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_DYNAMIC_FTRACE 28 bool 29 help 30 See Documentation/trace/ftrace-design.txt 31 32config HAVE_DYNAMIC_FTRACE_WITH_REGS 33 bool 34 35config HAVE_FTRACE_MCOUNT_RECORD 36 bool 37 help 38 See Documentation/trace/ftrace-design.txt 39 40config HAVE_SYSCALL_TRACEPOINTS 41 bool 42 help 43 See Documentation/trace/ftrace-design.txt 44 45config HAVE_FENTRY 46 bool 47 help 48 Arch supports the gcc options -pg with -mfentry 49 50config HAVE_C_RECORDMCOUNT 51 bool 52 help 53 C version of recordmcount available? 54 55config TRACER_MAX_TRACE 56 bool 57 58config TRACE_CLOCK 59 bool 60 61config RING_BUFFER 62 bool 63 select TRACE_CLOCK 64 select IRQ_WORK 65 66config FTRACE_NMI_ENTER 67 bool 68 depends on HAVE_FTRACE_NMI_ENTER 69 default y 70 71config EVENT_TRACING 72 select CONTEXT_SWITCH_TRACER 73 bool 74 75config CONTEXT_SWITCH_TRACER 76 bool 77 78config RING_BUFFER_ALLOW_SWAP 79 bool 80 help 81 Allow the use of ring_buffer_swap_cpu. 82 Adds a very slight overhead to tracing when enabled. 83 84# All tracer options should select GENERIC_TRACER. For those options that are 85# enabled by all tracers (context switch and event tracer) they select TRACING. 86# This allows those options to appear when no other tracer is selected. But the 87# options do not appear when something else selects it. We need the two options 88# GENERIC_TRACER and TRACING to avoid circular dependencies to accomplish the 89# hiding of the automatic options. 90 91config TRACING 92 bool 93 select DEBUG_FS 94 select RING_BUFFER 95 select STACKTRACE if STACKTRACE_SUPPORT 96 select TRACEPOINTS 97 select NOP_TRACER 98 select BINARY_PRINTF 99 select EVENT_TRACING 100 select TRACE_CLOCK 101 102config GENERIC_TRACER 103 bool 104 select TRACING 105 106# 107# Minimum requirements an architecture has to meet for us to 108# be able to offer generic tracing facilities: 109# 110config TRACING_SUPPORT 111 bool 112 # PPC32 has no irqflags tracing support, but it can use most of the 113 # tracers anyway, they were tested to build and work. Note that new 114 # exceptions to this list aren't welcomed, better implement the 115 # irqflags tracing for your architecture. 116 depends on TRACE_IRQFLAGS_SUPPORT || PPC32 117 depends on STACKTRACE_SUPPORT 118 default y 119 120if TRACING_SUPPORT 121 122menuconfig FTRACE 123 bool "Tracers" 124 default y if DEBUG_KERNEL 125 help 126 Enable the kernel tracing infrastructure. 127 128if FTRACE 129 130config FUNCTION_TRACER 131 bool "Kernel Function Tracer" 132 depends on HAVE_FUNCTION_TRACER 133 select KALLSYMS 134 select GENERIC_TRACER 135 select CONTEXT_SWITCH_TRACER 136 help 137 Enable the kernel to trace every kernel function. This is done 138 by using a compiler feature to insert a small, 5-byte No-Operation 139 instruction at the beginning of every kernel function, which NOP 140 sequence is then dynamically patched into a tracer call when 141 tracing is enabled by the administrator. If it's runtime disabled 142 (the bootup default), then the overhead of the instructions is very 143 small and not measurable even in micro-benchmarks. 144 145config FUNCTION_GRAPH_TRACER 146 bool "Kernel Function Graph Tracer" 147 depends on HAVE_FUNCTION_GRAPH_TRACER 148 depends on FUNCTION_TRACER 149 depends on !X86_32 || !CC_OPTIMIZE_FOR_SIZE 150 default y 151 help 152 Enable the kernel to trace a function at both its return 153 and its entry. 154 Its first purpose is to trace the duration of functions and 155 draw a call graph for each thread with some information like 156 the return value. This is done by setting the current return 157 address on the current task structure into a stack of calls. 158 159 160config IRQSOFF_TRACER 161 bool "Interrupts-off Latency Tracer" 162 default n 163 depends on TRACE_IRQFLAGS_SUPPORT 164 depends on !ARCH_USES_GETTIMEOFFSET 165 select TRACE_IRQFLAGS 166 select GENERIC_TRACER 167 select TRACER_MAX_TRACE 168 select RING_BUFFER_ALLOW_SWAP 169 select TRACER_SNAPSHOT 170 select TRACER_SNAPSHOT_PER_CPU_SWAP 171 help 172 This option measures the time spent in irqs-off critical 173 sections, with microsecond accuracy. 174 175 The default measurement method is a maximum search, which is 176 disabled by default and can be runtime (re-)started 177 via: 178 179 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency 180 181 (Note that kernel size and overhead increase with this option 182 enabled. This option and the preempt-off timing option can be 183 used together or separately.) 184 185config PREEMPT_TRACER 186 bool "Preemption-off Latency Tracer" 187 default n 188 depends on !ARCH_USES_GETTIMEOFFSET 189 depends on PREEMPT 190 select GENERIC_TRACER 191 select TRACER_MAX_TRACE 192 select RING_BUFFER_ALLOW_SWAP 193 select TRACER_SNAPSHOT 194 select TRACER_SNAPSHOT_PER_CPU_SWAP 195 help 196 This option measures the time spent in preemption-off critical 197 sections, with microsecond accuracy. 198 199 The default measurement method is a maximum search, which is 200 disabled by default and can be runtime (re-)started 201 via: 202 203 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency 204 205 (Note that kernel size and overhead increase with this option 206 enabled. This option and the irqs-off timing option can be 207 used together or separately.) 208 209config SCHED_TRACER 210 bool "Scheduling Latency Tracer" 211 select GENERIC_TRACER 212 select CONTEXT_SWITCH_TRACER 213 select TRACER_MAX_TRACE 214 select TRACER_SNAPSHOT 215 help 216 This tracer tracks the latency of the highest priority task 217 to be scheduled in, starting from the point it has woken up. 218 219config ENABLE_DEFAULT_TRACERS 220 bool "Trace process context switches and events" 221 depends on !GENERIC_TRACER 222 select TRACING 223 help 224 This tracer hooks to various trace points in the kernel, 225 allowing the user to pick and choose which trace point they 226 want to trace. It also includes the sched_switch tracer plugin. 227 228config FTRACE_SYSCALLS 229 bool "Trace syscalls" 230 depends on HAVE_SYSCALL_TRACEPOINTS 231 select GENERIC_TRACER 232 select KALLSYMS 233 help 234 Basic tracer to catch the syscall entry and exit events. 235 236config TRACER_SNAPSHOT 237 bool "Create a snapshot trace buffer" 238 select TRACER_MAX_TRACE 239 help 240 Allow tracing users to take snapshot of the current buffer using the 241 ftrace interface, e.g.: 242 243 echo 1 > /sys/kernel/debug/tracing/snapshot 244 cat snapshot 245 246config TRACER_SNAPSHOT_PER_CPU_SWAP 247 bool "Allow snapshot to swap per CPU" 248 depends on TRACER_SNAPSHOT 249 select RING_BUFFER_ALLOW_SWAP 250 help 251 Allow doing a snapshot of a single CPU buffer instead of a 252 full swap (all buffers). If this is set, then the following is 253 allowed: 254 255 echo 1 > /sys/kernel/debug/tracing/per_cpu/cpu2/snapshot 256 257 After which, only the tracing buffer for CPU 2 was swapped with 258 the main tracing buffer, and the other CPU buffers remain the same. 259 260 When this is enabled, this adds a little more overhead to the 261 trace recording, as it needs to add some checks to synchronize 262 recording with swaps. But this does not affect the performance 263 of the overall system. This is enabled by default when the preempt 264 or irq latency tracers are enabled, as those need to swap as well 265 and already adds the overhead (plus a lot more). 266 267config TRACE_BRANCH_PROFILING 268 bool 269 select GENERIC_TRACER 270 271choice 272 prompt "Branch Profiling" 273 default BRANCH_PROFILE_NONE 274 help 275 The branch profiling is a software profiler. It will add hooks 276 into the C conditionals to test which path a branch takes. 277 278 The likely/unlikely profiler only looks at the conditions that 279 are annotated with a likely or unlikely macro. 280 281 The "all branch" profiler will profile every if-statement in the 282 kernel. This profiler will also enable the likely/unlikely 283 profiler. 284 285 Either of the above profilers adds a bit of overhead to the system. 286 If unsure, choose "No branch profiling". 287 288config BRANCH_PROFILE_NONE 289 bool "No branch profiling" 290 help 291 No branch profiling. Branch profiling adds a bit of overhead. 292 Only enable it if you want to analyse the branching behavior. 293 Otherwise keep it disabled. 294 295config PROFILE_ANNOTATED_BRANCHES 296 bool "Trace likely/unlikely profiler" 297 select TRACE_BRANCH_PROFILING 298 help 299 This tracer profiles all likely and unlikely macros 300 in the kernel. It will display the results in: 301 302 /sys/kernel/debug/tracing/trace_stat/branch_annotated 303 304 Note: this will add a significant overhead; only turn this 305 on if you need to profile the system's use of these macros. 306 307config PROFILE_ALL_BRANCHES 308 bool "Profile all if conditionals" 309 select TRACE_BRANCH_PROFILING 310 help 311 This tracer profiles all branch conditions. Every if () 312 taken in the kernel is recorded whether it hit or miss. 313 The results will be displayed in: 314 315 /sys/kernel/debug/tracing/trace_stat/branch_all 316 317 This option also enables the likely/unlikely profiler. 318 319 This configuration, when enabled, will impose a great overhead 320 on the system. This should only be enabled when the system 321 is to be analyzed in much detail. 322endchoice 323 324config TRACING_BRANCHES 325 bool 326 help 327 Selected by tracers that will trace the likely and unlikely 328 conditions. This prevents the tracers themselves from being 329 profiled. Profiling the tracing infrastructure can only happen 330 when the likelys and unlikelys are not being traced. 331 332config BRANCH_TRACER 333 bool "Trace likely/unlikely instances" 334 depends on TRACE_BRANCH_PROFILING 335 select TRACING_BRANCHES 336 help 337 This traces the events of likely and unlikely condition 338 calls in the kernel. The difference between this and the 339 "Trace likely/unlikely profiler" is that this is not a 340 histogram of the callers, but actually places the calling 341 events into a running trace buffer to see when and where the 342 events happened, as well as their results. 343 344 Say N if unsure. 345 346config STACK_TRACER 347 bool "Trace max stack" 348 depends on HAVE_FUNCTION_TRACER 349 select FUNCTION_TRACER 350 select STACKTRACE 351 select KALLSYMS 352 help 353 This special tracer records the maximum stack footprint of the 354 kernel and displays it in /sys/kernel/debug/tracing/stack_trace. 355 356 This tracer works by hooking into every function call that the 357 kernel executes, and keeping a maximum stack depth value and 358 stack-trace saved. If this is configured with DYNAMIC_FTRACE 359 then it will not have any overhead while the stack tracer 360 is disabled. 361 362 To enable the stack tracer on bootup, pass in 'stacktrace' 363 on the kernel command line. 364 365 The stack tracer can also be enabled or disabled via the 366 sysctl kernel.stack_tracer_enabled 367 368 Say N if unsure. 369 370config BLK_DEV_IO_TRACE 371 bool "Support for tracing block IO actions" 372 depends on SYSFS 373 depends on BLOCK 374 select RELAY 375 select DEBUG_FS 376 select TRACEPOINTS 377 select GENERIC_TRACER 378 select STACKTRACE 379 help 380 Say Y here if you want to be able to trace the block layer actions 381 on a given queue. Tracing allows you to see any traffic happening 382 on a block device queue. For more information (and the userspace 383 support tools needed), fetch the blktrace tools from: 384 385 git://git.kernel.dk/blktrace.git 386 387 Tracing also is possible using the ftrace interface, e.g.: 388 389 echo 1 > /sys/block/sda/sda1/trace/enable 390 echo blk > /sys/kernel/debug/tracing/current_tracer 391 cat /sys/kernel/debug/tracing/trace_pipe 392 393 If unsure, say N. 394 395config KPROBE_EVENT 396 depends on KPROBES 397 depends on HAVE_REGS_AND_STACK_ACCESS_API 398 bool "Enable kprobes-based dynamic events" 399 select TRACING 400 select PROBE_EVENTS 401 default y 402 help 403 This allows the user to add tracing events (similar to tracepoints) 404 on the fly via the ftrace interface. See 405 Documentation/trace/kprobetrace.txt for more details. 406 407 Those events can be inserted wherever kprobes can probe, and record 408 various register and memory values. 409 410 This option is also required by perf-probe subcommand of perf tools. 411 If you want to use perf tools, this option is strongly recommended. 412 413config UPROBE_EVENT 414 bool "Enable uprobes-based dynamic events" 415 depends on ARCH_SUPPORTS_UPROBES 416 depends on MMU 417 depends on PERF_EVENTS 418 select UPROBES 419 select PROBE_EVENTS 420 select TRACING 421 default n 422 help 423 This allows the user to add tracing events on top of userspace 424 dynamic events (similar to tracepoints) on the fly via the trace 425 events interface. Those events can be inserted wherever uprobes 426 can probe, and record various registers. 427 This option is required if you plan to use perf-probe subcommand 428 of perf tools on user space applications. 429 430config BPF_EVENTS 431 depends on BPF_SYSCALL 432 depends on (KPROBE_EVENT || UPROBE_EVENT) && PERF_EVENTS 433 bool 434 default y 435 help 436 This allows the user to attach BPF programs to kprobe events. 437 438config PROBE_EVENTS 439 def_bool n 440 441config DYNAMIC_FTRACE 442 bool "enable/disable function tracing dynamically" 443 depends on FUNCTION_TRACER 444 depends on HAVE_DYNAMIC_FTRACE 445 default y 446 help 447 This option will modify all the calls to function tracing 448 dynamically (will patch them out of the binary image and 449 replace them with a No-Op instruction) on boot up. During 450 compile time, a table is made of all the locations that ftrace 451 can function trace, and this table is linked into the kernel 452 image. When this is enabled, functions can be individually 453 enabled, and the functions not enabled will not affect 454 performance of the system. 455 456 See the files in /sys/kernel/debug/tracing: 457 available_filter_functions 458 set_ftrace_filter 459 set_ftrace_notrace 460 461 This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but 462 otherwise has native performance as long as no tracing is active. 463 464config DYNAMIC_FTRACE_WITH_REGS 465 def_bool y 466 depends on DYNAMIC_FTRACE 467 depends on HAVE_DYNAMIC_FTRACE_WITH_REGS 468 469config FUNCTION_PROFILER 470 bool "Kernel function profiler" 471 depends on FUNCTION_TRACER 472 default n 473 help 474 This option enables the kernel function profiler. A file is created 475 in debugfs called function_profile_enabled which defaults to zero. 476 When a 1 is echoed into this file profiling begins, and when a 477 zero is entered, profiling stops. A "functions" file is created in 478 the trace_stats directory; this file shows the list of functions that 479 have been hit and their counters. 480 481 If in doubt, say N. 482 483config FTRACE_MCOUNT_RECORD 484 def_bool y 485 depends on DYNAMIC_FTRACE 486 depends on HAVE_FTRACE_MCOUNT_RECORD 487 488config FTRACE_SELFTEST 489 bool 490 491config FTRACE_STARTUP_TEST 492 bool "Perform a startup test on ftrace" 493 depends on GENERIC_TRACER 494 select FTRACE_SELFTEST 495 help 496 This option performs a series of startup tests on ftrace. On bootup 497 a series of tests are made to verify that the tracer is 498 functioning properly. It will do tests on all the configured 499 tracers of ftrace. 500 501config EVENT_TRACE_TEST_SYSCALLS 502 bool "Run selftest on syscall events" 503 depends on FTRACE_STARTUP_TEST 504 help 505 This option will also enable testing every syscall event. 506 It only enables the event and disables it and runs various loads 507 with the event enabled. This adds a bit more time for kernel boot 508 up since it runs this on every system call defined. 509 510 TBD - enable a way to actually call the syscalls as we test their 511 events 512 513config MMIOTRACE 514 bool "Memory mapped IO tracing" 515 depends on HAVE_MMIOTRACE_SUPPORT && PCI 516 select GENERIC_TRACER 517 help 518 Mmiotrace traces Memory Mapped I/O access and is meant for 519 debugging and reverse engineering. It is called from the ioremap 520 implementation and works via page faults. Tracing is disabled by 521 default and can be enabled at run-time. 522 523 See Documentation/trace/mmiotrace.txt. 524 If you are not helping to develop drivers, say N. 525 526config TRACING_MAP 527 bool 528 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG 529 help 530 tracing_map is a special-purpose lock-free map for tracing, 531 separated out as a stand-alone facility in order to allow it 532 to be shared between multiple tracers. It isn't meant to be 533 generally used outside of that context, and is normally 534 selected by tracers that use it. 535 536config HIST_TRIGGERS 537 bool "Histogram triggers" 538 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG 539 select TRACING_MAP 540 select TRACING 541 default n 542 help 543 Hist triggers allow one or more arbitrary trace event fields 544 to be aggregated into hash tables and dumped to stdout by 545 reading a debugfs/tracefs file. They're useful for 546 gathering quick and dirty (though precise) summaries of 547 event activity as an initial guide for further investigation 548 using more advanced tools. 549 550 See Documentation/trace/events.txt. 551 If in doubt, say N. 552 553config MMIOTRACE_TEST 554 tristate "Test module for mmiotrace" 555 depends on MMIOTRACE && m 556 help 557 This is a dumb module for testing mmiotrace. It is very dangerous 558 as it will write garbage to IO memory starting at a given address. 559 However, it should be safe to use on e.g. unused portion of VRAM. 560 561 Say N, unless you absolutely know what you are doing. 562 563config TRACEPOINT_BENCHMARK 564 bool "Add tracepoint that benchmarks tracepoints" 565 help 566 This option creates the tracepoint "benchmark:benchmark_event". 567 When the tracepoint is enabled, it kicks off a kernel thread that 568 goes into an infinite loop (calling cond_sched() to let other tasks 569 run), and calls the tracepoint. Each iteration will record the time 570 it took to write to the tracepoint and the next iteration that 571 data will be passed to the tracepoint itself. That is, the tracepoint 572 will report the time it took to do the previous tracepoint. 573 The string written to the tracepoint is a static string of 128 bytes 574 to keep the time the same. The initial string is simply a write of 575 "START". The second string records the cold cache time of the first 576 write which is not added to the rest of the calculations. 577 578 As it is a tight loop, it benchmarks as hot cache. That's fine because 579 we care most about hot paths that are probably in cache already. 580 581 An example of the output: 582 583 START 584 first=3672 [COLD CACHED] 585 last=632 first=3672 max=632 min=632 avg=316 std=446 std^2=199712 586 last=278 first=3672 max=632 min=278 avg=303 std=316 std^2=100337 587 last=277 first=3672 max=632 min=277 avg=296 std=258 std^2=67064 588 last=273 first=3672 max=632 min=273 avg=292 std=224 std^2=50411 589 last=273 first=3672 max=632 min=273 avg=288 std=200 std^2=40389 590 last=281 first=3672 max=632 min=273 avg=287 std=183 std^2=33666 591 592 593config RING_BUFFER_BENCHMARK 594 tristate "Ring buffer benchmark stress tester" 595 depends on RING_BUFFER 596 help 597 This option creates a test to stress the ring buffer and benchmark it. 598 It creates its own ring buffer such that it will not interfere with 599 any other users of the ring buffer (such as ftrace). It then creates 600 a producer and consumer that will run for 10 seconds and sleep for 601 10 seconds. Each interval it will print out the number of events 602 it recorded and give a rough estimate of how long each iteration took. 603 604 It does not disable interrupts or raise its priority, so it may be 605 affected by processes that are running. 606 607 If unsure, say N. 608 609config RING_BUFFER_STARTUP_TEST 610 bool "Ring buffer startup self test" 611 depends on RING_BUFFER 612 help 613 Run a simple self test on the ring buffer on boot up. Late in the 614 kernel boot sequence, the test will start that kicks off 615 a thread per cpu. Each thread will write various size events 616 into the ring buffer. Another thread is created to send IPIs 617 to each of the threads, where the IPI handler will also write 618 to the ring buffer, to test/stress the nesting ability. 619 If any anomalies are discovered, a warning will be displayed 620 and all ring buffers will be disabled. 621 622 The test runs for 10 seconds. This will slow your boot time 623 by at least 10 more seconds. 624 625 At the end of the test, statics and more checks are done. 626 It will output the stats of each per cpu buffer. What 627 was written, the sizes, what was read, what was lost, and 628 other similar details. 629 630 If unsure, say N 631 632config TRACE_ENUM_MAP_FILE 633 bool "Show enum mappings for trace events" 634 depends on TRACING 635 help 636 The "print fmt" of the trace events will show the enum names instead 637 of their values. This can cause problems for user space tools that 638 use this string to parse the raw data as user space does not know 639 how to convert the string to its value. 640 641 To fix this, there's a special macro in the kernel that can be used 642 to convert the enum into its value. If this macro is used, then the 643 print fmt strings will have the enums converted to their values. 644 645 If something does not get converted properly, this option can be 646 used to show what enums the kernel tried to convert. 647 648 This option is for debugging the enum conversions. A file is created 649 in the tracing directory called "enum_map" that will show the enum 650 names matched with their values and what trace event system they 651 belong too. 652 653 Normally, the mapping of the strings to values will be freed after 654 boot up or module load. With this option, they will not be freed, as 655 they are needed for the "enum_map" file. Enabling this option will 656 increase the memory footprint of the running kernel. 657 658 If unsure, say N 659 660config TRACING_EVENTS_GPIO 661 bool "Trace gpio events" 662 depends on GPIOLIB 663 default y 664 help 665 Enable tracing events for gpio subsystem 666 667endif # FTRACE 668 669endif # TRACING_SUPPORT 670 671