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 select GLOB 74 bool 75 76config CONTEXT_SWITCH_TRACER 77 bool 78 79config RING_BUFFER_ALLOW_SWAP 80 bool 81 help 82 Allow the use of ring_buffer_swap_cpu. 83 Adds a very slight overhead to tracing when enabled. 84 85# All tracer options should select GENERIC_TRACER. For those options that are 86# enabled by all tracers (context switch and event tracer) they select TRACING. 87# This allows those options to appear when no other tracer is selected. But the 88# options do not appear when something else selects it. We need the two options 89# GENERIC_TRACER and TRACING to avoid circular dependencies to accomplish the 90# hiding of the automatic options. 91 92config TRACING 93 bool 94 select DEBUG_FS 95 select RING_BUFFER 96 select STACKTRACE if STACKTRACE_SUPPORT 97 select TRACEPOINTS 98 select NOP_TRACER 99 select BINARY_PRINTF 100 select EVENT_TRACING 101 select TRACE_CLOCK 102 103config GENERIC_TRACER 104 bool 105 select TRACING 106 107# 108# Minimum requirements an architecture has to meet for us to 109# be able to offer generic tracing facilities: 110# 111config TRACING_SUPPORT 112 bool 113 # PPC32 has no irqflags tracing support, but it can use most of the 114 # tracers anyway, they were tested to build and work. Note that new 115 # exceptions to this list aren't welcomed, better implement the 116 # irqflags tracing for your architecture. 117 depends on TRACE_IRQFLAGS_SUPPORT || PPC32 118 depends on STACKTRACE_SUPPORT 119 default y 120 121if TRACING_SUPPORT 122 123menuconfig FTRACE 124 bool "Tracers" 125 default y if DEBUG_KERNEL 126 help 127 Enable the kernel tracing infrastructure. 128 129if FTRACE 130 131config FUNCTION_TRACER 132 bool "Kernel Function Tracer" 133 depends on HAVE_FUNCTION_TRACER 134 select KALLSYMS 135 select GENERIC_TRACER 136 select CONTEXT_SWITCH_TRACER 137 select GLOB 138 help 139 Enable the kernel to trace every kernel function. This is done 140 by using a compiler feature to insert a small, 5-byte No-Operation 141 instruction at the beginning of every kernel function, which NOP 142 sequence is then dynamically patched into a tracer call when 143 tracing is enabled by the administrator. If it's runtime disabled 144 (the bootup default), then the overhead of the instructions is very 145 small and not measurable even in micro-benchmarks. 146 147config FUNCTION_GRAPH_TRACER 148 bool "Kernel Function Graph Tracer" 149 depends on HAVE_FUNCTION_GRAPH_TRACER 150 depends on FUNCTION_TRACER 151 depends on !X86_32 || !CC_OPTIMIZE_FOR_SIZE 152 default y 153 help 154 Enable the kernel to trace a function at both its return 155 and its entry. 156 Its first purpose is to trace the duration of functions and 157 draw a call graph for each thread with some information like 158 the return value. This is done by setting the current return 159 address on the current task structure into a stack of calls. 160 161 162config IRQSOFF_TRACER 163 bool "Interrupts-off Latency Tracer" 164 default n 165 depends on TRACE_IRQFLAGS_SUPPORT 166 depends on !ARCH_USES_GETTIMEOFFSET 167 select TRACE_IRQFLAGS 168 select GENERIC_TRACER 169 select TRACER_MAX_TRACE 170 select RING_BUFFER_ALLOW_SWAP 171 select TRACER_SNAPSHOT 172 select TRACER_SNAPSHOT_PER_CPU_SWAP 173 help 174 This option measures the time spent in irqs-off critical 175 sections, with microsecond accuracy. 176 177 The default measurement method is a maximum search, which is 178 disabled by default and can be runtime (re-)started 179 via: 180 181 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency 182 183 (Note that kernel size and overhead increase with this option 184 enabled. This option and the preempt-off timing option can be 185 used together or separately.) 186 187config PREEMPT_TRACER 188 bool "Preemption-off Latency Tracer" 189 default n 190 depends on !ARCH_USES_GETTIMEOFFSET 191 depends on PREEMPT 192 select GENERIC_TRACER 193 select TRACER_MAX_TRACE 194 select RING_BUFFER_ALLOW_SWAP 195 select TRACER_SNAPSHOT 196 select TRACER_SNAPSHOT_PER_CPU_SWAP 197 help 198 This option measures the time spent in preemption-off critical 199 sections, with microsecond accuracy. 200 201 The default measurement method is a maximum search, which is 202 disabled by default and can be runtime (re-)started 203 via: 204 205 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency 206 207 (Note that kernel size and overhead increase with this option 208 enabled. This option and the irqs-off timing option can be 209 used together or separately.) 210 211config SCHED_TRACER 212 bool "Scheduling Latency Tracer" 213 select GENERIC_TRACER 214 select CONTEXT_SWITCH_TRACER 215 select TRACER_MAX_TRACE 216 select TRACER_SNAPSHOT 217 help 218 This tracer tracks the latency of the highest priority task 219 to be scheduled in, starting from the point it has woken up. 220 221config HWLAT_TRACER 222 bool "Tracer to detect hardware latencies (like SMIs)" 223 select GENERIC_TRACER 224 help 225 This tracer, when enabled will create one or more kernel threads, 226 depening on what the cpumask file is set to, which each thread 227 spinning in a loop looking for interruptions caused by 228 something other than the kernel. For example, if a 229 System Management Interrupt (SMI) takes a noticeable amount of 230 time, this tracer will detect it. This is useful for testing 231 if a system is reliable for Real Time tasks. 232 233 Some files are created in the tracing directory when this 234 is enabled: 235 236 hwlat_detector/width - time in usecs for how long to spin for 237 hwlat_detector/window - time in usecs between the start of each 238 iteration 239 240 A kernel thread is created that will spin with interrupts disabled 241 for "width" microseconds in every "widow" cycle. It will not spin 242 for "window - width" microseconds, where the system can 243 continue to operate. 244 245 The output will appear in the trace and trace_pipe files. 246 247 When the tracer is not running, it has no affect on the system, 248 but when it is running, it can cause the system to be 249 periodically non responsive. Do not run this tracer on a 250 production system. 251 252 To enable this tracer, echo in "hwlat" into the current_tracer 253 file. Every time a latency is greater than tracing_thresh, it will 254 be recorded into the ring buffer. 255 256config ENABLE_DEFAULT_TRACERS 257 bool "Trace process context switches and events" 258 depends on !GENERIC_TRACER 259 select TRACING 260 help 261 This tracer hooks to various trace points in the kernel, 262 allowing the user to pick and choose which trace point they 263 want to trace. It also includes the sched_switch tracer plugin. 264 265config FTRACE_SYSCALLS 266 bool "Trace syscalls" 267 depends on HAVE_SYSCALL_TRACEPOINTS 268 select GENERIC_TRACER 269 select KALLSYMS 270 help 271 Basic tracer to catch the syscall entry and exit events. 272 273config TRACER_SNAPSHOT 274 bool "Create a snapshot trace buffer" 275 select TRACER_MAX_TRACE 276 help 277 Allow tracing users to take snapshot of the current buffer using the 278 ftrace interface, e.g.: 279 280 echo 1 > /sys/kernel/debug/tracing/snapshot 281 cat snapshot 282 283config TRACER_SNAPSHOT_PER_CPU_SWAP 284 bool "Allow snapshot to swap per CPU" 285 depends on TRACER_SNAPSHOT 286 select RING_BUFFER_ALLOW_SWAP 287 help 288 Allow doing a snapshot of a single CPU buffer instead of a 289 full swap (all buffers). If this is set, then the following is 290 allowed: 291 292 echo 1 > /sys/kernel/debug/tracing/per_cpu/cpu2/snapshot 293 294 After which, only the tracing buffer for CPU 2 was swapped with 295 the main tracing buffer, and the other CPU buffers remain the same. 296 297 When this is enabled, this adds a little more overhead to the 298 trace recording, as it needs to add some checks to synchronize 299 recording with swaps. But this does not affect the performance 300 of the overall system. This is enabled by default when the preempt 301 or irq latency tracers are enabled, as those need to swap as well 302 and already adds the overhead (plus a lot more). 303 304config TRACE_BRANCH_PROFILING 305 bool 306 select GENERIC_TRACER 307 308choice 309 prompt "Branch Profiling" 310 default BRANCH_PROFILE_NONE 311 help 312 The branch profiling is a software profiler. It will add hooks 313 into the C conditionals to test which path a branch takes. 314 315 The likely/unlikely profiler only looks at the conditions that 316 are annotated with a likely or unlikely macro. 317 318 The "all branch" profiler will profile every if-statement in the 319 kernel. This profiler will also enable the likely/unlikely 320 profiler. 321 322 Either of the above profilers adds a bit of overhead to the system. 323 If unsure, choose "No branch profiling". 324 325config BRANCH_PROFILE_NONE 326 bool "No branch profiling" 327 help 328 No branch profiling. Branch profiling adds a bit of overhead. 329 Only enable it if you want to analyse the branching behavior. 330 Otherwise keep it disabled. 331 332config PROFILE_ANNOTATED_BRANCHES 333 bool "Trace likely/unlikely profiler" 334 select TRACE_BRANCH_PROFILING 335 help 336 This tracer profiles all likely and unlikely macros 337 in the kernel. It will display the results in: 338 339 /sys/kernel/debug/tracing/trace_stat/branch_annotated 340 341 Note: this will add a significant overhead; only turn this 342 on if you need to profile the system's use of these macros. 343 344config PROFILE_ALL_BRANCHES 345 bool "Profile all if conditionals" 346 select TRACE_BRANCH_PROFILING 347 help 348 This tracer profiles all branch conditions. Every if () 349 taken in the kernel is recorded whether it hit or miss. 350 The results will be displayed in: 351 352 /sys/kernel/debug/tracing/trace_stat/branch_all 353 354 This option also enables the likely/unlikely profiler. 355 356 This configuration, when enabled, will impose a great overhead 357 on the system. This should only be enabled when the system 358 is to be analyzed in much detail. 359endchoice 360 361config TRACING_BRANCHES 362 bool 363 help 364 Selected by tracers that will trace the likely and unlikely 365 conditions. This prevents the tracers themselves from being 366 profiled. Profiling the tracing infrastructure can only happen 367 when the likelys and unlikelys are not being traced. 368 369config BRANCH_TRACER 370 bool "Trace likely/unlikely instances" 371 depends on TRACE_BRANCH_PROFILING 372 select TRACING_BRANCHES 373 help 374 This traces the events of likely and unlikely condition 375 calls in the kernel. The difference between this and the 376 "Trace likely/unlikely profiler" is that this is not a 377 histogram of the callers, but actually places the calling 378 events into a running trace buffer to see when and where the 379 events happened, as well as their results. 380 381 Say N if unsure. 382 383config STACK_TRACER 384 bool "Trace max stack" 385 depends on HAVE_FUNCTION_TRACER 386 select FUNCTION_TRACER 387 select STACKTRACE 388 select KALLSYMS 389 help 390 This special tracer records the maximum stack footprint of the 391 kernel and displays it in /sys/kernel/debug/tracing/stack_trace. 392 393 This tracer works by hooking into every function call that the 394 kernel executes, and keeping a maximum stack depth value and 395 stack-trace saved. If this is configured with DYNAMIC_FTRACE 396 then it will not have any overhead while the stack tracer 397 is disabled. 398 399 To enable the stack tracer on bootup, pass in 'stacktrace' 400 on the kernel command line. 401 402 The stack tracer can also be enabled or disabled via the 403 sysctl kernel.stack_tracer_enabled 404 405 Say N if unsure. 406 407config BLK_DEV_IO_TRACE 408 bool "Support for tracing block IO actions" 409 depends on SYSFS 410 depends on BLOCK 411 select RELAY 412 select DEBUG_FS 413 select TRACEPOINTS 414 select GENERIC_TRACER 415 select STACKTRACE 416 help 417 Say Y here if you want to be able to trace the block layer actions 418 on a given queue. Tracing allows you to see any traffic happening 419 on a block device queue. For more information (and the userspace 420 support tools needed), fetch the blktrace tools from: 421 422 git://git.kernel.dk/blktrace.git 423 424 Tracing also is possible using the ftrace interface, e.g.: 425 426 echo 1 > /sys/block/sda/sda1/trace/enable 427 echo blk > /sys/kernel/debug/tracing/current_tracer 428 cat /sys/kernel/debug/tracing/trace_pipe 429 430 If unsure, say N. 431 432config KPROBE_EVENT 433 depends on KPROBES 434 depends on HAVE_REGS_AND_STACK_ACCESS_API 435 bool "Enable kprobes-based dynamic events" 436 select TRACING 437 select PROBE_EVENTS 438 default y 439 help 440 This allows the user to add tracing events (similar to tracepoints) 441 on the fly via the ftrace interface. See 442 Documentation/trace/kprobetrace.txt for more details. 443 444 Those events can be inserted wherever kprobes can probe, and record 445 various register and memory values. 446 447 This option is also required by perf-probe subcommand of perf tools. 448 If you want to use perf tools, this option is strongly recommended. 449 450config UPROBE_EVENT 451 bool "Enable uprobes-based dynamic events" 452 depends on ARCH_SUPPORTS_UPROBES 453 depends on MMU 454 depends on PERF_EVENTS 455 select UPROBES 456 select PROBE_EVENTS 457 select TRACING 458 default n 459 help 460 This allows the user to add tracing events on top of userspace 461 dynamic events (similar to tracepoints) on the fly via the trace 462 events interface. Those events can be inserted wherever uprobes 463 can probe, and record various registers. 464 This option is required if you plan to use perf-probe subcommand 465 of perf tools on user space applications. 466 467config BPF_EVENTS 468 depends on BPF_SYSCALL 469 depends on (KPROBE_EVENT || UPROBE_EVENT) && PERF_EVENTS 470 bool 471 default y 472 help 473 This allows the user to attach BPF programs to kprobe events. 474 475config PROBE_EVENTS 476 def_bool n 477 478config DYNAMIC_FTRACE 479 bool "enable/disable function tracing dynamically" 480 depends on FUNCTION_TRACER 481 depends on HAVE_DYNAMIC_FTRACE 482 default y 483 help 484 This option will modify all the calls to function tracing 485 dynamically (will patch them out of the binary image and 486 replace them with a No-Op instruction) on boot up. During 487 compile time, a table is made of all the locations that ftrace 488 can function trace, and this table is linked into the kernel 489 image. When this is enabled, functions can be individually 490 enabled, and the functions not enabled will not affect 491 performance of the system. 492 493 See the files in /sys/kernel/debug/tracing: 494 available_filter_functions 495 set_ftrace_filter 496 set_ftrace_notrace 497 498 This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but 499 otherwise has native performance as long as no tracing is active. 500 501config DYNAMIC_FTRACE_WITH_REGS 502 def_bool y 503 depends on DYNAMIC_FTRACE 504 depends on HAVE_DYNAMIC_FTRACE_WITH_REGS 505 506config FUNCTION_PROFILER 507 bool "Kernel function profiler" 508 depends on FUNCTION_TRACER 509 default n 510 help 511 This option enables the kernel function profiler. A file is created 512 in debugfs called function_profile_enabled which defaults to zero. 513 When a 1 is echoed into this file profiling begins, and when a 514 zero is entered, profiling stops. A "functions" file is created in 515 the trace_stats directory; this file shows the list of functions that 516 have been hit and their counters. 517 518 If in doubt, say N. 519 520config FTRACE_MCOUNT_RECORD 521 def_bool y 522 depends on DYNAMIC_FTRACE 523 depends on HAVE_FTRACE_MCOUNT_RECORD 524 525config FTRACE_SELFTEST 526 bool 527 528config FTRACE_STARTUP_TEST 529 bool "Perform a startup test on ftrace" 530 depends on GENERIC_TRACER 531 select FTRACE_SELFTEST 532 help 533 This option performs a series of startup tests on ftrace. On bootup 534 a series of tests are made to verify that the tracer is 535 functioning properly. It will do tests on all the configured 536 tracers of ftrace. 537 538config EVENT_TRACE_TEST_SYSCALLS 539 bool "Run selftest on syscall events" 540 depends on FTRACE_STARTUP_TEST 541 help 542 This option will also enable testing every syscall event. 543 It only enables the event and disables it and runs various loads 544 with the event enabled. This adds a bit more time for kernel boot 545 up since it runs this on every system call defined. 546 547 TBD - enable a way to actually call the syscalls as we test their 548 events 549 550config MMIOTRACE 551 bool "Memory mapped IO tracing" 552 depends on HAVE_MMIOTRACE_SUPPORT && PCI 553 select GENERIC_TRACER 554 help 555 Mmiotrace traces Memory Mapped I/O access and is meant for 556 debugging and reverse engineering. It is called from the ioremap 557 implementation and works via page faults. Tracing is disabled by 558 default and can be enabled at run-time. 559 560 See Documentation/trace/mmiotrace.txt. 561 If you are not helping to develop drivers, say N. 562 563config TRACING_MAP 564 bool 565 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG 566 help 567 tracing_map is a special-purpose lock-free map for tracing, 568 separated out as a stand-alone facility in order to allow it 569 to be shared between multiple tracers. It isn't meant to be 570 generally used outside of that context, and is normally 571 selected by tracers that use it. 572 573config HIST_TRIGGERS 574 bool "Histogram triggers" 575 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG 576 select TRACING_MAP 577 select TRACING 578 default n 579 help 580 Hist triggers allow one or more arbitrary trace event fields 581 to be aggregated into hash tables and dumped to stdout by 582 reading a debugfs/tracefs file. They're useful for 583 gathering quick and dirty (though precise) summaries of 584 event activity as an initial guide for further investigation 585 using more advanced tools. 586 587 See Documentation/trace/events.txt. 588 If in doubt, say N. 589 590config MMIOTRACE_TEST 591 tristate "Test module for mmiotrace" 592 depends on MMIOTRACE && m 593 help 594 This is a dumb module for testing mmiotrace. It is very dangerous 595 as it will write garbage to IO memory starting at a given address. 596 However, it should be safe to use on e.g. unused portion of VRAM. 597 598 Say N, unless you absolutely know what you are doing. 599 600config TRACEPOINT_BENCHMARK 601 bool "Add tracepoint that benchmarks tracepoints" 602 help 603 This option creates the tracepoint "benchmark:benchmark_event". 604 When the tracepoint is enabled, it kicks off a kernel thread that 605 goes into an infinite loop (calling cond_sched() to let other tasks 606 run), and calls the tracepoint. Each iteration will record the time 607 it took to write to the tracepoint and the next iteration that 608 data will be passed to the tracepoint itself. That is, the tracepoint 609 will report the time it took to do the previous tracepoint. 610 The string written to the tracepoint is a static string of 128 bytes 611 to keep the time the same. The initial string is simply a write of 612 "START". The second string records the cold cache time of the first 613 write which is not added to the rest of the calculations. 614 615 As it is a tight loop, it benchmarks as hot cache. That's fine because 616 we care most about hot paths that are probably in cache already. 617 618 An example of the output: 619 620 START 621 first=3672 [COLD CACHED] 622 last=632 first=3672 max=632 min=632 avg=316 std=446 std^2=199712 623 last=278 first=3672 max=632 min=278 avg=303 std=316 std^2=100337 624 last=277 first=3672 max=632 min=277 avg=296 std=258 std^2=67064 625 last=273 first=3672 max=632 min=273 avg=292 std=224 std^2=50411 626 last=273 first=3672 max=632 min=273 avg=288 std=200 std^2=40389 627 last=281 first=3672 max=632 min=273 avg=287 std=183 std^2=33666 628 629 630config RING_BUFFER_BENCHMARK 631 tristate "Ring buffer benchmark stress tester" 632 depends on RING_BUFFER 633 help 634 This option creates a test to stress the ring buffer and benchmark it. 635 It creates its own ring buffer such that it will not interfere with 636 any other users of the ring buffer (such as ftrace). It then creates 637 a producer and consumer that will run for 10 seconds and sleep for 638 10 seconds. Each interval it will print out the number of events 639 it recorded and give a rough estimate of how long each iteration took. 640 641 It does not disable interrupts or raise its priority, so it may be 642 affected by processes that are running. 643 644 If unsure, say N. 645 646config RING_BUFFER_STARTUP_TEST 647 bool "Ring buffer startup self test" 648 depends on RING_BUFFER 649 help 650 Run a simple self test on the ring buffer on boot up. Late in the 651 kernel boot sequence, the test will start that kicks off 652 a thread per cpu. Each thread will write various size events 653 into the ring buffer. Another thread is created to send IPIs 654 to each of the threads, where the IPI handler will also write 655 to the ring buffer, to test/stress the nesting ability. 656 If any anomalies are discovered, a warning will be displayed 657 and all ring buffers will be disabled. 658 659 The test runs for 10 seconds. This will slow your boot time 660 by at least 10 more seconds. 661 662 At the end of the test, statics and more checks are done. 663 It will output the stats of each per cpu buffer. What 664 was written, the sizes, what was read, what was lost, and 665 other similar details. 666 667 If unsure, say N 668 669config TRACE_ENUM_MAP_FILE 670 bool "Show enum mappings for trace events" 671 depends on TRACING 672 help 673 The "print fmt" of the trace events will show the enum names instead 674 of their values. This can cause problems for user space tools that 675 use this string to parse the raw data as user space does not know 676 how to convert the string to its value. 677 678 To fix this, there's a special macro in the kernel that can be used 679 to convert the enum into its value. If this macro is used, then the 680 print fmt strings will have the enums converted to their values. 681 682 If something does not get converted properly, this option can be 683 used to show what enums the kernel tried to convert. 684 685 This option is for debugging the enum conversions. A file is created 686 in the tracing directory called "enum_map" that will show the enum 687 names matched with their values and what trace event system they 688 belong too. 689 690 Normally, the mapping of the strings to values will be freed after 691 boot up or module load. With this option, they will not be freed, as 692 they are needed for the "enum_map" file. Enabling this option will 693 increase the memory footprint of the running kernel. 694 695 If unsure, say N 696 697config TRACING_EVENTS_GPIO 698 bool "Trace gpio events" 699 depends on GPIOLIB 700 default y 701 help 702 Enable tracing events for gpio subsystem 703 704endif # FTRACE 705 706endif # TRACING_SUPPORT 707 708