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 PREEMPTION 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 PREEMPTION 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 PREEMPTION 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, uprobe, and 524 tracepoint events. 525 526config DYNAMIC_EVENTS 527 def_bool n 528 529config PROBE_EVENTS 530 def_bool n 531 532config DYNAMIC_FTRACE 533 bool "enable/disable function tracing dynamically" 534 depends on FUNCTION_TRACER 535 depends on HAVE_DYNAMIC_FTRACE 536 default y 537 help 538 This option will modify all the calls to function tracing 539 dynamically (will patch them out of the binary image and 540 replace them with a No-Op instruction) on boot up. During 541 compile time, a table is made of all the locations that ftrace 542 can function trace, and this table is linked into the kernel 543 image. When this is enabled, functions can be individually 544 enabled, and the functions not enabled will not affect 545 performance of the system. 546 547 See the files in /sys/kernel/debug/tracing: 548 available_filter_functions 549 set_ftrace_filter 550 set_ftrace_notrace 551 552 This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but 553 otherwise has native performance as long as no tracing is active. 554 555config DYNAMIC_FTRACE_WITH_REGS 556 def_bool y 557 depends on DYNAMIC_FTRACE 558 depends on HAVE_DYNAMIC_FTRACE_WITH_REGS 559 560config FUNCTION_PROFILER 561 bool "Kernel function profiler" 562 depends on FUNCTION_TRACER 563 default n 564 help 565 This option enables the kernel function profiler. A file is created 566 in debugfs called function_profile_enabled which defaults to zero. 567 When a 1 is echoed into this file profiling begins, and when a 568 zero is entered, profiling stops. A "functions" file is created in 569 the trace_stat directory; this file shows the list of functions that 570 have been hit and their counters. 571 572 If in doubt, say N. 573 574config BPF_KPROBE_OVERRIDE 575 bool "Enable BPF programs to override a kprobed function" 576 depends on BPF_EVENTS 577 depends on FUNCTION_ERROR_INJECTION 578 default n 579 help 580 Allows BPF to override the execution of a probed function and 581 set a different return value. This is used for error injection. 582 583config FTRACE_MCOUNT_RECORD 584 def_bool y 585 depends on DYNAMIC_FTRACE 586 depends on HAVE_FTRACE_MCOUNT_RECORD 587 588config FTRACE_SELFTEST 589 bool 590 591config FTRACE_STARTUP_TEST 592 bool "Perform a startup test on ftrace" 593 depends on GENERIC_TRACER 594 select FTRACE_SELFTEST 595 help 596 This option performs a series of startup tests on ftrace. On bootup 597 a series of tests are made to verify that the tracer is 598 functioning properly. It will do tests on all the configured 599 tracers of ftrace. 600 601config EVENT_TRACE_STARTUP_TEST 602 bool "Run selftest on trace events" 603 depends on FTRACE_STARTUP_TEST 604 default y 605 help 606 This option performs a test on all trace events in the system. 607 It basically just enables each event and runs some code that 608 will trigger events (not necessarily the event it enables) 609 This may take some time run as there are a lot of events. 610 611config EVENT_TRACE_TEST_SYSCALLS 612 bool "Run selftest on syscall events" 613 depends on EVENT_TRACE_STARTUP_TEST 614 help 615 This option will also enable testing every syscall event. 616 It only enables the event and disables it and runs various loads 617 with the event enabled. This adds a bit more time for kernel boot 618 up since it runs this on every system call defined. 619 620 TBD - enable a way to actually call the syscalls as we test their 621 events 622 623config MMIOTRACE 624 bool "Memory mapped IO tracing" 625 depends on HAVE_MMIOTRACE_SUPPORT && PCI 626 select GENERIC_TRACER 627 help 628 Mmiotrace traces Memory Mapped I/O access and is meant for 629 debugging and reverse engineering. It is called from the ioremap 630 implementation and works via page faults. Tracing is disabled by 631 default and can be enabled at run-time. 632 633 See Documentation/trace/mmiotrace.rst. 634 If you are not helping to develop drivers, say N. 635 636config TRACING_MAP 637 bool 638 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG 639 help 640 tracing_map is a special-purpose lock-free map for tracing, 641 separated out as a stand-alone facility in order to allow it 642 to be shared between multiple tracers. It isn't meant to be 643 generally used outside of that context, and is normally 644 selected by tracers that use it. 645 646config HIST_TRIGGERS 647 bool "Histogram triggers" 648 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG 649 select TRACING_MAP 650 select TRACING 651 select DYNAMIC_EVENTS 652 default n 653 help 654 Hist triggers allow one or more arbitrary trace event fields 655 to be aggregated into hash tables and dumped to stdout by 656 reading a debugfs/tracefs file. They're useful for 657 gathering quick and dirty (though precise) summaries of 658 event activity as an initial guide for further investigation 659 using more advanced tools. 660 661 Inter-event tracing of quantities such as latencies is also 662 supported using hist triggers under this option. 663 664 See Documentation/trace/histogram.rst. 665 If in doubt, say N. 666 667config MMIOTRACE_TEST 668 tristate "Test module for mmiotrace" 669 depends on MMIOTRACE && m 670 help 671 This is a dumb module for testing mmiotrace. It is very dangerous 672 as it will write garbage to IO memory starting at a given address. 673 However, it should be safe to use on e.g. unused portion of VRAM. 674 675 Say N, unless you absolutely know what you are doing. 676 677config TRACEPOINT_BENCHMARK 678 bool "Add tracepoint that benchmarks tracepoints" 679 help 680 This option creates the tracepoint "benchmark:benchmark_event". 681 When the tracepoint is enabled, it kicks off a kernel thread that 682 goes into an infinite loop (calling cond_sched() to let other tasks 683 run), and calls the tracepoint. Each iteration will record the time 684 it took to write to the tracepoint and the next iteration that 685 data will be passed to the tracepoint itself. That is, the tracepoint 686 will report the time it took to do the previous tracepoint. 687 The string written to the tracepoint is a static string of 128 bytes 688 to keep the time the same. The initial string is simply a write of 689 "START". The second string records the cold cache time of the first 690 write which is not added to the rest of the calculations. 691 692 As it is a tight loop, it benchmarks as hot cache. That's fine because 693 we care most about hot paths that are probably in cache already. 694 695 An example of the output: 696 697 START 698 first=3672 [COLD CACHED] 699 last=632 first=3672 max=632 min=632 avg=316 std=446 std^2=199712 700 last=278 first=3672 max=632 min=278 avg=303 std=316 std^2=100337 701 last=277 first=3672 max=632 min=277 avg=296 std=258 std^2=67064 702 last=273 first=3672 max=632 min=273 avg=292 std=224 std^2=50411 703 last=273 first=3672 max=632 min=273 avg=288 std=200 std^2=40389 704 last=281 first=3672 max=632 min=273 avg=287 std=183 std^2=33666 705 706 707config RING_BUFFER_BENCHMARK 708 tristate "Ring buffer benchmark stress tester" 709 depends on RING_BUFFER 710 help 711 This option creates a test to stress the ring buffer and benchmark it. 712 It creates its own ring buffer such that it will not interfere with 713 any other users of the ring buffer (such as ftrace). It then creates 714 a producer and consumer that will run for 10 seconds and sleep for 715 10 seconds. Each interval it will print out the number of events 716 it recorded and give a rough estimate of how long each iteration took. 717 718 It does not disable interrupts or raise its priority, so it may be 719 affected by processes that are running. 720 721 If unsure, say N. 722 723config RING_BUFFER_STARTUP_TEST 724 bool "Ring buffer startup self test" 725 depends on RING_BUFFER 726 help 727 Run a simple self test on the ring buffer on boot up. Late in the 728 kernel boot sequence, the test will start that kicks off 729 a thread per cpu. Each thread will write various size events 730 into the ring buffer. Another thread is created to send IPIs 731 to each of the threads, where the IPI handler will also write 732 to the ring buffer, to test/stress the nesting ability. 733 If any anomalies are discovered, a warning will be displayed 734 and all ring buffers will be disabled. 735 736 The test runs for 10 seconds. This will slow your boot time 737 by at least 10 more seconds. 738 739 At the end of the test, statics and more checks are done. 740 It will output the stats of each per cpu buffer. What 741 was written, the sizes, what was read, what was lost, and 742 other similar details. 743 744 If unsure, say N 745 746config PREEMPTIRQ_DELAY_TEST 747 tristate "Preempt / IRQ disable delay thread to test latency tracers" 748 depends on m 749 help 750 Select this option to build a test module that can help test latency 751 tracers by executing a preempt or irq disable section with a user 752 configurable delay. The module busy waits for the duration of the 753 critical section. 754 755 For example, the following invocation forces a one-time irq-disabled 756 critical section for 500us: 757 modprobe preemptirq_delay_test test_mode=irq delay=500000 758 759 If unsure, say N 760 761config TRACE_EVAL_MAP_FILE 762 bool "Show eval mappings for trace events" 763 depends on TRACING 764 help 765 The "print fmt" of the trace events will show the enum/sizeof names 766 instead of their values. This can cause problems for user space tools 767 that use this string to parse the raw data as user space does not know 768 how to convert the string to its value. 769 770 To fix this, there's a special macro in the kernel that can be used 771 to convert an enum/sizeof into its value. If this macro is used, then 772 the print fmt strings will be converted to their values. 773 774 If something does not get converted properly, this option can be 775 used to show what enums/sizeof the kernel tried to convert. 776 777 This option is for debugging the conversions. A file is created 778 in the tracing directory called "eval_map" that will show the 779 names matched with their values and what trace event system they 780 belong too. 781 782 Normally, the mapping of the strings to values will be freed after 783 boot up or module load. With this option, they will not be freed, as 784 they are needed for the "eval_map" file. Enabling this option will 785 increase the memory footprint of the running kernel. 786 787 If unsure, say N 788 789config GCOV_PROFILE_FTRACE 790 bool "Enable GCOV profiling on ftrace subsystem" 791 depends on GCOV_KERNEL 792 help 793 Enable GCOV profiling on ftrace subsystem for checking 794 which functions/lines are tested. 795 796 If unsure, say N. 797 798 Note that on a kernel compiled with this config, ftrace will 799 run significantly slower. 800 801endif # FTRACE 802 803endif # TRACING_SUPPORT 804 805