1# SPDX-License-Identifier: GPL-2.0-only 2# 3# Architectures that offer an FUNCTION_TRACER implementation should 4# select HAVE_FUNCTION_TRACER: 5# 6 7config USER_STACKTRACE_SUPPORT 8 bool 9 10config NOP_TRACER 11 bool 12 13config HAVE_FTRACE_NMI_ENTER 14 bool 15 help 16 See Documentation/trace/ftrace-design.rst 17 18config HAVE_FUNCTION_TRACER 19 bool 20 help 21 See Documentation/trace/ftrace-design.rst 22 23config HAVE_FUNCTION_GRAPH_TRACER 24 bool 25 help 26 See Documentation/trace/ftrace-design.rst 27 28config HAVE_DYNAMIC_FTRACE 29 bool 30 help 31 See Documentation/trace/ftrace-design.rst 32 33config HAVE_DYNAMIC_FTRACE_WITH_REGS 34 bool 35 36config HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 37 bool 38 39config HAVE_FTRACE_MCOUNT_RECORD 40 bool 41 help 42 See Documentation/trace/ftrace-design.rst 43 44config HAVE_SYSCALL_TRACEPOINTS 45 bool 46 help 47 See Documentation/trace/ftrace-design.rst 48 49config HAVE_FENTRY 50 bool 51 help 52 Arch supports the gcc options -pg with -mfentry 53 54config HAVE_NOP_MCOUNT 55 bool 56 help 57 Arch supports the gcc options -pg with -mrecord-mcount and -nop-mcount 58 59config HAVE_C_RECORDMCOUNT 60 bool 61 help 62 C version of recordmcount available? 63 64config TRACER_MAX_TRACE 65 bool 66 67config TRACE_CLOCK 68 bool 69 70config RING_BUFFER 71 bool 72 select TRACE_CLOCK 73 select IRQ_WORK 74 75config FTRACE_NMI_ENTER 76 bool 77 depends on HAVE_FTRACE_NMI_ENTER 78 default y 79 80config EVENT_TRACING 81 select CONTEXT_SWITCH_TRACER 82 select GLOB 83 bool 84 85config CONTEXT_SWITCH_TRACER 86 bool 87 88config RING_BUFFER_ALLOW_SWAP 89 bool 90 help 91 Allow the use of ring_buffer_swap_cpu. 92 Adds a very slight overhead to tracing when enabled. 93 94config PREEMPTIRQ_TRACEPOINTS 95 bool 96 depends on TRACE_PREEMPT_TOGGLE || TRACE_IRQFLAGS 97 select TRACING 98 default y 99 help 100 Create preempt/irq toggle tracepoints if needed, so that other parts 101 of the kernel can use them to generate or add hooks to them. 102 103# All tracer options should select GENERIC_TRACER. For those options that are 104# enabled by all tracers (context switch and event tracer) they select TRACING. 105# This allows those options to appear when no other tracer is selected. But the 106# options do not appear when something else selects it. We need the two options 107# GENERIC_TRACER and TRACING to avoid circular dependencies to accomplish the 108# hiding of the automatic options. 109 110config TRACING 111 bool 112 select RING_BUFFER 113 select STACKTRACE if STACKTRACE_SUPPORT 114 select TRACEPOINTS 115 select NOP_TRACER 116 select BINARY_PRINTF 117 select EVENT_TRACING 118 select TRACE_CLOCK 119 120config GENERIC_TRACER 121 bool 122 select TRACING 123 124# 125# Minimum requirements an architecture has to meet for us to 126# be able to offer generic tracing facilities: 127# 128config TRACING_SUPPORT 129 bool 130 depends on TRACE_IRQFLAGS_SUPPORT 131 depends on STACKTRACE_SUPPORT 132 default y 133 134if TRACING_SUPPORT 135 136menuconfig FTRACE 137 bool "Tracers" 138 default y if DEBUG_KERNEL 139 help 140 Enable the kernel tracing infrastructure. 141 142if FTRACE 143 144config FUNCTION_TRACER 145 bool "Kernel Function Tracer" 146 depends on HAVE_FUNCTION_TRACER 147 select KALLSYMS 148 select GENERIC_TRACER 149 select CONTEXT_SWITCH_TRACER 150 select GLOB 151 select TASKS_RCU if PREEMPTION 152 help 153 Enable the kernel to trace every kernel function. This is done 154 by using a compiler feature to insert a small, 5-byte No-Operation 155 instruction at the beginning of every kernel function, which NOP 156 sequence is then dynamically patched into a tracer call when 157 tracing is enabled by the administrator. If it's runtime disabled 158 (the bootup default), then the overhead of the instructions is very 159 small and not measurable even in micro-benchmarks. 160 161config FUNCTION_GRAPH_TRACER 162 bool "Kernel Function Graph Tracer" 163 depends on HAVE_FUNCTION_GRAPH_TRACER 164 depends on FUNCTION_TRACER 165 depends on !X86_32 || !CC_OPTIMIZE_FOR_SIZE 166 default y 167 help 168 Enable the kernel to trace a function at both its return 169 and its entry. 170 Its first purpose is to trace the duration of functions and 171 draw a call graph for each thread with some information like 172 the return value. This is done by setting the current return 173 address on the current task structure into a stack of calls. 174 175config DYNAMIC_FTRACE 176 bool "enable/disable function tracing dynamically" 177 depends on FUNCTION_TRACER 178 depends on HAVE_DYNAMIC_FTRACE 179 default y 180 help 181 This option will modify all the calls to function tracing 182 dynamically (will patch them out of the binary image and 183 replace them with a No-Op instruction) on boot up. During 184 compile time, a table is made of all the locations that ftrace 185 can function trace, and this table is linked into the kernel 186 image. When this is enabled, functions can be individually 187 enabled, and the functions not enabled will not affect 188 performance of the system. 189 190 See the files in /sys/kernel/debug/tracing: 191 available_filter_functions 192 set_ftrace_filter 193 set_ftrace_notrace 194 195 This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but 196 otherwise has native performance as long as no tracing is active. 197 198config DYNAMIC_FTRACE_WITH_REGS 199 def_bool y 200 depends on DYNAMIC_FTRACE 201 depends on HAVE_DYNAMIC_FTRACE_WITH_REGS 202 203config DYNAMIC_FTRACE_WITH_DIRECT_CALLS 204 def_bool y 205 depends on DYNAMIC_FTRACE 206 depends on HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 207 208config FUNCTION_PROFILER 209 bool "Kernel function profiler" 210 depends on FUNCTION_TRACER 211 default n 212 help 213 This option enables the kernel function profiler. A file is created 214 in debugfs called function_profile_enabled which defaults to zero. 215 When a 1 is echoed into this file profiling begins, and when a 216 zero is entered, profiling stops. A "functions" file is created in 217 the trace_stat directory; this file shows the list of functions that 218 have been hit and their counters. 219 220 If in doubt, say N. 221 222config STACK_TRACER 223 bool "Trace max stack" 224 depends on HAVE_FUNCTION_TRACER 225 select FUNCTION_TRACER 226 select STACKTRACE 227 select KALLSYMS 228 help 229 This special tracer records the maximum stack footprint of the 230 kernel and displays it in /sys/kernel/debug/tracing/stack_trace. 231 232 This tracer works by hooking into every function call that the 233 kernel executes, and keeping a maximum stack depth value and 234 stack-trace saved. If this is configured with DYNAMIC_FTRACE 235 then it will not have any overhead while the stack tracer 236 is disabled. 237 238 To enable the stack tracer on bootup, pass in 'stacktrace' 239 on the kernel command line. 240 241 The stack tracer can also be enabled or disabled via the 242 sysctl kernel.stack_tracer_enabled 243 244 Say N if unsure. 245 246config TRACE_PREEMPT_TOGGLE 247 bool 248 help 249 Enables hooks which will be called when preemption is first disabled, 250 and last enabled. 251 252config PREEMPTIRQ_EVENTS 253 bool "Enable trace events for preempt and irq disable/enable" 254 select TRACE_IRQFLAGS 255 select TRACE_PREEMPT_TOGGLE if PREEMPTION 256 select GENERIC_TRACER 257 default n 258 help 259 Enable tracing of disable and enable events for preemption and irqs. 260 261config IRQSOFF_TRACER 262 bool "Interrupts-off Latency Tracer" 263 default n 264 depends on TRACE_IRQFLAGS_SUPPORT 265 depends on !ARCH_USES_GETTIMEOFFSET 266 select TRACE_IRQFLAGS 267 select GENERIC_TRACER 268 select TRACER_MAX_TRACE 269 select RING_BUFFER_ALLOW_SWAP 270 select TRACER_SNAPSHOT 271 select TRACER_SNAPSHOT_PER_CPU_SWAP 272 help 273 This option measures the time spent in irqs-off critical 274 sections, with microsecond accuracy. 275 276 The default measurement method is a maximum search, which is 277 disabled by default and can be runtime (re-)started 278 via: 279 280 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency 281 282 (Note that kernel size and overhead increase with this option 283 enabled. This option and the preempt-off timing option can be 284 used together or separately.) 285 286config PREEMPT_TRACER 287 bool "Preemption-off Latency Tracer" 288 default n 289 depends on !ARCH_USES_GETTIMEOFFSET 290 depends on PREEMPTION 291 select GENERIC_TRACER 292 select TRACER_MAX_TRACE 293 select RING_BUFFER_ALLOW_SWAP 294 select TRACER_SNAPSHOT 295 select TRACER_SNAPSHOT_PER_CPU_SWAP 296 select TRACE_PREEMPT_TOGGLE 297 help 298 This option measures the time spent in preemption-off critical 299 sections, with microsecond accuracy. 300 301 The default measurement method is a maximum search, which is 302 disabled by default and can be runtime (re-)started 303 via: 304 305 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency 306 307 (Note that kernel size and overhead increase with this option 308 enabled. This option and the irqs-off timing option can be 309 used together or separately.) 310 311config SCHED_TRACER 312 bool "Scheduling Latency Tracer" 313 select GENERIC_TRACER 314 select CONTEXT_SWITCH_TRACER 315 select TRACER_MAX_TRACE 316 select TRACER_SNAPSHOT 317 help 318 This tracer tracks the latency of the highest priority task 319 to be scheduled in, starting from the point it has woken up. 320 321config HWLAT_TRACER 322 bool "Tracer to detect hardware latencies (like SMIs)" 323 select GENERIC_TRACER 324 help 325 This tracer, when enabled will create one or more kernel threads, 326 depending on what the cpumask file is set to, which each thread 327 spinning in a loop looking for interruptions caused by 328 something other than the kernel. For example, if a 329 System Management Interrupt (SMI) takes a noticeable amount of 330 time, this tracer will detect it. This is useful for testing 331 if a system is reliable for Real Time tasks. 332 333 Some files are created in the tracing directory when this 334 is enabled: 335 336 hwlat_detector/width - time in usecs for how long to spin for 337 hwlat_detector/window - time in usecs between the start of each 338 iteration 339 340 A kernel thread is created that will spin with interrupts disabled 341 for "width" microseconds in every "window" cycle. It will not spin 342 for "window - width" microseconds, where the system can 343 continue to operate. 344 345 The output will appear in the trace and trace_pipe files. 346 347 When the tracer is not running, it has no affect on the system, 348 but when it is running, it can cause the system to be 349 periodically non responsive. Do not run this tracer on a 350 production system. 351 352 To enable this tracer, echo in "hwlat" into the current_tracer 353 file. Every time a latency is greater than tracing_thresh, it will 354 be recorded into the ring buffer. 355 356config MMIOTRACE 357 bool "Memory mapped IO tracing" 358 depends on HAVE_MMIOTRACE_SUPPORT && PCI 359 select GENERIC_TRACER 360 help 361 Mmiotrace traces Memory Mapped I/O access and is meant for 362 debugging and reverse engineering. It is called from the ioremap 363 implementation and works via page faults. Tracing is disabled by 364 default and can be enabled at run-time. 365 366 See Documentation/trace/mmiotrace.rst. 367 If you are not helping to develop drivers, say N. 368 369config ENABLE_DEFAULT_TRACERS 370 bool "Trace process context switches and events" 371 depends on !GENERIC_TRACER 372 select TRACING 373 help 374 This tracer hooks to various trace points in the kernel, 375 allowing the user to pick and choose which trace point they 376 want to trace. It also includes the sched_switch tracer plugin. 377 378config FTRACE_SYSCALLS 379 bool "Trace syscalls" 380 depends on HAVE_SYSCALL_TRACEPOINTS 381 select GENERIC_TRACER 382 select KALLSYMS 383 help 384 Basic tracer to catch the syscall entry and exit events. 385 386config TRACER_SNAPSHOT 387 bool "Create a snapshot trace buffer" 388 select TRACER_MAX_TRACE 389 help 390 Allow tracing users to take snapshot of the current buffer using the 391 ftrace interface, e.g.: 392 393 echo 1 > /sys/kernel/debug/tracing/snapshot 394 cat snapshot 395 396config TRACER_SNAPSHOT_PER_CPU_SWAP 397 bool "Allow snapshot to swap per CPU" 398 depends on TRACER_SNAPSHOT 399 select RING_BUFFER_ALLOW_SWAP 400 help 401 Allow doing a snapshot of a single CPU buffer instead of a 402 full swap (all buffers). If this is set, then the following is 403 allowed: 404 405 echo 1 > /sys/kernel/debug/tracing/per_cpu/cpu2/snapshot 406 407 After which, only the tracing buffer for CPU 2 was swapped with 408 the main tracing buffer, and the other CPU buffers remain the same. 409 410 When this is enabled, this adds a little more overhead to the 411 trace recording, as it needs to add some checks to synchronize 412 recording with swaps. But this does not affect the performance 413 of the overall system. This is enabled by default when the preempt 414 or irq latency tracers are enabled, as those need to swap as well 415 and already adds the overhead (plus a lot more). 416 417config TRACE_BRANCH_PROFILING 418 bool 419 select GENERIC_TRACER 420 421choice 422 prompt "Branch Profiling" 423 default BRANCH_PROFILE_NONE 424 help 425 The branch profiling is a software profiler. It will add hooks 426 into the C conditionals to test which path a branch takes. 427 428 The likely/unlikely profiler only looks at the conditions that 429 are annotated with a likely or unlikely macro. 430 431 The "all branch" profiler will profile every if-statement in the 432 kernel. This profiler will also enable the likely/unlikely 433 profiler. 434 435 Either of the above profilers adds a bit of overhead to the system. 436 If unsure, choose "No branch profiling". 437 438config BRANCH_PROFILE_NONE 439 bool "No branch profiling" 440 help 441 No branch profiling. Branch profiling adds a bit of overhead. 442 Only enable it if you want to analyse the branching behavior. 443 Otherwise keep it disabled. 444 445config PROFILE_ANNOTATED_BRANCHES 446 bool "Trace likely/unlikely profiler" 447 select TRACE_BRANCH_PROFILING 448 help 449 This tracer profiles all likely and unlikely macros 450 in the kernel. It will display the results in: 451 452 /sys/kernel/debug/tracing/trace_stat/branch_annotated 453 454 Note: this will add a significant overhead; only turn this 455 on if you need to profile the system's use of these macros. 456 457config PROFILE_ALL_BRANCHES 458 bool "Profile all if conditionals" if !FORTIFY_SOURCE 459 select TRACE_BRANCH_PROFILING 460 imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED # avoid false positives 461 help 462 This tracer profiles all branch conditions. Every if () 463 taken in the kernel is recorded whether it hit or miss. 464 The results will be displayed in: 465 466 /sys/kernel/debug/tracing/trace_stat/branch_all 467 468 This option also enables the likely/unlikely profiler. 469 470 This configuration, when enabled, will impose a great overhead 471 on the system. This should only be enabled when the system 472 is to be analyzed in much detail. 473endchoice 474 475config TRACING_BRANCHES 476 bool 477 help 478 Selected by tracers that will trace the likely and unlikely 479 conditions. This prevents the tracers themselves from being 480 profiled. Profiling the tracing infrastructure can only happen 481 when the likelys and unlikelys are not being traced. 482 483config BRANCH_TRACER 484 bool "Trace likely/unlikely instances" 485 depends on TRACE_BRANCH_PROFILING 486 select TRACING_BRANCHES 487 help 488 This traces the events of likely and unlikely condition 489 calls in the kernel. The difference between this and the 490 "Trace likely/unlikely profiler" is that this is not a 491 histogram of the callers, but actually places the calling 492 events into a running trace buffer to see when and where the 493 events happened, as well as their results. 494 495 Say N if unsure. 496 497config BLK_DEV_IO_TRACE 498 bool "Support for tracing block IO actions" 499 depends on SYSFS 500 depends on BLOCK 501 select RELAY 502 select DEBUG_FS 503 select TRACEPOINTS 504 select GENERIC_TRACER 505 select STACKTRACE 506 help 507 Say Y here if you want to be able to trace the block layer actions 508 on a given queue. Tracing allows you to see any traffic happening 509 on a block device queue. For more information (and the userspace 510 support tools needed), fetch the blktrace tools from: 511 512 git://git.kernel.dk/blktrace.git 513 514 Tracing also is possible using the ftrace interface, e.g.: 515 516 echo 1 > /sys/block/sda/sda1/trace/enable 517 echo blk > /sys/kernel/debug/tracing/current_tracer 518 cat /sys/kernel/debug/tracing/trace_pipe 519 520 If unsure, say N. 521 522config KPROBE_EVENTS 523 depends on KPROBES 524 depends on HAVE_REGS_AND_STACK_ACCESS_API 525 bool "Enable kprobes-based dynamic events" 526 select TRACING 527 select PROBE_EVENTS 528 select DYNAMIC_EVENTS 529 default y 530 help 531 This allows the user to add tracing events (similar to tracepoints) 532 on the fly via the ftrace interface. See 533 Documentation/trace/kprobetrace.rst for more details. 534 535 Those events can be inserted wherever kprobes can probe, and record 536 various register and memory values. 537 538 This option is also required by perf-probe subcommand of perf tools. 539 If you want to use perf tools, this option is strongly recommended. 540 541config KPROBE_EVENTS_ON_NOTRACE 542 bool "Do NOT protect notrace function from kprobe events" 543 depends on KPROBE_EVENTS 544 depends on KPROBES_ON_FTRACE 545 default n 546 help 547 This is only for the developers who want to debug ftrace itself 548 using kprobe events. 549 550 If kprobes can use ftrace instead of breakpoint, ftrace related 551 functions are protected from kprobe-events to prevent an infinit 552 recursion or any unexpected execution path which leads to a kernel 553 crash. 554 555 This option disables such protection and allows you to put kprobe 556 events on ftrace functions for debugging ftrace by itself. 557 Note that this might let you shoot yourself in the foot. 558 559 If unsure, say N. 560 561config UPROBE_EVENTS 562 bool "Enable uprobes-based dynamic events" 563 depends on ARCH_SUPPORTS_UPROBES 564 depends on MMU 565 depends on PERF_EVENTS 566 select UPROBES 567 select PROBE_EVENTS 568 select DYNAMIC_EVENTS 569 select TRACING 570 default y 571 help 572 This allows the user to add tracing events on top of userspace 573 dynamic events (similar to tracepoints) on the fly via the trace 574 events interface. Those events can be inserted wherever uprobes 575 can probe, and record various registers. 576 This option is required if you plan to use perf-probe subcommand 577 of perf tools on user space applications. 578 579config BPF_EVENTS 580 depends on BPF_SYSCALL 581 depends on (KPROBE_EVENTS || UPROBE_EVENTS) && PERF_EVENTS 582 bool 583 default y 584 help 585 This allows the user to attach BPF programs to kprobe, uprobe, and 586 tracepoint events. 587 588config DYNAMIC_EVENTS 589 def_bool n 590 591config PROBE_EVENTS 592 def_bool n 593 594config BPF_KPROBE_OVERRIDE 595 bool "Enable BPF programs to override a kprobed function" 596 depends on BPF_EVENTS 597 depends on FUNCTION_ERROR_INJECTION 598 default n 599 help 600 Allows BPF to override the execution of a probed function and 601 set a different return value. This is used for error injection. 602 603config FTRACE_MCOUNT_RECORD 604 def_bool y 605 depends on DYNAMIC_FTRACE 606 depends on HAVE_FTRACE_MCOUNT_RECORD 607 608config FTRACE_SELFTEST 609 bool 610 611config FTRACE_STARTUP_TEST 612 bool "Perform a startup test on ftrace" 613 depends on GENERIC_TRACER 614 select FTRACE_SELFTEST 615 help 616 This option performs a series of startup tests on ftrace. On bootup 617 a series of tests are made to verify that the tracer is 618 functioning properly. It will do tests on all the configured 619 tracers of ftrace. 620 621config EVENT_TRACE_STARTUP_TEST 622 bool "Run selftest on trace events" 623 depends on FTRACE_STARTUP_TEST 624 default y 625 help 626 This option performs a test on all trace events in the system. 627 It basically just enables each event and runs some code that 628 will trigger events (not necessarily the event it enables) 629 This may take some time run as there are a lot of events. 630 631config EVENT_TRACE_TEST_SYSCALLS 632 bool "Run selftest on syscall events" 633 depends on EVENT_TRACE_STARTUP_TEST 634 help 635 This option will also enable testing every syscall event. 636 It only enables the event and disables it and runs various loads 637 with the event enabled. This adds a bit more time for kernel boot 638 up since it runs this on every system call defined. 639 640 TBD - enable a way to actually call the syscalls as we test their 641 events 642 643config TRACING_MAP 644 bool 645 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG 646 help 647 tracing_map is a special-purpose lock-free map for tracing, 648 separated out as a stand-alone facility in order to allow it 649 to be shared between multiple tracers. It isn't meant to be 650 generally used outside of that context, and is normally 651 selected by tracers that use it. 652 653config HIST_TRIGGERS 654 bool "Histogram triggers" 655 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG 656 select TRACING_MAP 657 select TRACING 658 select DYNAMIC_EVENTS 659 default n 660 help 661 Hist triggers allow one or more arbitrary trace event fields 662 to be aggregated into hash tables and dumped to stdout by 663 reading a debugfs/tracefs file. They're useful for 664 gathering quick and dirty (though precise) summaries of 665 event activity as an initial guide for further investigation 666 using more advanced tools. 667 668 Inter-event tracing of quantities such as latencies is also 669 supported using hist triggers under this option. 670 671 See Documentation/trace/histogram.rst. 672 If in doubt, say N. 673 674config TRACE_EVENT_INJECT 675 bool "Trace event injection" 676 depends on TRACING 677 help 678 Allow user-space to inject a specific trace event into the ring 679 buffer. This is mainly used for testing purpose. 680 681 If unsure, say N. 682 683config TRACEPOINT_BENCHMARK 684 bool "Add tracepoint that benchmarks tracepoints" 685 help 686 This option creates the tracepoint "benchmark:benchmark_event". 687 When the tracepoint is enabled, it kicks off a kernel thread that 688 goes into an infinite loop (calling cond_sched() to let other tasks 689 run), and calls the tracepoint. Each iteration will record the time 690 it took to write to the tracepoint and the next iteration that 691 data will be passed to the tracepoint itself. That is, the tracepoint 692 will report the time it took to do the previous tracepoint. 693 The string written to the tracepoint is a static string of 128 bytes 694 to keep the time the same. The initial string is simply a write of 695 "START". The second string records the cold cache time of the first 696 write which is not added to the rest of the calculations. 697 698 As it is a tight loop, it benchmarks as hot cache. That's fine because 699 we care most about hot paths that are probably in cache already. 700 701 An example of the output: 702 703 START 704 first=3672 [COLD CACHED] 705 last=632 first=3672 max=632 min=632 avg=316 std=446 std^2=199712 706 last=278 first=3672 max=632 min=278 avg=303 std=316 std^2=100337 707 last=277 first=3672 max=632 min=277 avg=296 std=258 std^2=67064 708 last=273 first=3672 max=632 min=273 avg=292 std=224 std^2=50411 709 last=273 first=3672 max=632 min=273 avg=288 std=200 std^2=40389 710 last=281 first=3672 max=632 min=273 avg=287 std=183 std^2=33666 711 712 713config RING_BUFFER_BENCHMARK 714 tristate "Ring buffer benchmark stress tester" 715 depends on RING_BUFFER 716 help 717 This option creates a test to stress the ring buffer and benchmark it. 718 It creates its own ring buffer such that it will not interfere with 719 any other users of the ring buffer (such as ftrace). It then creates 720 a producer and consumer that will run for 10 seconds and sleep for 721 10 seconds. Each interval it will print out the number of events 722 it recorded and give a rough estimate of how long each iteration took. 723 724 It does not disable interrupts or raise its priority, so it may be 725 affected by processes that are running. 726 727 If unsure, say N. 728 729config RING_BUFFER_STARTUP_TEST 730 bool "Ring buffer startup self test" 731 depends on RING_BUFFER 732 help 733 Run a simple self test on the ring buffer on boot up. Late in the 734 kernel boot sequence, the test will start that kicks off 735 a thread per cpu. Each thread will write various size events 736 into the ring buffer. Another thread is created to send IPIs 737 to each of the threads, where the IPI handler will also write 738 to the ring buffer, to test/stress the nesting ability. 739 If any anomalies are discovered, a warning will be displayed 740 and all ring buffers will be disabled. 741 742 The test runs for 10 seconds. This will slow your boot time 743 by at least 10 more seconds. 744 745 At the end of the test, statics and more checks are done. 746 It will output the stats of each per cpu buffer. What 747 was written, the sizes, what was read, what was lost, and 748 other similar details. 749 750 If unsure, say N 751 752config MMIOTRACE_TEST 753 tristate "Test module for mmiotrace" 754 depends on MMIOTRACE && m 755 help 756 This is a dumb module for testing mmiotrace. It is very dangerous 757 as it will write garbage to IO memory starting at a given address. 758 However, it should be safe to use on e.g. unused portion of VRAM. 759 760 Say N, unless you absolutely know what you are doing. 761 762config PREEMPTIRQ_DELAY_TEST 763 tristate "Test module to create a preempt / IRQ disable delay thread to test latency tracers" 764 depends on m 765 help 766 Select this option to build a test module that can help test latency 767 tracers by executing a preempt or irq disable section with a user 768 configurable delay. The module busy waits for the duration of the 769 critical section. 770 771 For example, the following invocation generates a burst of three 772 irq-disabled critical sections for 500us: 773 modprobe preemptirq_delay_test test_mode=irq delay=500 burst_size=3 774 775 If unsure, say N 776 777config SYNTH_EVENT_GEN_TEST 778 tristate "Test module for in-kernel synthetic event generation" 779 depends on HIST_TRIGGERS 780 help 781 This option creates a test module to check the base 782 functionality of in-kernel synthetic event definition and 783 generation. 784 785 To test, insert the module, and then check the trace buffer 786 for the generated sample events. 787 788 If unsure, say N. 789 790config KPROBE_EVENT_GEN_TEST 791 tristate "Test module for in-kernel kprobe event generation" 792 depends on KPROBE_EVENTS 793 help 794 This option creates a test module to check the base 795 functionality of in-kernel kprobe event definition. 796 797 To test, insert the module, and then check the trace buffer 798 for the generated kprobe events. 799 800 If unsure, say N. 801 802config TRACE_EVAL_MAP_FILE 803 bool "Show eval mappings for trace events" 804 depends on TRACING 805 help 806 The "print fmt" of the trace events will show the enum/sizeof names 807 instead of their values. This can cause problems for user space tools 808 that use this string to parse the raw data as user space does not know 809 how to convert the string to its value. 810 811 To fix this, there's a special macro in the kernel that can be used 812 to convert an enum/sizeof into its value. If this macro is used, then 813 the print fmt strings will be converted to their values. 814 815 If something does not get converted properly, this option can be 816 used to show what enums/sizeof the kernel tried to convert. 817 818 This option is for debugging the conversions. A file is created 819 in the tracing directory called "eval_map" that will show the 820 names matched with their values and what trace event system they 821 belong too. 822 823 Normally, the mapping of the strings to values will be freed after 824 boot up or module load. With this option, they will not be freed, as 825 they are needed for the "eval_map" file. Enabling this option will 826 increase the memory footprint of the running kernel. 827 828 If unsure, say N. 829 830config GCOV_PROFILE_FTRACE 831 bool "Enable GCOV profiling on ftrace subsystem" 832 depends on GCOV_KERNEL 833 help 834 Enable GCOV profiling on ftrace subsystem for checking 835 which functions/lines are tested. 836 837 If unsure, say N. 838 839 Note that on a kernel compiled with this config, ftrace will 840 run significantly slower. 841 842config BOOTTIME_TRACING 843 bool "Boot-time Tracing support" 844 depends on BOOT_CONFIG && TRACING 845 default y 846 help 847 Enable developer to setup ftrace subsystem via supplemental 848 kernel cmdline at boot time for debugging (tracing) driver 849 initialization and boot process. 850 851endif # FTRACE 852 853endif # TRACING_SUPPORT 854 855