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