1# 2# Architectures that offer an FUNCTION_TRACER implementation should 3# select HAVE_FUNCTION_TRACER: 4# 5 6config USER_STACKTRACE_SUPPORT 7 bool 8 9config NOP_TRACER 10 bool 11 12config HAVE_FTRACE_NMI_ENTER 13 bool 14 help 15 See Documentation/trace/ftrace-design.txt 16 17config HAVE_FUNCTION_TRACER 18 bool 19 help 20 See Documentation/trace/ftrace-design.txt 21 22config HAVE_FUNCTION_GRAPH_TRACER 23 bool 24 help 25 See Documentation/trace/ftrace-design.txt 26 27config HAVE_FUNCTION_GRAPH_FP_TEST 28 bool 29 help 30 See Documentation/trace/ftrace-design.txt 31 32config HAVE_DYNAMIC_FTRACE 33 bool 34 help 35 See Documentation/trace/ftrace-design.txt 36 37config HAVE_DYNAMIC_FTRACE_WITH_REGS 38 bool 39 40config HAVE_FTRACE_MCOUNT_RECORD 41 bool 42 help 43 See Documentation/trace/ftrace-design.txt 44 45config HAVE_SYSCALL_TRACEPOINTS 46 bool 47 help 48 See Documentation/trace/ftrace-design.txt 49 50config HAVE_FENTRY 51 bool 52 help 53 Arch supports the gcc options -pg with -mfentry 54 55config HAVE_C_RECORDMCOUNT 56 bool 57 help 58 C version of recordmcount available? 59 60config TRACER_MAX_TRACE 61 bool 62 63config TRACE_CLOCK 64 bool 65 66config RING_BUFFER 67 bool 68 select TRACE_CLOCK 69 select IRQ_WORK 70 71config FTRACE_NMI_ENTER 72 bool 73 depends on HAVE_FTRACE_NMI_ENTER 74 default y 75 76config EVENT_TRACING 77 select CONTEXT_SWITCH_TRACER 78 bool 79 80config CONTEXT_SWITCH_TRACER 81 bool 82 83config RING_BUFFER_ALLOW_SWAP 84 bool 85 help 86 Allow the use of ring_buffer_swap_cpu. 87 Adds a very slight overhead to tracing when enabled. 88 89# All tracer options should select GENERIC_TRACER. For those options that are 90# enabled by all tracers (context switch and event tracer) they select TRACING. 91# This allows those options to appear when no other tracer is selected. But the 92# options do not appear when something else selects it. We need the two options 93# GENERIC_TRACER and TRACING to avoid circular dependencies to accomplish the 94# hiding of the automatic options. 95 96config TRACING 97 bool 98 select DEBUG_FS 99 select RING_BUFFER 100 select STACKTRACE if STACKTRACE_SUPPORT 101 select TRACEPOINTS 102 select NOP_TRACER 103 select BINARY_PRINTF 104 select EVENT_TRACING 105 select TRACE_CLOCK 106 107config GENERIC_TRACER 108 bool 109 select TRACING 110 111# 112# Minimum requirements an architecture has to meet for us to 113# be able to offer generic tracing facilities: 114# 115config TRACING_SUPPORT 116 bool 117 # PPC32 has no irqflags tracing support, but it can use most of the 118 # tracers anyway, they were tested to build and work. Note that new 119 # exceptions to this list aren't welcomed, better implement the 120 # irqflags tracing for your architecture. 121 depends on TRACE_IRQFLAGS_SUPPORT || PPC32 122 depends on STACKTRACE_SUPPORT 123 default y 124 125if TRACING_SUPPORT 126 127menuconfig FTRACE 128 bool "Tracers" 129 default y if DEBUG_KERNEL 130 help 131 Enable the kernel tracing infrastructure. 132 133if FTRACE 134 135config FUNCTION_TRACER 136 bool "Kernel Function Tracer" 137 depends on HAVE_FUNCTION_TRACER 138 select KALLSYMS 139 select GENERIC_TRACER 140 select CONTEXT_SWITCH_TRACER 141 help 142 Enable the kernel to trace every kernel function. This is done 143 by using a compiler feature to insert a small, 5-byte No-Operation 144 instruction at the beginning of every kernel function, which NOP 145 sequence is then dynamically patched into a tracer call when 146 tracing is enabled by the administrator. If it's runtime disabled 147 (the bootup default), then the overhead of the instructions is very 148 small and not measurable even in micro-benchmarks. 149 150config FUNCTION_GRAPH_TRACER 151 bool "Kernel Function Graph Tracer" 152 depends on HAVE_FUNCTION_GRAPH_TRACER 153 depends on FUNCTION_TRACER 154 depends on !X86_32 || !CC_OPTIMIZE_FOR_SIZE 155 default y 156 help 157 Enable the kernel to trace a function at both its return 158 and its entry. 159 Its first purpose is to trace the duration of functions and 160 draw a call graph for each thread with some information like 161 the return value. This is done by setting the current return 162 address on the current task structure into a stack of calls. 163 164 165config IRQSOFF_TRACER 166 bool "Interrupts-off Latency Tracer" 167 default n 168 depends on TRACE_IRQFLAGS_SUPPORT 169 depends on !ARCH_USES_GETTIMEOFFSET 170 select TRACE_IRQFLAGS 171 select GENERIC_TRACER 172 select TRACER_MAX_TRACE 173 select RING_BUFFER_ALLOW_SWAP 174 select TRACER_SNAPSHOT 175 select TRACER_SNAPSHOT_PER_CPU_SWAP 176 help 177 This option measures the time spent in irqs-off critical 178 sections, with microsecond accuracy. 179 180 The default measurement method is a maximum search, which is 181 disabled by default and can be runtime (re-)started 182 via: 183 184 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency 185 186 (Note that kernel size and overhead increase with this option 187 enabled. This option and the preempt-off timing option can be 188 used together or separately.) 189 190config PREEMPT_TRACER 191 bool "Preemption-off Latency Tracer" 192 default n 193 depends on !ARCH_USES_GETTIMEOFFSET 194 depends on PREEMPT 195 select GENERIC_TRACER 196 select TRACER_MAX_TRACE 197 select RING_BUFFER_ALLOW_SWAP 198 select TRACER_SNAPSHOT 199 select TRACER_SNAPSHOT_PER_CPU_SWAP 200 help 201 This option measures the time spent in preemption-off critical 202 sections, with microsecond accuracy. 203 204 The default measurement method is a maximum search, which is 205 disabled by default and can be runtime (re-)started 206 via: 207 208 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency 209 210 (Note that kernel size and overhead increase with this option 211 enabled. This option and the irqs-off timing option can be 212 used together or separately.) 213 214config SCHED_TRACER 215 bool "Scheduling Latency Tracer" 216 select GENERIC_TRACER 217 select CONTEXT_SWITCH_TRACER 218 select TRACER_MAX_TRACE 219 select TRACER_SNAPSHOT 220 help 221 This tracer tracks the latency of the highest priority task 222 to be scheduled in, starting from the point it has woken up. 223 224config ENABLE_DEFAULT_TRACERS 225 bool "Trace process context switches and events" 226 depends on !GENERIC_TRACER 227 select TRACING 228 help 229 This tracer hooks to various trace points in the kernel, 230 allowing the user to pick and choose which trace point they 231 want to trace. It also includes the sched_switch tracer plugin. 232 233config FTRACE_SYSCALLS 234 bool "Trace syscalls" 235 depends on HAVE_SYSCALL_TRACEPOINTS 236 select GENERIC_TRACER 237 select KALLSYMS 238 help 239 Basic tracer to catch the syscall entry and exit events. 240 241config TRACER_SNAPSHOT 242 bool "Create a snapshot trace buffer" 243 select TRACER_MAX_TRACE 244 help 245 Allow tracing users to take snapshot of the current buffer using the 246 ftrace interface, e.g.: 247 248 echo 1 > /sys/kernel/debug/tracing/snapshot 249 cat snapshot 250 251config TRACER_SNAPSHOT_PER_CPU_SWAP 252 bool "Allow snapshot to swap per CPU" 253 depends on TRACER_SNAPSHOT 254 select RING_BUFFER_ALLOW_SWAP 255 help 256 Allow doing a snapshot of a single CPU buffer instead of a 257 full swap (all buffers). If this is set, then the following is 258 allowed: 259 260 echo 1 > /sys/kernel/debug/tracing/per_cpu/cpu2/snapshot 261 262 After which, only the tracing buffer for CPU 2 was swapped with 263 the main tracing buffer, and the other CPU buffers remain the same. 264 265 When this is enabled, this adds a little more overhead to the 266 trace recording, as it needs to add some checks to synchronize 267 recording with swaps. But this does not affect the performance 268 of the overall system. This is enabled by default when the preempt 269 or irq latency tracers are enabled, as those need to swap as well 270 and already adds the overhead (plus a lot more). 271 272config TRACE_BRANCH_PROFILING 273 bool 274 select GENERIC_TRACER 275 276choice 277 prompt "Branch Profiling" 278 default BRANCH_PROFILE_NONE 279 help 280 The branch profiling is a software profiler. It will add hooks 281 into the C conditionals to test which path a branch takes. 282 283 The likely/unlikely profiler only looks at the conditions that 284 are annotated with a likely or unlikely macro. 285 286 The "all branch" profiler will profile every if-statement in the 287 kernel. This profiler will also enable the likely/unlikely 288 profiler. 289 290 Either of the above profilers adds a bit of overhead to the system. 291 If unsure, choose "No branch profiling". 292 293config BRANCH_PROFILE_NONE 294 bool "No branch profiling" 295 help 296 No branch profiling. Branch profiling adds a bit of overhead. 297 Only enable it if you want to analyse the branching behavior. 298 Otherwise keep it disabled. 299 300config PROFILE_ANNOTATED_BRANCHES 301 bool "Trace likely/unlikely profiler" 302 select TRACE_BRANCH_PROFILING 303 help 304 This tracer profiles all likely and unlikely macros 305 in the kernel. It will display the results in: 306 307 /sys/kernel/debug/tracing/trace_stat/branch_annotated 308 309 Note: this will add a significant overhead; only turn this 310 on if you need to profile the system's use of these macros. 311 312config PROFILE_ALL_BRANCHES 313 bool "Profile all if conditionals" 314 select TRACE_BRANCH_PROFILING 315 help 316 This tracer profiles all branch conditions. Every if () 317 taken in the kernel is recorded whether it hit or miss. 318 The results will be displayed in: 319 320 /sys/kernel/debug/tracing/trace_stat/branch_all 321 322 This option also enables the likely/unlikely profiler. 323 324 This configuration, when enabled, will impose a great overhead 325 on the system. This should only be enabled when the system 326 is to be analyzed in much detail. 327endchoice 328 329config TRACING_BRANCHES 330 bool 331 help 332 Selected by tracers that will trace the likely and unlikely 333 conditions. This prevents the tracers themselves from being 334 profiled. Profiling the tracing infrastructure can only happen 335 when the likelys and unlikelys are not being traced. 336 337config BRANCH_TRACER 338 bool "Trace likely/unlikely instances" 339 depends on TRACE_BRANCH_PROFILING 340 select TRACING_BRANCHES 341 help 342 This traces the events of likely and unlikely condition 343 calls in the kernel. The difference between this and the 344 "Trace likely/unlikely profiler" is that this is not a 345 histogram of the callers, but actually places the calling 346 events into a running trace buffer to see when and where the 347 events happened, as well as their results. 348 349 Say N if unsure. 350 351config STACK_TRACER 352 bool "Trace max stack" 353 depends on HAVE_FUNCTION_TRACER 354 select FUNCTION_TRACER 355 select STACKTRACE 356 select KALLSYMS 357 help 358 This special tracer records the maximum stack footprint of the 359 kernel and displays it in /sys/kernel/debug/tracing/stack_trace. 360 361 This tracer works by hooking into every function call that the 362 kernel executes, and keeping a maximum stack depth value and 363 stack-trace saved. If this is configured with DYNAMIC_FTRACE 364 then it will not have any overhead while the stack tracer 365 is disabled. 366 367 To enable the stack tracer on bootup, pass in 'stacktrace' 368 on the kernel command line. 369 370 The stack tracer can also be enabled or disabled via the 371 sysctl kernel.stack_tracer_enabled 372 373 Say N if unsure. 374 375config BLK_DEV_IO_TRACE 376 bool "Support for tracing block IO actions" 377 depends on SYSFS 378 depends on BLOCK 379 select RELAY 380 select DEBUG_FS 381 select TRACEPOINTS 382 select GENERIC_TRACER 383 select STACKTRACE 384 help 385 Say Y here if you want to be able to trace the block layer actions 386 on a given queue. Tracing allows you to see any traffic happening 387 on a block device queue. For more information (and the userspace 388 support tools needed), fetch the blktrace tools from: 389 390 git://git.kernel.dk/blktrace.git 391 392 Tracing also is possible using the ftrace interface, e.g.: 393 394 echo 1 > /sys/block/sda/sda1/trace/enable 395 echo blk > /sys/kernel/debug/tracing/current_tracer 396 cat /sys/kernel/debug/tracing/trace_pipe 397 398 If unsure, say N. 399 400config KPROBE_EVENT 401 depends on KPROBES 402 depends on HAVE_REGS_AND_STACK_ACCESS_API 403 bool "Enable kprobes-based dynamic events" 404 select TRACING 405 select PROBE_EVENTS 406 default y 407 help 408 This allows the user to add tracing events (similar to tracepoints) 409 on the fly via the ftrace interface. See 410 Documentation/trace/kprobetrace.txt for more details. 411 412 Those events can be inserted wherever kprobes can probe, and record 413 various register and memory values. 414 415 This option is also required by perf-probe subcommand of perf tools. 416 If you want to use perf tools, this option is strongly recommended. 417 418config UPROBE_EVENT 419 bool "Enable uprobes-based dynamic events" 420 depends on ARCH_SUPPORTS_UPROBES 421 depends on MMU 422 depends on PERF_EVENTS 423 select UPROBES 424 select PROBE_EVENTS 425 select TRACING 426 default n 427 help 428 This allows the user to add tracing events on top of userspace 429 dynamic events (similar to tracepoints) on the fly via the trace 430 events interface. Those events can be inserted wherever uprobes 431 can probe, and record various registers. 432 This option is required if you plan to use perf-probe subcommand 433 of perf tools on user space applications. 434 435config PROBE_EVENTS 436 def_bool n 437 438config DYNAMIC_FTRACE 439 bool "enable/disable function tracing dynamically" 440 depends on FUNCTION_TRACER 441 depends on HAVE_DYNAMIC_FTRACE 442 default y 443 help 444 This option will modify all the calls to function tracing 445 dynamically (will patch them out of the binary image and 446 replace them with a No-Op instruction) on boot up. During 447 compile time, a table is made of all the locations that ftrace 448 can function trace, and this table is linked into the kernel 449 image. When this is enabled, functions can be individually 450 enabled, and the functions not enabled will not affect 451 performance of the system. 452 453 See the files in /sys/kernel/debug/tracing: 454 available_filter_functions 455 set_ftrace_filter 456 set_ftrace_notrace 457 458 This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but 459 otherwise has native performance as long as no tracing is active. 460 461config DYNAMIC_FTRACE_WITH_REGS 462 def_bool y 463 depends on DYNAMIC_FTRACE 464 depends on HAVE_DYNAMIC_FTRACE_WITH_REGS 465 466config FUNCTION_PROFILER 467 bool "Kernel function profiler" 468 depends on FUNCTION_TRACER 469 default n 470 help 471 This option enables the kernel function profiler. A file is created 472 in debugfs called function_profile_enabled which defaults to zero. 473 When a 1 is echoed into this file profiling begins, and when a 474 zero is entered, profiling stops. A "functions" file is created in 475 the trace_stats directory; this file shows the list of functions that 476 have been hit and their counters. 477 478 If in doubt, say N. 479 480config FTRACE_MCOUNT_RECORD 481 def_bool y 482 depends on DYNAMIC_FTRACE 483 depends on HAVE_FTRACE_MCOUNT_RECORD 484 485config FTRACE_SELFTEST 486 bool 487 488config FTRACE_STARTUP_TEST 489 bool "Perform a startup test on ftrace" 490 depends on GENERIC_TRACER 491 select FTRACE_SELFTEST 492 help 493 This option performs a series of startup tests on ftrace. On bootup 494 a series of tests are made to verify that the tracer is 495 functioning properly. It will do tests on all the configured 496 tracers of ftrace. 497 498config EVENT_TRACE_TEST_SYSCALLS 499 bool "Run selftest on syscall events" 500 depends on FTRACE_STARTUP_TEST 501 help 502 This option will also enable testing every syscall event. 503 It only enables the event and disables it and runs various loads 504 with the event enabled. This adds a bit more time for kernel boot 505 up since it runs this on every system call defined. 506 507 TBD - enable a way to actually call the syscalls as we test their 508 events 509 510config MMIOTRACE 511 bool "Memory mapped IO tracing" 512 depends on HAVE_MMIOTRACE_SUPPORT && PCI 513 select GENERIC_TRACER 514 help 515 Mmiotrace traces Memory Mapped I/O access and is meant for 516 debugging and reverse engineering. It is called from the ioremap 517 implementation and works via page faults. Tracing is disabled by 518 default and can be enabled at run-time. 519 520 See Documentation/trace/mmiotrace.txt. 521 If you are not helping to develop drivers, say N. 522 523config MMIOTRACE_TEST 524 tristate "Test module for mmiotrace" 525 depends on MMIOTRACE && m 526 help 527 This is a dumb module for testing mmiotrace. It is very dangerous 528 as it will write garbage to IO memory starting at a given address. 529 However, it should be safe to use on e.g. unused portion of VRAM. 530 531 Say N, unless you absolutely know what you are doing. 532 533config TRACEPOINT_BENCHMARK 534 bool "Add tracepoint that benchmarks tracepoints" 535 help 536 This option creates the tracepoint "benchmark:benchmark_event". 537 When the tracepoint is enabled, it kicks off a kernel thread that 538 goes into an infinite loop (calling cond_sched() to let other tasks 539 run), and calls the tracepoint. Each iteration will record the time 540 it took to write to the tracepoint and the next iteration that 541 data will be passed to the tracepoint itself. That is, the tracepoint 542 will report the time it took to do the previous tracepoint. 543 The string written to the tracepoint is a static string of 128 bytes 544 to keep the time the same. The initial string is simply a write of 545 "START". The second string records the cold cache time of the first 546 write which is not added to the rest of the calculations. 547 548 As it is a tight loop, it benchmarks as hot cache. That's fine because 549 we care most about hot paths that are probably in cache already. 550 551 An example of the output: 552 553 START 554 first=3672 [COLD CACHED] 555 last=632 first=3672 max=632 min=632 avg=316 std=446 std^2=199712 556 last=278 first=3672 max=632 min=278 avg=303 std=316 std^2=100337 557 last=277 first=3672 max=632 min=277 avg=296 std=258 std^2=67064 558 last=273 first=3672 max=632 min=273 avg=292 std=224 std^2=50411 559 last=273 first=3672 max=632 min=273 avg=288 std=200 std^2=40389 560 last=281 first=3672 max=632 min=273 avg=287 std=183 std^2=33666 561 562 563config RING_BUFFER_BENCHMARK 564 tristate "Ring buffer benchmark stress tester" 565 depends on RING_BUFFER 566 help 567 This option creates a test to stress the ring buffer and benchmark it. 568 It creates its own ring buffer such that it will not interfere with 569 any other users of the ring buffer (such as ftrace). It then creates 570 a producer and consumer that will run for 10 seconds and sleep for 571 10 seconds. Each interval it will print out the number of events 572 it recorded and give a rough estimate of how long each iteration took. 573 574 It does not disable interrupts or raise its priority, so it may be 575 affected by processes that are running. 576 577 If unsure, say N. 578 579config RING_BUFFER_STARTUP_TEST 580 bool "Ring buffer startup self test" 581 depends on RING_BUFFER 582 help 583 Run a simple self test on the ring buffer on boot up. Late in the 584 kernel boot sequence, the test will start that kicks off 585 a thread per cpu. Each thread will write various size events 586 into the ring buffer. Another thread is created to send IPIs 587 to each of the threads, where the IPI handler will also write 588 to the ring buffer, to test/stress the nesting ability. 589 If any anomalies are discovered, a warning will be displayed 590 and all ring buffers will be disabled. 591 592 The test runs for 10 seconds. This will slow your boot time 593 by at least 10 more seconds. 594 595 At the end of the test, statics and more checks are done. 596 It will output the stats of each per cpu buffer. What 597 was written, the sizes, what was read, what was lost, and 598 other similar details. 599 600 If unsure, say N 601 602endif # FTRACE 603 604endif # TRACING_SUPPORT 605 606