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