The default measurement method is a 202 The default measurement method is a maximum search, which is
361 disabled by default and can be runti 203 disabled by default and can be runtime (re-)started
362 via: 204 via:
363 205
364 echo 0 > /sys/kernel/tracing/tra !! 206 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
365 207
366 (Note that kernel size and overhead 208 (Note that kernel size and overhead increase with this option
367 enabled. This option and the preempt 209 enabled. This option and the preempt-off timing option can be
368 used together or separately.) 210 used together or separately.)
369 211
370 config PREEMPT_TRACER 212 config PREEMPT_TRACER
371 bool "Preemption-off Latency Tracer" 213 bool "Preemption-off Latency Tracer"
372 default n 214 default n
373 depends on PREEMPTION !! 215 depends on !ARCH_USES_GETTIMEOFFSET
>> 216 depends on PREEMPT
374 select GENERIC_TRACER 217 select GENERIC_TRACER
375 select TRACER_MAX_TRACE 218 select TRACER_MAX_TRACE
376 select RING_BUFFER_ALLOW_SWAP 219 select RING_BUFFER_ALLOW_SWAP
377 select TRACER_SNAPSHOT 220 select TRACER_SNAPSHOT
378 select TRACER_SNAPSHOT_PER_CPU_SWAP 221 select TRACER_SNAPSHOT_PER_CPU_SWAP
379 select TRACE_PREEMPT_TOGGLE 222 select TRACE_PREEMPT_TOGGLE
380 help 223 help
381 This option measures the time spent 224 This option measures the time spent in preemption-off critical
382 sections, with microsecond accuracy. 225 sections, with microsecond accuracy.
383 226
384 The default measurement method is a 227 The default measurement method is a maximum search, which is
385 disabled by default and can be runti 228 disabled by default and can be runtime (re-)started
386 via: 229 via:
387 230
388 echo 0 > /sys/kernel/tracing/tra !! 231 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
389 232
390 (Note that kernel size and overhead 233 (Note that kernel size and overhead increase with this option
391 enabled. This option and the irqs-of 234 enabled. This option and the irqs-off timing option can be
392 used together or separately.) 235 used together or separately.)
393 236
394 config SCHED_TRACER 237 config SCHED_TRACER
395 bool "Scheduling Latency Tracer" 238 bool "Scheduling Latency Tracer"
396 select GENERIC_TRACER 239 select GENERIC_TRACER
397 select CONTEXT_SWITCH_TRACER 240 select CONTEXT_SWITCH_TRACER
398 select TRACER_MAX_TRACE 241 select TRACER_MAX_TRACE
399 select TRACER_SNAPSHOT 242 select TRACER_SNAPSHOT
400 help 243 help
401 This tracer tracks the latency of th 244 This tracer tracks the latency of the highest priority task
402 to be scheduled in, starting from th 245 to be scheduled in, starting from the point it has woken up.
403 246
404 config HWLAT_TRACER 247 config HWLAT_TRACER
405 bool "Tracer to detect hardware latenc 248 bool "Tracer to detect hardware latencies (like SMIs)"
406 select GENERIC_TRACER 249 select GENERIC_TRACER
407 select TRACER_MAX_TRACE <<
408 help 250 help
409 This tracer, when enabled will create 251 This tracer, when enabled will create one or more kernel threads,
410 depending on what the cpumask file is 252 depending on what the cpumask file is set to, which each thread
411 spinning in a loop looking for interr 253 spinning in a loop looking for interruptions caused by
412 something other than the kernel. For 254 something other than the kernel. For example, if a
413 System Management Interrupt (SMI) tak 255 System Management Interrupt (SMI) takes a noticeable amount of
414 time, this tracer will detect it. Thi 256 time, this tracer will detect it. This is useful for testing
415 if a system is reliable for Real Time 257 if a system is reliable for Real Time tasks.
416 258
417 Some files are created in the tracing 259 Some files are created in the tracing directory when this
418 is enabled: 260 is enabled:
419 261
420 hwlat_detector/width - time in us 262 hwlat_detector/width - time in usecs for how long to spin for
421 hwlat_detector/window - time in us 263 hwlat_detector/window - time in usecs between the start of each
422 iteration 264 iteration
423 265
424 A kernel thread is created that will 266 A kernel thread is created that will spin with interrupts disabled
425 for "width" microseconds in every "wi 267 for "width" microseconds in every "window" cycle. It will not spin
426 for "window - width" microseconds, wh 268 for "window - width" microseconds, where the system can
427 continue to operate. 269 continue to operate.
428 270
429 The output will appear in the trace a 271 The output will appear in the trace and trace_pipe files.
430 272
431 When the tracer is not running, it ha 273 When the tracer is not running, it has no affect on the system,
432 but when it is running, it can cause 274 but when it is running, it can cause the system to be
433 periodically non responsive. Do not r 275 periodically non responsive. Do not run this tracer on a
434 production system. 276 production system.
435 277
436 To enable this tracer, echo in "hwlat 278 To enable this tracer, echo in "hwlat" into the current_tracer
437 file. Every time a latency is greater 279 file. Every time a latency is greater than tracing_thresh, it will
438 be recorded into the ring buffer. 280 be recorded into the ring buffer.
439 281
440 config OSNOISE_TRACER <<
441 bool "OS Noise tracer" <<
442 select GENERIC_TRACER <<
443 select TRACER_MAX_TRACE <<
444 help <<
445 In the context of high-performance c <<
446 System Noise (osnoise) refers to the <<
447 application due to activities inside <<
448 context of Linux, NMIs, IRQs, SoftIR <<
449 can cause noise to the system. Moreo <<
450 also cause noise, for example, via S <<
451 <<
452 The osnoise tracer leverages the hwl <<
453 loop with preemption, SoftIRQs and I <<
454 the sources of osnoise during its ex <<
455 note of the entry and exit point of <<
456 increasing a per-cpu interference co <<
457 counter for each source of interfere <<
458 NMI, IRQs, SoftIRQs, and threads is <<
459 observes these interferences' entry <<
460 without any interference from the op <<
461 hardware noise counter increases, po <<
462 noise. In this way, osnoise can acco <<
463 interference. At the end of the peri <<
464 the sum of all noise, the max single <<
465 available for the thread, and the co <<
466 <<
467 In addition to the tracer, a set of <<
468 facilitate the identification of the <<
469 <<
470 The output will appear in the trace <<
471 <<
472 To enable this tracer, echo in "osno <<
473 file. <<
474 <<
475 config TIMERLAT_TRACER <<
476 bool "Timerlat tracer" <<
477 select OSNOISE_TRACER <<
478 select GENERIC_TRACER <<
479 help <<
480 The timerlat tracer aims to help the <<
481 to find sources of wakeup latencies <<
482 <<
483 The tracer creates a per-cpu kernel <<
484 The tracer thread sets a periodic ti <<
485 to sleep waiting for the timer to fi <<
486 then computes a wakeup latency value <<
487 the current time and the absolute ti <<
488 to expire. <<
489 <<
490 The tracer prints two lines at every <<
491 timer latency observed at the hardir <<
492 activation of the thread. The second <<
493 by the thread, which is the same lev <<
494 ACTIVATION ID field serves to relate <<
495 respective thread execution. <<
496 <<
497 The tracer is build on top of osnois <<
498 events can be used to trace the sour <<
499 IRQs and other threads. It also enab <<
500 stacktrace at the IRQ context, which <<
501 path that can cause thread delay. <<
502 <<
503 config MMIOTRACE <<
504 bool "Memory mapped IO tracing" <<
505 depends on HAVE_MMIOTRACE_SUPPORT && P <<
506 select GENERIC_TRACER <<
507 help <<
508 Mmiotrace traces Memory Mapped I/O a <<
509 debugging and reverse engineering. I <<
510 implementation and works via page fa <<
511 default and can be enabled at run-ti <<
512 <<
513 See Documentation/trace/mmiotrace.rs <<
514 If you are not helping to develop dr <<
515 <<
516 config ENABLE_DEFAULT_TRACERS 282 config ENABLE_DEFAULT_TRACERS
517 bool "Trace process context switches a 283 bool "Trace process context switches and events"
518 depends on !GENERIC_TRACER 284 depends on !GENERIC_TRACER
519 select TRACING 285 select TRACING
520 help 286 help
521 This tracer hooks to various trace p 287 This tracer hooks to various trace points in the kernel,
522 allowing the user to pick and choose 288 allowing the user to pick and choose which trace point they
523 want to trace. It also includes the 289 want to trace. It also includes the sched_switch tracer plugin.
524 290
525 config FTRACE_SYSCALLS 291 config FTRACE_SYSCALLS
526 bool "Trace syscalls" 292 bool "Trace syscalls"
527 depends on HAVE_SYSCALL_TRACEPOINTS 293 depends on HAVE_SYSCALL_TRACEPOINTS
528 select GENERIC_TRACER 294 select GENERIC_TRACER
529 select KALLSYMS 295 select KALLSYMS
530 help 296 help
531 Basic tracer to catch the syscall en 297 Basic tracer to catch the syscall entry and exit events.
532 298
533 config TRACER_SNAPSHOT 299 config TRACER_SNAPSHOT
534 bool "Create a snapshot trace buffer" 300 bool "Create a snapshot trace buffer"
535 select TRACER_MAX_TRACE 301 select TRACER_MAX_TRACE
536 help 302 help
537 Allow tracing users to take snapshot 303 Allow tracing users to take snapshot of the current buffer using the
538 ftrace interface, e.g.: 304 ftrace interface, e.g.:
539 305
540 echo 1 > /sys/kernel/tracing/sna !! 306 echo 1 > /sys/kernel/debug/tracing/snapshot
541 cat snapshot 307 cat snapshot
542 308
543 config TRACER_SNAPSHOT_PER_CPU_SWAP 309 config TRACER_SNAPSHOT_PER_CPU_SWAP
544 bool "Allow snapshot to swap per CPU" !! 310 bool "Allow snapshot to swap per CPU"
545 depends on TRACER_SNAPSHOT 311 depends on TRACER_SNAPSHOT
546 select RING_BUFFER_ALLOW_SWAP 312 select RING_BUFFER_ALLOW_SWAP
547 help 313 help
548 Allow doing a snapshot of a single C 314 Allow doing a snapshot of a single CPU buffer instead of a
549 full swap (all buffers). If this is 315 full swap (all buffers). If this is set, then the following is
550 allowed: 316 allowed:
551 317
552 echo 1 > /sys/kernel/tracing/per !! 318 echo 1 > /sys/kernel/debug/tracing/per_cpu/cpu2/snapshot
553 319
554 After which, only the tracing buffer 320 After which, only the tracing buffer for CPU 2 was swapped with
555 the main tracing buffer, and the oth 321 the main tracing buffer, and the other CPU buffers remain the same.
556 322
557 When this is enabled, this adds a li 323 When this is enabled, this adds a little more overhead to the
558 trace recording, as it needs to add 324 trace recording, as it needs to add some checks to synchronize
559 recording with swaps. But this does 325 recording with swaps. But this does not affect the performance
560 of the overall system. This is enabl 326 of the overall system. This is enabled by default when the preempt
561 or irq latency tracers are enabled, 327 or irq latency tracers are enabled, as those need to swap as well
562 and already adds the overhead (plus 328 and already adds the overhead (plus a lot more).
563 329
564 config TRACE_BRANCH_PROFILING 330 config TRACE_BRANCH_PROFILING
565 bool 331 bool
566 select GENERIC_TRACER 332 select GENERIC_TRACER
567 333
568 choice 334 choice
569 prompt "Branch Profiling" 335 prompt "Branch Profiling"
570 default BRANCH_PROFILE_NONE 336 default BRANCH_PROFILE_NONE
571 help 337 help
572 The branch profiling is a software pr 338 The branch profiling is a software profiler. It will add hooks
573 into the C conditionals to test which 339 into the C conditionals to test which path a branch takes.
574 340
575 The likely/unlikely profiler only loo 341 The likely/unlikely profiler only looks at the conditions that
576 are annotated with a likely or unlike 342 are annotated with a likely or unlikely macro.
577 343
578 The "all branch" profiler will profil 344 The "all branch" profiler will profile every if-statement in the
579 kernel. This profiler will also enabl 345 kernel. This profiler will also enable the likely/unlikely
580 profiler. 346 profiler.
581 347
582 Either of the above profilers adds a 348 Either of the above profilers adds a bit of overhead to the system.
583 If unsure, choose "No branch profilin 349 If unsure, choose "No branch profiling".
584 350
585 config BRANCH_PROFILE_NONE 351 config BRANCH_PROFILE_NONE
586 bool "No branch profiling" 352 bool "No branch profiling"
587 help 353 help
588 No branch profiling. Branch profilin 354 No branch profiling. Branch profiling adds a bit of overhead.
589 Only enable it if you want to analys 355 Only enable it if you want to analyse the branching behavior.
590 Otherwise keep it disabled. 356 Otherwise keep it disabled.
591 357
592 config PROFILE_ANNOTATED_BRANCHES 358 config PROFILE_ANNOTATED_BRANCHES
593 bool "Trace likely/unlikely profiler" 359 bool "Trace likely/unlikely profiler"
594 select TRACE_BRANCH_PROFILING 360 select TRACE_BRANCH_PROFILING
595 help 361 help
596 This tracer profiles all likely and 362 This tracer profiles all likely and unlikely macros
597 in the kernel. It will display the r 363 in the kernel. It will display the results in:
598 364
599 /sys/kernel/tracing/trace_stat/branc !! 365 /sys/kernel/debug/tracing/trace_stat/branch_annotated
600 366
601 Note: this will add a significant ov 367 Note: this will add a significant overhead; only turn this
602 on if you need to profile the system 368 on if you need to profile the system's use of these macros.
603 369
604 config PROFILE_ALL_BRANCHES 370 config PROFILE_ALL_BRANCHES
605 bool "Profile all if conditionals" if 371 bool "Profile all if conditionals" if !FORTIFY_SOURCE
606 select TRACE_BRANCH_PROFILING 372 select TRACE_BRANCH_PROFILING
607 help 373 help
608 This tracer profiles all branch cond 374 This tracer profiles all branch conditions. Every if ()
609 taken in the kernel is recorded whet 375 taken in the kernel is recorded whether it hit or miss.
610 The results will be displayed in: 376 The results will be displayed in:
611 377
612 /sys/kernel/tracing/trace_stat/branc !! 378 /sys/kernel/debug/tracing/trace_stat/branch_all
613 379
614 This option also enables the likely/ 380 This option also enables the likely/unlikely profiler.
615 381
616 This configuration, when enabled, wi 382 This configuration, when enabled, will impose a great overhead
617 on the system. This should only be e 383 on the system. This should only be enabled when the system
618 is to be analyzed in much detail. 384 is to be analyzed in much detail.
619 endchoice 385 endchoice
620 386
621 config TRACING_BRANCHES 387 config TRACING_BRANCHES
622 bool 388 bool
623 help 389 help
624 Selected by tracers that will trace 390 Selected by tracers that will trace the likely and unlikely
625 conditions. This prevents the tracer 391 conditions. This prevents the tracers themselves from being
626 profiled. Profiling the tracing infr 392 profiled. Profiling the tracing infrastructure can only happen
627 when the likelys and unlikelys are n 393 when the likelys and unlikelys are not being traced.
628 394
629 config BRANCH_TRACER 395 config BRANCH_TRACER
630 bool "Trace likely/unlikely instances" 396 bool "Trace likely/unlikely instances"
631 depends on TRACE_BRANCH_PROFILING 397 depends on TRACE_BRANCH_PROFILING
632 select TRACING_BRANCHES 398 select TRACING_BRANCHES
633 help 399 help
634 This traces the events of likely and 400 This traces the events of likely and unlikely condition
635 calls in the kernel. The difference 401 calls in the kernel. The difference between this and the
636 "Trace likely/unlikely profiler" is 402 "Trace likely/unlikely profiler" is that this is not a
637 histogram of the callers, but actual 403 histogram of the callers, but actually places the calling
638 events into a running trace buffer t 404 events into a running trace buffer to see when and where the
639 events happened, as well as their re 405 events happened, as well as their results.
640 406
641 Say N if unsure. 407 Say N if unsure.
642 408
>> 409 config STACK_TRACER
>> 410 bool "Trace max stack"
>> 411 depends on HAVE_FUNCTION_TRACER
>> 412 select FUNCTION_TRACER
>> 413 select STACKTRACE
>> 414 select KALLSYMS
>> 415 help
>> 416 This special tracer records the maximum stack footprint of the
>> 417 kernel and displays it in /sys/kernel/debug/tracing/stack_trace.
>> 418
>> 419 This tracer works by hooking into every function call that the
>> 420 kernel executes, and keeping a maximum stack depth value and
>> 421 stack-trace saved. If this is configured with DYNAMIC_FTRACE
>> 422 then it will not have any overhead while the stack tracer
>> 423 is disabled.
>> 424
>> 425 To enable the stack tracer on bootup, pass in 'stacktrace'
>> 426 on the kernel command line.
>> 427
>> 428 The stack tracer can also be enabled or disabled via the
>> 429 sysctl kernel.stack_tracer_enabled
>> 430
>> 431 Say N if unsure.
>> 432
643 config BLK_DEV_IO_TRACE 433 config BLK_DEV_IO_TRACE
644 bool "Support for tracing block IO act 434 bool "Support for tracing block IO actions"
645 depends on SYSFS 435 depends on SYSFS
646 depends on BLOCK 436 depends on BLOCK
647 select RELAY 437 select RELAY
648 select DEBUG_FS 438 select DEBUG_FS
649 select TRACEPOINTS 439 select TRACEPOINTS
650 select GENERIC_TRACER 440 select GENERIC_TRACER
651 select STACKTRACE 441 select STACKTRACE
652 help 442 help
653 Say Y here if you want to be able to 443 Say Y here if you want to be able to trace the block layer actions
654 on a given queue. Tracing allows you 444 on a given queue. Tracing allows you to see any traffic happening
655 on a block device queue. For more in 445 on a block device queue. For more information (and the userspace
656 support tools needed), fetch the blk 446 support tools needed), fetch the blktrace tools from:
657 447
658 git://git.kernel.dk/blktrace.git 448 git://git.kernel.dk/blktrace.git
659 449
660 Tracing also is possible using the f 450 Tracing also is possible using the ftrace interface, e.g.:
661 451
662 echo 1 > /sys/block/sda/sda1/trace 452 echo 1 > /sys/block/sda/sda1/trace/enable
663 echo blk > /sys/kernel/tracing/cur !! 453 echo blk > /sys/kernel/debug/tracing/current_tracer
664 cat /sys/kernel/tracing/trace_pipe !! 454 cat /sys/kernel/debug/tracing/trace_pipe
665 455
666 If unsure, say N. 456 If unsure, say N.
667 457
668 config FPROBE_EVENTS <<
669 depends on FPROBE <<
670 depends on HAVE_REGS_AND_STACK_ACCESS_ <<
671 bool "Enable fprobe-based dynamic even <<
672 select TRACING <<
673 select PROBE_EVENTS <<
674 select DYNAMIC_EVENTS <<
675 default y <<
676 help <<
677 This allows user to add tracing even <<
678 exit via ftrace interface. The synta <<
679 and the kprobe events on function en <<
680 transparently converted to this fpro <<
681 <<
682 config PROBE_EVENTS_BTF_ARGS <<
683 depends on HAVE_FUNCTION_ARG_ACCESS_AP <<
684 depends on FPROBE_EVENTS || KPROBE_EVE <<
685 depends on DEBUG_INFO_BTF && BPF_SYSCA <<
686 bool "Support BTF function arguments f <<
687 default y <<
688 help <<
689 The user can specify the arguments o <<
690 of the arguments of the probed funct <<
691 kernel function entry or a tracepoin <<
692 This is available only if BTF (BPF T <<
693 <<
694 config KPROBE_EVENTS 458 config KPROBE_EVENTS
695 depends on KPROBES 459 depends on KPROBES
696 depends on HAVE_REGS_AND_STACK_ACCESS_ 460 depends on HAVE_REGS_AND_STACK_ACCESS_API
697 bool "Enable kprobes-based dynamic eve 461 bool "Enable kprobes-based dynamic events"
698 select TRACING 462 select TRACING
699 select PROBE_EVENTS 463 select PROBE_EVENTS
700 select DYNAMIC_EVENTS <<
701 default y 464 default y
702 help 465 help
703 This allows the user to add tracing 466 This allows the user to add tracing events (similar to tracepoints)
704 on the fly via the ftrace interface. 467 on the fly via the ftrace interface. See
705 Documentation/trace/kprobetrace.rst 468 Documentation/trace/kprobetrace.rst for more details.
706 469
707 Those events can be inserted whereve 470 Those events can be inserted wherever kprobes can probe, and record
708 various register and memory values. 471 various register and memory values.
709 472
710 This option is also required by perf 473 This option is also required by perf-probe subcommand of perf tools.
711 If you want to use perf tools, this 474 If you want to use perf tools, this option is strongly recommended.
712 475
713 config KPROBE_EVENTS_ON_NOTRACE 476 config KPROBE_EVENTS_ON_NOTRACE
714 bool "Do NOT protect notrace function 477 bool "Do NOT protect notrace function from kprobe events"
715 depends on KPROBE_EVENTS 478 depends on KPROBE_EVENTS
716 depends on DYNAMIC_FTRACE !! 479 depends on KPROBES_ON_FTRACE
717 default n 480 default n
718 help 481 help
719 This is only for the developers who 482 This is only for the developers who want to debug ftrace itself
720 using kprobe events. 483 using kprobe events.
721 484
722 If kprobes can use ftrace instead of 485 If kprobes can use ftrace instead of breakpoint, ftrace related
723 functions are protected from kprobe- !! 486 functions are protected from kprobe-events to prevent an infinit
724 recursion or any unexpected executio 487 recursion or any unexpected execution path which leads to a kernel
725 crash. 488 crash.
726 489
727 This option disables such protection 490 This option disables such protection and allows you to put kprobe
728 events on ftrace functions for debug 491 events on ftrace functions for debugging ftrace by itself.
729 Note that this might let you shoot y 492 Note that this might let you shoot yourself in the foot.
730 493
731 If unsure, say N. 494 If unsure, say N.
732 495
733 config UPROBE_EVENTS 496 config UPROBE_EVENTS
734 bool "Enable uprobes-based dynamic eve 497 bool "Enable uprobes-based dynamic events"
735 depends on ARCH_SUPPORTS_UPROBES 498 depends on ARCH_SUPPORTS_UPROBES
736 depends on MMU 499 depends on MMU
737 depends on PERF_EVENTS 500 depends on PERF_EVENTS
738 select UPROBES 501 select UPROBES
739 select PROBE_EVENTS 502 select PROBE_EVENTS
740 select DYNAMIC_EVENTS <<
741 select TRACING 503 select TRACING
742 default y 504 default y
743 help 505 help
744 This allows the user to add tracing 506 This allows the user to add tracing events on top of userspace
745 dynamic events (similar to tracepoin 507 dynamic events (similar to tracepoints) on the fly via the trace
746 events interface. Those events can b 508 events interface. Those events can be inserted wherever uprobes
747 can probe, and record various regist 509 can probe, and record various registers.
748 This option is required if you plan 510 This option is required if you plan to use perf-probe subcommand
749 of perf tools on user space applicat 511 of perf tools on user space applications.
750 512
751 config BPF_EVENTS 513 config BPF_EVENTS
752 depends on BPF_SYSCALL 514 depends on BPF_SYSCALL
753 depends on (KPROBE_EVENTS || UPROBE_EV 515 depends on (KPROBE_EVENTS || UPROBE_EVENTS) && PERF_EVENTS
754 bool 516 bool
755 default y 517 default y
756 help 518 help
757 This allows the user to attach BPF p !! 519 This allows the user to attach BPF programs to kprobe events.
758 tracepoint events. <<
759 <<
760 config DYNAMIC_EVENTS <<
761 def_bool n <<
762 520
763 config PROBE_EVENTS 521 config PROBE_EVENTS
764 def_bool n 522 def_bool n
765 523
>> 524 config DYNAMIC_FTRACE
>> 525 bool "enable/disable function tracing dynamically"
>> 526 depends on FUNCTION_TRACER
>> 527 depends on HAVE_DYNAMIC_FTRACE
>> 528 default y
>> 529 help
>> 530 This option will modify all the calls to function tracing
>> 531 dynamically (will patch them out of the binary image and
>> 532 replace them with a No-Op instruction) on boot up. During
>> 533 compile time, a table is made of all the locations that ftrace
>> 534 can function trace, and this table is linked into the kernel
>> 535 image. When this is enabled, functions can be individually
>> 536 enabled, and the functions not enabled will not affect
>> 537 performance of the system.
>> 538
>> 539 See the files in /sys/kernel/debug/tracing:
>> 540 available_filter_functions
>> 541 set_ftrace_filter
>> 542 set_ftrace_notrace
>> 543
>> 544 This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but
>> 545 otherwise has native performance as long as no tracing is active.
>> 546
>> 547 config DYNAMIC_FTRACE_WITH_REGS
>> 548 def_bool y
>> 549 depends on DYNAMIC_FTRACE
>> 550 depends on HAVE_DYNAMIC_FTRACE_WITH_REGS
>> 551
>> 552 config FUNCTION_PROFILER
>> 553 bool "Kernel function profiler"
>> 554 depends on FUNCTION_TRACER
>> 555 default n
>> 556 help
>> 557 This option enables the kernel function profiler. A file is created
>> 558 in debugfs called function_profile_enabled which defaults to zero.
>> 559 When a 1 is echoed into this file profiling begins, and when a
>> 560 zero is entered, profiling stops. A "functions" file is created in
>> 561 the trace_stat directory; this file shows the list of functions that
>> 562 have been hit and their counters.
>> 563
>> 564 If in doubt, say N.
>> 565
766 config BPF_KPROBE_OVERRIDE 566 config BPF_KPROBE_OVERRIDE
767 bool "Enable BPF programs to override 567 bool "Enable BPF programs to override a kprobed function"
768 depends on BPF_EVENTS 568 depends on BPF_EVENTS
769 depends on FUNCTION_ERROR_INJECTION 569 depends on FUNCTION_ERROR_INJECTION
770 default n 570 default n
771 help 571 help
772 Allows BPF to override the execution 572 Allows BPF to override the execution of a probed function and
773 set a different return value. This i 573 set a different return value. This is used for error injection.
774 574
775 config FTRACE_MCOUNT_RECORD 575 config FTRACE_MCOUNT_RECORD
776 def_bool y 576 def_bool y
777 depends on DYNAMIC_FTRACE 577 depends on DYNAMIC_FTRACE
778 depends on HAVE_FTRACE_MCOUNT_RECORD 578 depends on HAVE_FTRACE_MCOUNT_RECORD
779 579
780 config FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_EN !! 580 config FTRACE_SELFTEST
781 bool 581 bool
782 depends on FTRACE_MCOUNT_RECORD <<
783 582
784 config FTRACE_MCOUNT_USE_CC !! 583 config FTRACE_STARTUP_TEST
785 def_bool y !! 584 bool "Perform a startup test on ftrace"
786 depends on $(cc-option,-mrecord-mcount !! 585 depends on GENERIC_TRACER
787 depends on !FTRACE_MCOUNT_USE_PATCHABL !! 586 select FTRACE_SELFTEST
788 depends on FTRACE_MCOUNT_RECORD !! 587 help
>> 588 This option performs a series of startup tests on ftrace. On bootup
>> 589 a series of tests are made to verify that the tracer is
>> 590 functioning properly. It will do tests on all the configured
>> 591 tracers of ftrace.
789 592
790 config FTRACE_MCOUNT_USE_OBJTOOL !! 593 config EVENT_TRACE_TEST_SYSCALLS
791 def_bool y !! 594 bool "Run selftest on syscall events"
792 depends on HAVE_OBJTOOL_MCOUNT !! 595 depends on FTRACE_STARTUP_TEST
793 depends on !FTRACE_MCOUNT_USE_PATCHABL !! 596 help
794 depends on !FTRACE_MCOUNT_USE_CC !! 597 This option will also enable testing every syscall event.
795 depends on FTRACE_MCOUNT_RECORD !! 598 It only enables the event and disables it and runs various loads
796 select OBJTOOL !! 599 with the event enabled. This adds a bit more time for kernel boot
>> 600 up since it runs this on every system call defined.
797 601
798 config FTRACE_MCOUNT_USE_RECORDMCOUNT !! 602 TBD - enable a way to actually call the syscalls as we test their
799 def_bool y !! 603 events
800 depends on !FTRACE_MCOUNT_USE_PATCHABL !! 604
801 depends on !FTRACE_MCOUNT_USE_CC !! 605 config MMIOTRACE
802 depends on !FTRACE_MCOUNT_USE_OBJTOOL !! 606 bool "Memory mapped IO tracing"
803 depends on FTRACE_MCOUNT_RECORD !! 607 depends on HAVE_MMIOTRACE_SUPPORT && PCI
>> 608 select GENERIC_TRACER
>> 609 help
>> 610 Mmiotrace traces Memory Mapped I/O access and is meant for
>> 611 debugging and reverse engineering. It is called from the ioremap
>> 612 implementation and works via page faults. Tracing is disabled by
>> 613 default and can be enabled at run-time.
>> 614
>> 615 See Documentation/trace/mmiotrace.rst.
>> 616 If you are not helping to develop drivers, say N.
804 617
805 config TRACING_MAP 618 config TRACING_MAP
806 bool 619 bool
807 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG 620 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
808 help 621 help
809 tracing_map is a special-purpose loc 622 tracing_map is a special-purpose lock-free map for tracing,
810 separated out as a stand-alone facil 623 separated out as a stand-alone facility in order to allow it
811 to be shared between multiple tracer 624 to be shared between multiple tracers. It isn't meant to be
812 generally used outside of that conte 625 generally used outside of that context, and is normally
813 selected by tracers that use it. 626 selected by tracers that use it.
814 627
815 config SYNTH_EVENTS <<
816 bool "Synthetic trace events" <<
817 select TRACING <<
818 select DYNAMIC_EVENTS <<
819 default n <<
820 help <<
821 Synthetic events are user-defined tr <<
822 used to combine data from other trac <<
823 data source. Synthetic events can b <<
824 via the trace() action of histogram <<
825 by way of an in-kernel API. <<
826 <<
827 See Documentation/trace/events.rst o <<
828 Documentation/trace/histogram.rst fo <<
829 <<
830 If in doubt, say N. <<
831 <<
832 config USER_EVENTS <<
833 bool "User trace events" <<
834 select TRACING <<
835 select DYNAMIC_EVENTS <<
836 help <<
837 User trace events are user-defined t <<
838 can be used like an existing kernel <<
839 events are generated by writing to a <<
840 processes can determine if their tra <<
841 generated by registering a value and <<
842 that reflects when it is enabled or <<
843 <<
844 See Documentation/trace/user_events. <<
845 If in doubt, say N. <<
846 <<
847 config HIST_TRIGGERS 628 config HIST_TRIGGERS
848 bool "Histogram triggers" 629 bool "Histogram triggers"
849 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG 630 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
850 select TRACING_MAP 631 select TRACING_MAP
851 select TRACING 632 select TRACING
852 select DYNAMIC_EVENTS <<
853 select SYNTH_EVENTS <<
854 default n 633 default n
855 help 634 help
856 Hist triggers allow one or more arbi 635 Hist triggers allow one or more arbitrary trace event fields
857 to be aggregated into hash tables an 636 to be aggregated into hash tables and dumped to stdout by
858 reading a debugfs/tracefs file. The 637 reading a debugfs/tracefs file. They're useful for
859 gathering quick and dirty (though pr 638 gathering quick and dirty (though precise) summaries of
860 event activity as an initial guide f 639 event activity as an initial guide for further investigation
861 using more advanced tools. 640 using more advanced tools.
862 641
863 Inter-event tracing of quantities su 642 Inter-event tracing of quantities such as latencies is also
864 supported using hist triggers under 643 supported using hist triggers under this option.
865 644
866 See Documentation/trace/histogram.rs 645 See Documentation/trace/histogram.rst.
867 If in doubt, say N. 646 If in doubt, say N.
868 647
869 config TRACE_EVENT_INJECT !! 648 config MMIOTRACE_TEST
870 bool "Trace event injection" !! 649 tristate "Test module for mmiotrace"
871 depends on TRACING !! 650 depends on MMIOTRACE && m
872 help 651 help
873 Allow user-space to inject a specifi !! 652 This is a dumb module for testing mmiotrace. It is very dangerous
874 buffer. This is mainly used for test !! 653 as it will write garbage to IO memory starting at a given address.
>> 654 However, it should be safe to use on e.g. unused portion of VRAM.
875 655
876 If unsure, say N. !! 656 Say N, unless you absolutely know what you are doing.
877 657
878 config TRACEPOINT_BENCHMARK 658 config TRACEPOINT_BENCHMARK
879 bool "Add tracepoint that benchmarks t !! 659 bool "Add tracepoint that benchmarks tracepoints"
880 help 660 help
881 This option creates the tracepoint "b 661 This option creates the tracepoint "benchmark:benchmark_event".
882 When the tracepoint is enabled, it ki 662 When the tracepoint is enabled, it kicks off a kernel thread that
883 goes into an infinite loop (calling c !! 663 goes into an infinite loop (calling cond_sched() to let other tasks
884 run), and calls the tracepoint. Each 664 run), and calls the tracepoint. Each iteration will record the time
885 it took to write to the tracepoint an 665 it took to write to the tracepoint and the next iteration that
886 data will be passed to the tracepoint 666 data will be passed to the tracepoint itself. That is, the tracepoint
887 will report the time it took to do th 667 will report the time it took to do the previous tracepoint.
888 The string written to the tracepoint 668 The string written to the tracepoint is a static string of 128 bytes
889 to keep the time the same. The initia 669 to keep the time the same. The initial string is simply a write of
890 "START". The second string records th 670 "START". The second string records the cold cache time of the first
891 write which is not added to the rest 671 write which is not added to the rest of the calculations.
892 672
893 As it is a tight loop, it benchmarks 673 As it is a tight loop, it benchmarks as hot cache. That's fine because
894 we care most about hot paths that are 674 we care most about hot paths that are probably in cache already.
895 675
896 An example of the output: 676 An example of the output:
897 677
898 START 678 START
899 first=3672 [COLD CACHED] 679 first=3672 [COLD CACHED]
900 last=632 first=3672 max=632 min= 680 last=632 first=3672 max=632 min=632 avg=316 std=446 std^2=199712
901 last=278 first=3672 max=632 min= 681 last=278 first=3672 max=632 min=278 avg=303 std=316 std^2=100337
902 last=277 first=3672 max=632 min= 682 last=277 first=3672 max=632 min=277 avg=296 std=258 std^2=67064
903 last=273 first=3672 max=632 min= 683 last=273 first=3672 max=632 min=273 avg=292 std=224 std^2=50411
904 last=273 first=3672 max=632 min= 684 last=273 first=3672 max=632 min=273 avg=288 std=200 std^2=40389
905 last=281 first=3672 max=632 min= 685 last=281 first=3672 max=632 min=273 avg=287 std=183 std^2=33666
906 686
907 687
908 config RING_BUFFER_BENCHMARK 688 config RING_BUFFER_BENCHMARK
909 tristate "Ring buffer benchmark stress 689 tristate "Ring buffer benchmark stress tester"
910 depends on RING_BUFFER 690 depends on RING_BUFFER
911 help 691 help
912 This option creates a test to stress 692 This option creates a test to stress the ring buffer and benchmark it.
913 It creates its own ring buffer such 693 It creates its own ring buffer such that it will not interfere with
914 any other users of the ring buffer ( 694 any other users of the ring buffer (such as ftrace). It then creates
915 a producer and consumer that will ru 695 a producer and consumer that will run for 10 seconds and sleep for
916 10 seconds. Each interval it will pr 696 10 seconds. Each interval it will print out the number of events
917 it recorded and give a rough estimat 697 it recorded and give a rough estimate of how long each iteration took.
918 698
919 It does not disable interrupts or ra 699 It does not disable interrupts or raise its priority, so it may be
920 affected by processes that are runni 700 affected by processes that are running.
921 701
922 If unsure, say N. 702 If unsure, say N.
923 703
924 config TRACE_EVAL_MAP_FILE <<
925 bool "Show eval mappings for trace even <<
926 depends on TRACING <<
927 help <<
928 The "print fmt" of the trace events wi <<
929 instead of their values. This can caus <<
930 that use this string to parse the raw <<
931 how to convert the string to its value <<
932 <<
933 To fix this, there's a special macro i <<
934 to convert an enum/sizeof into its val <<
935 the print fmt strings will be converte <<
936 <<
937 If something does not get converted pr <<
938 used to show what enums/sizeof the ker <<
939 <<
940 This option is for debugging the conve <<
941 in the tracing directory called "eval_ <<
942 names matched with their values and wh <<
943 belong too. <<
944 <<
945 Normally, the mapping of the strings t <<
946 boot up or module load. With this opti <<
947 they are needed for the "eval_map" fil <<
948 increase the memory footprint of the r <<
949 <<
950 If unsure, say N. <<
951 <<
952 config FTRACE_RECORD_RECURSION <<
953 bool "Record functions that recurse in <<
954 depends on FUNCTION_TRACER <<
955 help <<
956 All callbacks that attach to the fun <<
957 of protection against recursion. Eve <<
958 it adds overhead. This option will c <<
959 file system called "recursed_functio <<
960 that triggered a recursion. <<
961 <<
962 This will add more overhead to cases <<
963 <<
964 If unsure, say N <<
965 <<
966 config FTRACE_RECORD_RECURSION_SIZE <<
967 int "Max number of recursed functions <<
968 default 128 <<
969 depends on FTRACE_RECORD_RECURSION <<
970 help <<
971 This defines the limit of number of <<
972 listed in the "recursed_functions" f <<
973 the functions that caused a recursio <<
974 This file can be reset, but the limi <<
975 size at runtime. <<
976 <<
977 config FTRACE_VALIDATE_RCU_IS_WATCHING <<
978 bool "Validate RCU is on during ftrace <<
979 depends on FUNCTION_TRACER <<
980 depends on ARCH_WANTS_NO_INSTR <<
981 help <<
982 All callbacks that attach to the fun <<
983 protection against recursion. This o <<
984 ftrace (and other users of ftrace_te <<
985 called outside of RCU, as if they ar <<
986 also has a noticeable overhead when <<
987 <<
988 If unsure, say N <<
989 <<
990 config RING_BUFFER_RECORD_RECURSION <<
991 bool "Record functions that recurse in <<
992 depends on FTRACE_RECORD_RECURSION <<
993 # default y, because it is coupled wit <<
994 default y <<
995 help <<
996 The ring buffer has its own internal <<
997 recursion happens it won't cause har <<
998 but it does cause unwanted overhead. <<
999 place where recursion was detected i <<
1000 file. <<
1001 <<
1002 This will add more overhead to case <<
1003 <<
1004 config GCOV_PROFILE_FTRACE <<
1005 bool "Enable GCOV profiling on ftrace <<
1006 depends on GCOV_KERNEL <<
1007 help <<
1008 Enable GCOV profiling on ftrace sub <<
1009 which functions/lines are tested. <<
1010 <<
1011 If unsure, say N. <<
1012 <<
1013 Note that on a kernel compiled with <<
1014 run significantly slower. <<
1015 <<
1016 config FTRACE_SELFTEST <<
1017 bool <<
1018 <<
1019 config FTRACE_STARTUP_TEST <<
1020 bool "Perform a startup test on ftrac <<
1021 depends on GENERIC_TRACER <<
1022 select FTRACE_SELFTEST <<
1023 help <<
1024 This option performs a series of st <<
1025 a series of tests are made to verif <<
1026 functioning properly. It will do te <<
1027 tracers of ftrace. <<
1028 <<
1029 config EVENT_TRACE_STARTUP_TEST <<
1030 bool "Run selftest on trace events" <<
1031 depends on FTRACE_STARTUP_TEST <<
1032 default y <<
1033 help <<
1034 This option performs a test on all <<
1035 It basically just enables each even <<
1036 will trigger events (not necessaril <<
1037 This may take some time run as ther <<
1038 <<
1039 config EVENT_TRACE_TEST_SYSCALLS <<
1040 bool "Run selftest on syscall events" <<
1041 depends on EVENT_TRACE_STARTUP_TEST <<
1042 help <<
1043 This option will also enable testing <<
1044 It only enables the event and disabl <<
1045 with the event enabled. This adds a <<
1046 up since it runs this on every syste <<
1047 <<
1048 TBD - enable a way to actually call <<
1049 events <<
1050 <<
1051 config FTRACE_SORT_STARTUP_TEST <<
1052 bool "Verify compile time sorting of f <<
1053 depends on DYNAMIC_FTRACE <<
1054 depends on BUILDTIME_MCOUNT_SORT <<
1055 help <<
1056 Sorting of the mcount_loc sections t <<
1057 where the ftrace knows where to patc <<
1058 and other callbacks is done at compi <<
1059 is not done correctly, it will cause <<
1060 When this is set, the sorted section <<
1061 are in deed sorted and will warn if <<
1062 <<
1063 If unsure, say N <<
1064 <<
1065 config RING_BUFFER_STARTUP_TEST 704 config RING_BUFFER_STARTUP_TEST
1066 bool "Ring buffer startup self test" 705 bool "Ring buffer startup self test"
1067 depends on RING_BUFFER 706 depends on RING_BUFFER
1068 help 707 help
1069 Run a simple self test on the ring b !! 708 Run a simple self test on the ring buffer on boot up. Late in the
1070 kernel boot sequence, the test will 709 kernel boot sequence, the test will start that kicks off
1071 a thread per cpu. Each thread will w 710 a thread per cpu. Each thread will write various size events
1072 into the ring buffer. Another thread 711 into the ring buffer. Another thread is created to send IPIs
1073 to each of the threads, where the IP 712 to each of the threads, where the IPI handler will also write
1074 to the ring buffer, to test/stress t 713 to the ring buffer, to test/stress the nesting ability.
1075 If any anomalies are discovered, a w 714 If any anomalies are discovered, a warning will be displayed
1076 and all ring buffers will be disable 715 and all ring buffers will be disabled.
1077 716
1078 The test runs for 10 seconds. This w 717 The test runs for 10 seconds. This will slow your boot time
1079 by at least 10 more seconds. 718 by at least 10 more seconds.
1080 719
1081 At the end of the test, statistics a !! 720 At the end of the test, statics and more checks are done.
1082 It will output the stats of each per !! 721 It will output the stats of each per cpu buffer. What
1083 was written, the sizes, what was rea 722 was written, the sizes, what was read, what was lost, and
1084 other similar details. 723 other similar details.
1085 724
1086 If unsure, say N 725 If unsure, say N
1087 726
1088 config RING_BUFFER_VALIDATE_TIME_DELTAS <<
1089 bool "Verify ring buffer time stamp d <<
1090 depends on RING_BUFFER <<
1091 help <<
1092 This will audit the time stamps on <<
1093 buffer to make sure that all the ti <<
1094 events on a sub buffer matches the <<
1095 This audit is performed for every e <<
1096 interrupted, or interrupting anothe <<
1097 is also made when traversing sub bu <<
1098 that all the deltas on the previous <<
1099 add up to be greater than the curre <<
1100 <<
1101 NOTE: This adds significant overhea <<
1102 and should only be used to test the <<
1103 Do not use it on production systems <<
1104 <<
1105 Only say Y if you understand what t <<
1106 still want it enabled. Otherwise sa <<
1107 <<
1108 config MMIOTRACE_TEST <<
1109 tristate "Test module for mmiotrace" <<
1110 depends on MMIOTRACE && m <<
1111 help <<
1112 This is a dumb module for testing m <<
1113 as it will write garbage to IO memo <<
1114 However, it should be safe to use o <<
1115 <<
1116 Say N, unless you absolutely know w <<
1117 <<
1118 config PREEMPTIRQ_DELAY_TEST 727 config PREEMPTIRQ_DELAY_TEST
1119 tristate "Test module to create a pre !! 728 tristate "Preempt / IRQ disable delay thread to test latency tracers"
1120 depends on m 729 depends on m
1121 help 730 help
1122 Select this option to build a test 731 Select this option to build a test module that can help test latency
1123 tracers by executing a preempt or i 732 tracers by executing a preempt or irq disable section with a user
1124 configurable delay. The module busy 733 configurable delay. The module busy waits for the duration of the
1125 critical section. 734 critical section.
1126 735
1127 For example, the following invocati !! 736 For example, the following invocation forces a one-time irq-disabled
1128 irq-disabled critical sections for !! 737 critical section for 500us:
1129 modprobe preemptirq_delay_test test !! 738 modprobe preemptirq_delay_test test_mode=irq delay=500000
1130 <<
1131 What's more, if you want to attach <<
1132 tracer is running on, specify cpu_a <<
1133 command. <<
1134 739
1135 If unsure, say N 740 If unsure, say N
1136 741
1137 config SYNTH_EVENT_GEN_TEST !! 742 config TRACE_EVAL_MAP_FILE
1138 tristate "Test module for in-kernel s !! 743 bool "Show eval mappings for trace events"
1139 depends on SYNTH_EVENTS && m !! 744 depends on TRACING
1140 help !! 745 help
1141 This option creates a test module t !! 746 The "print fmt" of the trace events will show the enum/sizeof names
1142 functionality of in-kernel syntheti !! 747 instead of their values. This can cause problems for user space tools
1143 generation. !! 748 that use this string to parse the raw data as user space does not know
>> 749 how to convert the string to its value.
1144 750
1145 To test, insert the module, and the !! 751 To fix this, there's a special macro in the kernel that can be used
1146 for the generated sample events. !! 752 to convert an enum/sizeof into its value. If this macro is used, then
>> 753 the print fmt strings will be converted to their values.
1147 754
1148 If unsure, say N. !! 755 If something does not get converted properly, this option can be
>> 756 used to show what enums/sizeof the kernel tried to convert.
1149 757
1150 config KPROBE_EVENT_GEN_TEST !! 758 This option is for debugging the conversions. A file is created
1151 tristate "Test module for in-kernel k !! 759 in the tracing directory called "eval_map" that will show the
1152 depends on KPROBE_EVENTS && m !! 760 names matched with their values and what trace event system they
1153 help !! 761 belong too.
1154 This option creates a test module t <<
1155 functionality of in-kernel kprobe e <<
1156 762
1157 To test, insert the module, and the !! 763 Normally, the mapping of the strings to values will be freed after
1158 for the generated kprobe events. !! 764 boot up or module load. With this option, they will not be freed, as
>> 765 they are needed for the "eval_map" file. Enabling this option will
>> 766 increase the memory footprint of the running kernel.
1159 767
1160 If unsure, say N. !! 768 If unsure, say N
1161 769
1162 config HIST_TRIGGERS_DEBUG !! 770 config TRACING_EVENTS_GPIO
1163 bool "Hist trigger debug support" !! 771 bool "Trace gpio events"
1164 depends on HIST_TRIGGERS !! 772 depends on GPIOLIB
>> 773 default y
1165 help 774 help
1166 Add "hist_debug" file for each even !! 775 Enable tracing events for gpio subsystem
1167 dump out a bunch of internal detail <<
1168 defined on that event. <<
1169 776
1170 The hist_debug file serves a couple !! 777 config GCOV_PROFILE_FTRACE
1171 !! 778 bool "Enable GCOV profiling on ftrace subsystem"
1172 - Helps developers verify that no !! 779 depends on GCOV_KERNEL
>> 780 help
>> 781 Enable GCOV profiling on ftrace subsystem for checking
>> 782 which functions/lines are tested.
1173 783
1174 - Provides educational informatio !! 784 If unsure, say N.
1175 of the hist trigger internals a <<
1176 Documentation/trace/histogram-d <<
1177 785
1178 The hist_debug output only covers t !! 786 Note that on a kernel compiled with this config, ftrace will
1179 related to the histogram definition !! 787 run significantly slower.
1180 display the internals of map bucket <<
1181 running histograms. <<
1182 788
1183 If unsure, say N. !! 789 endif # FTRACE
1184 790
1185 source "kernel/trace/rv/Kconfig" !! 791 endif # TRACING_SUPPORT
1186 792
1187 endif # FTRACE <<
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