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