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