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_FTRACE_MCOUNT_RECORD 37 bool 38 help 39 See Documentation/trace/ftrace-design.rst 40 41config HAVE_SYSCALL_TRACEPOINTS 42 bool 43 help 44 See Documentation/trace/ftrace-design.rst 45 46config HAVE_FENTRY 47 bool 48 help 49 Arch supports the gcc options -pg with -mfentry 50 51config HAVE_NOP_MCOUNT 52 bool 53 help 54 Arch supports the gcc options -pg with -mrecord-mcount and -nop-mcount 55 56config HAVE_C_RECORDMCOUNT 57 bool 58 help 59 C version of recordmcount available? 60 61config TRACER_MAX_TRACE 62 bool 63 64config TRACE_CLOCK 65 bool 66 67config RING_BUFFER 68 bool 69 select TRACE_CLOCK 70 select IRQ_WORK 71 72config FTRACE_NMI_ENTER 73 bool 74 depends on HAVE_FTRACE_NMI_ENTER 75 default y 76 77config EVENT_TRACING 78 select CONTEXT_SWITCH_TRACER 79 select GLOB 80 bool 81 82config CONTEXT_SWITCH_TRACER 83 bool 84 85config RING_BUFFER_ALLOW_SWAP 86 bool 87 help 88 Allow the use of ring_buffer_swap_cpu. 89 Adds a very slight overhead to tracing when enabled. 90 91config PREEMPTIRQ_TRACEPOINTS 92 bool 93 depends on TRACE_PREEMPT_TOGGLE || TRACE_IRQFLAGS 94 select TRACING 95 default y 96 help 97 Create preempt/irq toggle tracepoints if needed, so that other parts 98 of the kernel can use them to generate or add hooks to them. 99 100# All tracer options should select GENERIC_TRACER. For those options that are 101# enabled by all tracers (context switch and event tracer) they select TRACING. 102# This allows those options to appear when no other tracer is selected. But the 103# options do not appear when something else selects it. We need the two options 104# GENERIC_TRACER and TRACING to avoid circular dependencies to accomplish the 105# hiding of the automatic options. 106 107config TRACING 108 bool 109 select DEBUG_FS 110 select RING_BUFFER 111 select STACKTRACE if STACKTRACE_SUPPORT 112 select TRACEPOINTS 113 select NOP_TRACER 114 select BINARY_PRINTF 115 select EVENT_TRACING 116 select TRACE_CLOCK 117 118config GENERIC_TRACER 119 bool 120 select TRACING 121 122# 123# Minimum requirements an architecture has to meet for us to 124# be able to offer generic tracing facilities: 125# 126config TRACING_SUPPORT 127 bool 128 depends on TRACE_IRQFLAGS_SUPPORT 129 depends on STACKTRACE_SUPPORT 130 default y 131 132if TRACING_SUPPORT 133 134menuconfig FTRACE 135 bool "Tracers" 136 default y if DEBUG_KERNEL 137 help 138 Enable the kernel tracing infrastructure. 139 140if FTRACE 141 142config FUNCTION_TRACER 143 bool "Kernel Function Tracer" 144 depends on HAVE_FUNCTION_TRACER 145 select KALLSYMS 146 select GENERIC_TRACER 147 select CONTEXT_SWITCH_TRACER 148 select GLOB 149 select TASKS_RCU if PREEMPT 150 help 151 Enable the kernel to trace every kernel function. This is done 152 by using a compiler feature to insert a small, 5-byte No-Operation 153 instruction at the beginning of every kernel function, which NOP 154 sequence is then dynamically patched into a tracer call when 155 tracing is enabled by the administrator. If it's runtime disabled 156 (the bootup default), then the overhead of the instructions is very 157 small and not measurable even in micro-benchmarks. 158 159config FUNCTION_GRAPH_TRACER 160 bool "Kernel Function Graph Tracer" 161 depends on HAVE_FUNCTION_GRAPH_TRACER 162 depends on FUNCTION_TRACER 163 depends on !X86_32 || !CC_OPTIMIZE_FOR_SIZE 164 default y 165 help 166 Enable the kernel to trace a function at both its return 167 and its entry. 168 Its first purpose is to trace the duration of functions and 169 draw a call graph for each thread with some information like 170 the return value. This is done by setting the current return 171 address on the current task structure into a stack of calls. 172 173config TRACE_PREEMPT_TOGGLE 174 bool 175 help 176 Enables hooks which will be called when preemption is first disabled, 177 and last enabled. 178 179config PREEMPTIRQ_EVENTS 180 bool "Enable trace events for preempt and irq disable/enable" 181 select TRACE_IRQFLAGS 182 select TRACE_PREEMPT_TOGGLE if PREEMPT 183 select GENERIC_TRACER 184 default n 185 help 186 Enable tracing of disable and enable events for preemption and irqs. 187 188config IRQSOFF_TRACER 189 bool "Interrupts-off Latency Tracer" 190 default n 191 depends on TRACE_IRQFLAGS_SUPPORT 192 depends on !ARCH_USES_GETTIMEOFFSET 193 select TRACE_IRQFLAGS 194 select GENERIC_TRACER 195 select TRACER_MAX_TRACE 196 select RING_BUFFER_ALLOW_SWAP 197 select TRACER_SNAPSHOT 198 select TRACER_SNAPSHOT_PER_CPU_SWAP 199 help 200 This option measures the time spent in irqs-off critical 201 sections, with microsecond accuracy. 202 203 The default measurement method is a maximum search, which is 204 disabled by default and can be runtime (re-)started 205 via: 206 207 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency 208 209 (Note that kernel size and overhead increase with this option 210 enabled. This option and the preempt-off timing option can be 211 used together or separately.) 212 213config PREEMPT_TRACER 214 bool "Preemption-off Latency Tracer" 215 default n 216 depends on !ARCH_USES_GETTIMEOFFSET 217 depends on PREEMPT 218 select GENERIC_TRACER 219 select TRACER_MAX_TRACE 220 select RING_BUFFER_ALLOW_SWAP 221 select TRACER_SNAPSHOT 222 select TRACER_SNAPSHOT_PER_CPU_SWAP 223 select TRACE_PREEMPT_TOGGLE 224 help 225 This option measures the time spent in preemption-off critical 226 sections, with microsecond accuracy. 227 228 The default measurement method is a maximum search, which is 229 disabled by default and can be runtime (re-)started 230 via: 231 232 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency 233 234 (Note that kernel size and overhead increase with this option 235 enabled. This option and the irqs-off timing option can be 236 used together or separately.) 237 238config SCHED_TRACER 239 bool "Scheduling Latency Tracer" 240 select GENERIC_TRACER 241 select CONTEXT_SWITCH_TRACER 242 select TRACER_MAX_TRACE 243 select TRACER_SNAPSHOT 244 help 245 This tracer tracks the latency of the highest priority task 246 to be scheduled in, starting from the point it has woken up. 247 248config HWLAT_TRACER 249 bool "Tracer to detect hardware latencies (like SMIs)" 250 select GENERIC_TRACER 251 help 252 This tracer, when enabled will create one or more kernel threads, 253 depending on what the cpumask file is set to, which each thread 254 spinning in a loop looking for interruptions caused by 255 something other than the kernel. For example, if a 256 System Management Interrupt (SMI) takes a noticeable amount of 257 time, this tracer will detect it. This is useful for testing 258 if a system is reliable for Real Time tasks. 259 260 Some files are created in the tracing directory when this 261 is enabled: 262 263 hwlat_detector/width - time in usecs for how long to spin for 264 hwlat_detector/window - time in usecs between the start of each 265 iteration 266 267 A kernel thread is created that will spin with interrupts disabled 268 for "width" microseconds in every "window" cycle. It will not spin 269 for "window - width" microseconds, where the system can 270 continue to operate. 271 272 The output will appear in the trace and trace_pipe files. 273 274 When the tracer is not running, it has no affect on the system, 275 but when it is running, it can cause the system to be 276 periodically non responsive. Do not run this tracer on a 277 production system. 278 279 To enable this tracer, echo in "hwlat" into the current_tracer 280 file. Every time a latency is greater than tracing_thresh, it will 281 be recorded into the ring buffer. 282 283config ENABLE_DEFAULT_TRACERS 284 bool "Trace process context switches and events" 285 depends on !GENERIC_TRACER 286 select TRACING 287 help 288 This tracer hooks to various trace points in the kernel, 289 allowing the user to pick and choose which trace point they 290 want to trace. It also includes the sched_switch tracer plugin. 291 292config FTRACE_SYSCALLS 293 bool "Trace syscalls" 294 depends on HAVE_SYSCALL_TRACEPOINTS 295 select GENERIC_TRACER 296 select KALLSYMS 297 help 298 Basic tracer to catch the syscall entry and exit events. 299 300config TRACER_SNAPSHOT 301 bool "Create a snapshot trace buffer" 302 select TRACER_MAX_TRACE 303 help 304 Allow tracing users to take snapshot of the current buffer using the 305 ftrace interface, e.g.: 306 307 echo 1 > /sys/kernel/debug/tracing/snapshot 308 cat snapshot 309 310config TRACER_SNAPSHOT_PER_CPU_SWAP 311 bool "Allow snapshot to swap per CPU" 312 depends on TRACER_SNAPSHOT 313 select RING_BUFFER_ALLOW_SWAP 314 help 315 Allow doing a snapshot of a single CPU buffer instead of a 316 full swap (all buffers). If this is set, then the following is 317 allowed: 318 319 echo 1 > /sys/kernel/debug/tracing/per_cpu/cpu2/snapshot 320 321 After which, only the tracing buffer for CPU 2 was swapped with 322 the main tracing buffer, and the other CPU buffers remain the same. 323 324 When this is enabled, this adds a little more overhead to the 325 trace recording, as it needs to add some checks to synchronize 326 recording with swaps. But this does not affect the performance 327 of the overall system. This is enabled by default when the preempt 328 or irq latency tracers are enabled, as those need to swap as well 329 and already adds the overhead (plus a lot more). 330 331config TRACE_BRANCH_PROFILING 332 bool 333 select GENERIC_TRACER 334 335choice 336 prompt "Branch Profiling" 337 default BRANCH_PROFILE_NONE 338 help 339 The branch profiling is a software profiler. It will add hooks 340 into the C conditionals to test which path a branch takes. 341 342 The likely/unlikely profiler only looks at the conditions that 343 are annotated with a likely or unlikely macro. 344 345 The "all branch" profiler will profile every if-statement in the 346 kernel. This profiler will also enable the likely/unlikely 347 profiler. 348 349 Either of the above profilers adds a bit of overhead to the system. 350 If unsure, choose "No branch profiling". 351 352config BRANCH_PROFILE_NONE 353 bool "No branch profiling" 354 help 355 No branch profiling. Branch profiling adds a bit of overhead. 356 Only enable it if you want to analyse the branching behavior. 357 Otherwise keep it disabled. 358 359config PROFILE_ANNOTATED_BRANCHES 360 bool "Trace likely/unlikely profiler" 361 select TRACE_BRANCH_PROFILING 362 help 363 This tracer profiles all likely and unlikely macros 364 in the kernel. It will display the results in: 365 366 /sys/kernel/debug/tracing/trace_stat/branch_annotated 367 368 Note: this will add a significant overhead; only turn this 369 on if you need to profile the system's use of these macros. 370 371config PROFILE_ALL_BRANCHES 372 bool "Profile all if conditionals" if !FORTIFY_SOURCE 373 select TRACE_BRANCH_PROFILING 374 imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED # avoid false positives 375 help 376 This tracer profiles all branch conditions. Every if () 377 taken in the kernel is recorded whether it hit or miss. 378 The results will be displayed in: 379 380 /sys/kernel/debug/tracing/trace_stat/branch_all 381 382 This option also enables the likely/unlikely profiler. 383 384 This configuration, when enabled, will impose a great overhead 385 on the system. This should only be enabled when the system 386 is to be analyzed in much detail. 387endchoice 388 389config TRACING_BRANCHES 390 bool 391 help 392 Selected by tracers that will trace the likely and unlikely 393 conditions. This prevents the tracers themselves from being 394 profiled. Profiling the tracing infrastructure can only happen 395 when the likelys and unlikelys are not being traced. 396 397config BRANCH_TRACER 398 bool "Trace likely/unlikely instances" 399 depends on TRACE_BRANCH_PROFILING 400 select TRACING_BRANCHES 401 help 402 This traces the events of likely and unlikely condition 403 calls in the kernel. The difference between this and the 404 "Trace likely/unlikely profiler" is that this is not a 405 histogram of the callers, but actually places the calling 406 events into a running trace buffer to see when and where the 407 events happened, as well as their results. 408 409 Say N if unsure. 410 411config STACK_TRACER 412 bool "Trace max stack" 413 depends on HAVE_FUNCTION_TRACER 414 select FUNCTION_TRACER 415 select STACKTRACE 416 select KALLSYMS 417 help 418 This special tracer records the maximum stack footprint of the 419 kernel and displays it in /sys/kernel/debug/tracing/stack_trace. 420 421 This tracer works by hooking into every function call that the 422 kernel executes, and keeping a maximum stack depth value and 423 stack-trace saved. If this is configured with DYNAMIC_FTRACE 424 then it will not have any overhead while the stack tracer 425 is disabled. 426 427 To enable the stack tracer on bootup, pass in 'stacktrace' 428 on the kernel command line. 429 430 The stack tracer can also be enabled or disabled via the 431 sysctl kernel.stack_tracer_enabled 432 433 Say N if unsure. 434 435config BLK_DEV_IO_TRACE 436 bool "Support for tracing block IO actions" 437 depends on SYSFS 438 depends on BLOCK 439 select RELAY 440 select DEBUG_FS 441 select TRACEPOINTS 442 select GENERIC_TRACER 443 select STACKTRACE 444 help 445 Say Y here if you want to be able to trace the block layer actions 446 on a given queue. Tracing allows you to see any traffic happening 447 on a block device queue. For more information (and the userspace 448 support tools needed), fetch the blktrace tools from: 449 450 git://git.kernel.dk/blktrace.git 451 452 Tracing also is possible using the ftrace interface, e.g.: 453 454 echo 1 > /sys/block/sda/sda1/trace/enable 455 echo blk > /sys/kernel/debug/tracing/current_tracer 456 cat /sys/kernel/debug/tracing/trace_pipe 457 458 If unsure, say N. 459 460config KPROBE_EVENTS 461 depends on KPROBES 462 depends on HAVE_REGS_AND_STACK_ACCESS_API 463 bool "Enable kprobes-based dynamic events" 464 select TRACING 465 select PROBE_EVENTS 466 select DYNAMIC_EVENTS 467 default y 468 help 469 This allows the user to add tracing events (similar to tracepoints) 470 on the fly via the ftrace interface. See 471 Documentation/trace/kprobetrace.rst for more details. 472 473 Those events can be inserted wherever kprobes can probe, and record 474 various register and memory values. 475 476 This option is also required by perf-probe subcommand of perf tools. 477 If you want to use perf tools, this option is strongly recommended. 478 479config KPROBE_EVENTS_ON_NOTRACE 480 bool "Do NOT protect notrace function from kprobe events" 481 depends on KPROBE_EVENTS 482 depends on KPROBES_ON_FTRACE 483 default n 484 help 485 This is only for the developers who want to debug ftrace itself 486 using kprobe events. 487 488 If kprobes can use ftrace instead of breakpoint, ftrace related 489 functions are protected from kprobe-events to prevent an infinit 490 recursion or any unexpected execution path which leads to a kernel 491 crash. 492 493 This option disables such protection and allows you to put kprobe 494 events on ftrace functions for debugging ftrace by itself. 495 Note that this might let you shoot yourself in the foot. 496 497 If unsure, say N. 498 499config UPROBE_EVENTS 500 bool "Enable uprobes-based dynamic events" 501 depends on ARCH_SUPPORTS_UPROBES 502 depends on MMU 503 depends on PERF_EVENTS 504 select UPROBES 505 select PROBE_EVENTS 506 select DYNAMIC_EVENTS 507 select TRACING 508 default y 509 help 510 This allows the user to add tracing events on top of userspace 511 dynamic events (similar to tracepoints) on the fly via the trace 512 events interface. Those events can be inserted wherever uprobes 513 can probe, and record various registers. 514 This option is required if you plan to use perf-probe subcommand 515 of perf tools on user space applications. 516 517config BPF_EVENTS 518 depends on BPF_SYSCALL 519 depends on (KPROBE_EVENTS || UPROBE_EVENTS) && PERF_EVENTS 520 bool 521 default y 522 help 523 This allows the user to attach BPF programs to kprobe events. 524 525config DYNAMIC_EVENTS 526 def_bool n 527 528config PROBE_EVENTS 529 def_bool n 530 531config DYNAMIC_FTRACE 532 bool "enable/disable function tracing dynamically" 533 depends on FUNCTION_TRACER 534 depends on HAVE_DYNAMIC_FTRACE 535 default y 536 help 537 This option will modify all the calls to function tracing 538 dynamically (will patch them out of the binary image and 539 replace them with a No-Op instruction) on boot up. During 540 compile time, a table is made of all the locations that ftrace 541 can function trace, and this table is linked into the kernel 542 image. When this is enabled, functions can be individually 543 enabled, and the functions not enabled will not affect 544 performance of the system. 545 546 See the files in /sys/kernel/debug/tracing: 547 available_filter_functions 548 set_ftrace_filter 549 set_ftrace_notrace 550 551 This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but 552 otherwise has native performance as long as no tracing is active. 553 554config DYNAMIC_FTRACE_WITH_REGS 555 def_bool y 556 depends on DYNAMIC_FTRACE 557 depends on HAVE_DYNAMIC_FTRACE_WITH_REGS 558 559config FUNCTION_PROFILER 560 bool "Kernel function profiler" 561 depends on FUNCTION_TRACER 562 default n 563 help 564 This option enables the kernel function profiler. A file is created 565 in debugfs called function_profile_enabled which defaults to zero. 566 When a 1 is echoed into this file profiling begins, and when a 567 zero is entered, profiling stops. A "functions" file is created in 568 the trace_stat directory; this file shows the list of functions that 569 have been hit and their counters. 570 571 If in doubt, say N. 572 573config BPF_KPROBE_OVERRIDE 574 bool "Enable BPF programs to override a kprobed function" 575 depends on BPF_EVENTS 576 depends on FUNCTION_ERROR_INJECTION 577 default n 578 help 579 Allows BPF to override the execution of a probed function and 580 set a different return value. This is used for error injection. 581 582config FTRACE_MCOUNT_RECORD 583 def_bool y 584 depends on DYNAMIC_FTRACE 585 depends on HAVE_FTRACE_MCOUNT_RECORD 586 587config FTRACE_SELFTEST 588 bool 589 590config FTRACE_STARTUP_TEST 591 bool "Perform a startup test on ftrace" 592 depends on GENERIC_TRACER 593 select FTRACE_SELFTEST 594 help 595 This option performs a series of startup tests on ftrace. On bootup 596 a series of tests are made to verify that the tracer is 597 functioning properly. It will do tests on all the configured 598 tracers of ftrace. 599 600config EVENT_TRACE_STARTUP_TEST 601 bool "Run selftest on trace events" 602 depends on FTRACE_STARTUP_TEST 603 default y 604 help 605 This option performs a test on all trace events in the system. 606 It basically just enables each event and runs some code that 607 will trigger events (not necessarily the event it enables) 608 This may take some time run as there are a lot of events. 609 610config EVENT_TRACE_TEST_SYSCALLS 611 bool "Run selftest on syscall events" 612 depends on EVENT_TRACE_STARTUP_TEST 613 help 614 This option will also enable testing every syscall event. 615 It only enables the event and disables it and runs various loads 616 with the event enabled. This adds a bit more time for kernel boot 617 up since it runs this on every system call defined. 618 619 TBD - enable a way to actually call the syscalls as we test their 620 events 621 622config MMIOTRACE 623 bool "Memory mapped IO tracing" 624 depends on HAVE_MMIOTRACE_SUPPORT && PCI 625 select GENERIC_TRACER 626 help 627 Mmiotrace traces Memory Mapped I/O access and is meant for 628 debugging and reverse engineering. It is called from the ioremap 629 implementation and works via page faults. Tracing is disabled by 630 default and can be enabled at run-time. 631 632 See Documentation/trace/mmiotrace.rst. 633 If you are not helping to develop drivers, say N. 634 635config TRACING_MAP 636 bool 637 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG 638 help 639 tracing_map is a special-purpose lock-free map for tracing, 640 separated out as a stand-alone facility in order to allow it 641 to be shared between multiple tracers. It isn't meant to be 642 generally used outside of that context, and is normally 643 selected by tracers that use it. 644 645config HIST_TRIGGERS 646 bool "Histogram triggers" 647 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG 648 select TRACING_MAP 649 select TRACING 650 select DYNAMIC_EVENTS 651 default n 652 help 653 Hist triggers allow one or more arbitrary trace event fields 654 to be aggregated into hash tables and dumped to stdout by 655 reading a debugfs/tracefs file. They're useful for 656 gathering quick and dirty (though precise) summaries of 657 event activity as an initial guide for further investigation 658 using more advanced tools. 659 660 Inter-event tracing of quantities such as latencies is also 661 supported using hist triggers under this option. 662 663 See Documentation/trace/histogram.rst. 664 If in doubt, say N. 665 666config MMIOTRACE_TEST 667 tristate "Test module for mmiotrace" 668 depends on MMIOTRACE && m 669 help 670 This is a dumb module for testing mmiotrace. It is very dangerous 671 as it will write garbage to IO memory starting at a given address. 672 However, it should be safe to use on e.g. unused portion of VRAM. 673 674 Say N, unless you absolutely know what you are doing. 675 676config TRACEPOINT_BENCHMARK 677 bool "Add tracepoint that benchmarks tracepoints" 678 help 679 This option creates the tracepoint "benchmark:benchmark_event". 680 When the tracepoint is enabled, it kicks off a kernel thread that 681 goes into an infinite loop (calling cond_sched() to let other tasks 682 run), and calls the tracepoint. Each iteration will record the time 683 it took to write to the tracepoint and the next iteration that 684 data will be passed to the tracepoint itself. That is, the tracepoint 685 will report the time it took to do the previous tracepoint. 686 The string written to the tracepoint is a static string of 128 bytes 687 to keep the time the same. The initial string is simply a write of 688 "START". The second string records the cold cache time of the first 689 write which is not added to the rest of the calculations. 690 691 As it is a tight loop, it benchmarks as hot cache. That's fine because 692 we care most about hot paths that are probably in cache already. 693 694 An example of the output: 695 696 START 697 first=3672 [COLD CACHED] 698 last=632 first=3672 max=632 min=632 avg=316 std=446 std^2=199712 699 last=278 first=3672 max=632 min=278 avg=303 std=316 std^2=100337 700 last=277 first=3672 max=632 min=277 avg=296 std=258 std^2=67064 701 last=273 first=3672 max=632 min=273 avg=292 std=224 std^2=50411 702 last=273 first=3672 max=632 min=273 avg=288 std=200 std^2=40389 703 last=281 first=3672 max=632 min=273 avg=287 std=183 std^2=33666 704 705 706config RING_BUFFER_BENCHMARK 707 tristate "Ring buffer benchmark stress tester" 708 depends on RING_BUFFER 709 help 710 This option creates a test to stress the ring buffer and benchmark it. 711 It creates its own ring buffer such that it will not interfere with 712 any other users of the ring buffer (such as ftrace). It then creates 713 a producer and consumer that will run for 10 seconds and sleep for 714 10 seconds. Each interval it will print out the number of events 715 it recorded and give a rough estimate of how long each iteration took. 716 717 It does not disable interrupts or raise its priority, so it may be 718 affected by processes that are running. 719 720 If unsure, say N. 721 722config RING_BUFFER_STARTUP_TEST 723 bool "Ring buffer startup self test" 724 depends on RING_BUFFER 725 help 726 Run a simple self test on the ring buffer on boot up. Late in the 727 kernel boot sequence, the test will start that kicks off 728 a thread per cpu. Each thread will write various size events 729 into the ring buffer. Another thread is created to send IPIs 730 to each of the threads, where the IPI handler will also write 731 to the ring buffer, to test/stress the nesting ability. 732 If any anomalies are discovered, a warning will be displayed 733 and all ring buffers will be disabled. 734 735 The test runs for 10 seconds. This will slow your boot time 736 by at least 10 more seconds. 737 738 At the end of the test, statics and more checks are done. 739 It will output the stats of each per cpu buffer. What 740 was written, the sizes, what was read, what was lost, and 741 other similar details. 742 743 If unsure, say N 744 745config PREEMPTIRQ_DELAY_TEST 746 tristate "Preempt / IRQ disable delay thread to test latency tracers" 747 depends on m 748 help 749 Select this option to build a test module that can help test latency 750 tracers by executing a preempt or irq disable section with a user 751 configurable delay. The module busy waits for the duration of the 752 critical section. 753 754 For example, the following invocation forces a one-time irq-disabled 755 critical section for 500us: 756 modprobe preemptirq_delay_test test_mode=irq delay=500000 757 758 If unsure, say N 759 760config TRACE_EVAL_MAP_FILE 761 bool "Show eval mappings for trace events" 762 depends on TRACING 763 help 764 The "print fmt" of the trace events will show the enum/sizeof names 765 instead of their values. This can cause problems for user space tools 766 that use this string to parse the raw data as user space does not know 767 how to convert the string to its value. 768 769 To fix this, there's a special macro in the kernel that can be used 770 to convert an enum/sizeof into its value. If this macro is used, then 771 the print fmt strings will be converted to their values. 772 773 If something does not get converted properly, this option can be 774 used to show what enums/sizeof the kernel tried to convert. 775 776 This option is for debugging the conversions. A file is created 777 in the tracing directory called "eval_map" that will show the 778 names matched with their values and what trace event system they 779 belong too. 780 781 Normally, the mapping of the strings to values will be freed after 782 boot up or module load. With this option, they will not be freed, as 783 they are needed for the "eval_map" file. Enabling this option will 784 increase the memory footprint of the running kernel. 785 786 If unsure, say N 787 788config GCOV_PROFILE_FTRACE 789 bool "Enable GCOV profiling on ftrace subsystem" 790 depends on GCOV_KERNEL 791 help 792 Enable GCOV profiling on ftrace subsystem for checking 793 which functions/lines are tested. 794 795 If unsure, say N. 796 797 Note that on a kernel compiled with this config, ftrace will 798 run significantly slower. 799 800endif # FTRACE 801 802endif # TRACING_SUPPORT 803 804