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