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 TRACE_PREEMPT_TOGGLE 176 bool 177 help 178 Enables hooks which will be called when preemption is first disabled, 179 and last enabled. 180 181config PREEMPTIRQ_EVENTS 182 bool "Enable trace events for preempt and irq disable/enable" 183 select TRACE_IRQFLAGS 184 select TRACE_PREEMPT_TOGGLE if PREEMPTION 185 select GENERIC_TRACER 186 default n 187 help 188 Enable tracing of disable and enable events for preemption and irqs. 189 190config IRQSOFF_TRACER 191 bool "Interrupts-off Latency Tracer" 192 default n 193 depends on TRACE_IRQFLAGS_SUPPORT 194 depends on !ARCH_USES_GETTIMEOFFSET 195 select TRACE_IRQFLAGS 196 select GENERIC_TRACER 197 select TRACER_MAX_TRACE 198 select RING_BUFFER_ALLOW_SWAP 199 select TRACER_SNAPSHOT 200 select TRACER_SNAPSHOT_PER_CPU_SWAP 201 help 202 This option measures the time spent in irqs-off critical 203 sections, with microsecond accuracy. 204 205 The default measurement method is a maximum search, which is 206 disabled by default and can be runtime (re-)started 207 via: 208 209 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency 210 211 (Note that kernel size and overhead increase with this option 212 enabled. This option and the preempt-off timing option can be 213 used together or separately.) 214 215config PREEMPT_TRACER 216 bool "Preemption-off Latency Tracer" 217 default n 218 depends on !ARCH_USES_GETTIMEOFFSET 219 depends on PREEMPTION 220 select GENERIC_TRACER 221 select TRACER_MAX_TRACE 222 select RING_BUFFER_ALLOW_SWAP 223 select TRACER_SNAPSHOT 224 select TRACER_SNAPSHOT_PER_CPU_SWAP 225 select TRACE_PREEMPT_TOGGLE 226 help 227 This option measures the time spent in preemption-off critical 228 sections, with microsecond accuracy. 229 230 The default measurement method is a maximum search, which is 231 disabled by default and can be runtime (re-)started 232 via: 233 234 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency 235 236 (Note that kernel size and overhead increase with this option 237 enabled. This option and the irqs-off timing option can be 238 used together or separately.) 239 240config SCHED_TRACER 241 bool "Scheduling Latency Tracer" 242 select GENERIC_TRACER 243 select CONTEXT_SWITCH_TRACER 244 select TRACER_MAX_TRACE 245 select TRACER_SNAPSHOT 246 help 247 This tracer tracks the latency of the highest priority task 248 to be scheduled in, starting from the point it has woken up. 249 250config HWLAT_TRACER 251 bool "Tracer to detect hardware latencies (like SMIs)" 252 select GENERIC_TRACER 253 help 254 This tracer, when enabled will create one or more kernel threads, 255 depending on what the cpumask file is set to, which each thread 256 spinning in a loop looking for interruptions caused by 257 something other than the kernel. For example, if a 258 System Management Interrupt (SMI) takes a noticeable amount of 259 time, this tracer will detect it. This is useful for testing 260 if a system is reliable for Real Time tasks. 261 262 Some files are created in the tracing directory when this 263 is enabled: 264 265 hwlat_detector/width - time in usecs for how long to spin for 266 hwlat_detector/window - time in usecs between the start of each 267 iteration 268 269 A kernel thread is created that will spin with interrupts disabled 270 for "width" microseconds in every "window" cycle. It will not spin 271 for "window - width" microseconds, where the system can 272 continue to operate. 273 274 The output will appear in the trace and trace_pipe files. 275 276 When the tracer is not running, it has no affect on the system, 277 but when it is running, it can cause the system to be 278 periodically non responsive. Do not run this tracer on a 279 production system. 280 281 To enable this tracer, echo in "hwlat" into the current_tracer 282 file. Every time a latency is greater than tracing_thresh, it will 283 be recorded into the ring buffer. 284 285config ENABLE_DEFAULT_TRACERS 286 bool "Trace process context switches and events" 287 depends on !GENERIC_TRACER 288 select TRACING 289 help 290 This tracer hooks to various trace points in the kernel, 291 allowing the user to pick and choose which trace point they 292 want to trace. It also includes the sched_switch tracer plugin. 293 294config FTRACE_SYSCALLS 295 bool "Trace syscalls" 296 depends on HAVE_SYSCALL_TRACEPOINTS 297 select GENERIC_TRACER 298 select KALLSYMS 299 help 300 Basic tracer to catch the syscall entry and exit events. 301 302config TRACER_SNAPSHOT 303 bool "Create a snapshot trace buffer" 304 select TRACER_MAX_TRACE 305 help 306 Allow tracing users to take snapshot of the current buffer using the 307 ftrace interface, e.g.: 308 309 echo 1 > /sys/kernel/debug/tracing/snapshot 310 cat snapshot 311 312config TRACER_SNAPSHOT_PER_CPU_SWAP 313 bool "Allow snapshot to swap per CPU" 314 depends on TRACER_SNAPSHOT 315 select RING_BUFFER_ALLOW_SWAP 316 help 317 Allow doing a snapshot of a single CPU buffer instead of a 318 full swap (all buffers). If this is set, then the following is 319 allowed: 320 321 echo 1 > /sys/kernel/debug/tracing/per_cpu/cpu2/snapshot 322 323 After which, only the tracing buffer for CPU 2 was swapped with 324 the main tracing buffer, and the other CPU buffers remain the same. 325 326 When this is enabled, this adds a little more overhead to the 327 trace recording, as it needs to add some checks to synchronize 328 recording with swaps. But this does not affect the performance 329 of the overall system. This is enabled by default when the preempt 330 or irq latency tracers are enabled, as those need to swap as well 331 and already adds the overhead (plus a lot more). 332 333config TRACE_BRANCH_PROFILING 334 bool 335 select GENERIC_TRACER 336 337choice 338 prompt "Branch Profiling" 339 default BRANCH_PROFILE_NONE 340 help 341 The branch profiling is a software profiler. It will add hooks 342 into the C conditionals to test which path a branch takes. 343 344 The likely/unlikely profiler only looks at the conditions that 345 are annotated with a likely or unlikely macro. 346 347 The "all branch" profiler will profile every if-statement in the 348 kernel. This profiler will also enable the likely/unlikely 349 profiler. 350 351 Either of the above profilers adds a bit of overhead to the system. 352 If unsure, choose "No branch profiling". 353 354config BRANCH_PROFILE_NONE 355 bool "No branch profiling" 356 help 357 No branch profiling. Branch profiling adds a bit of overhead. 358 Only enable it if you want to analyse the branching behavior. 359 Otherwise keep it disabled. 360 361config PROFILE_ANNOTATED_BRANCHES 362 bool "Trace likely/unlikely profiler" 363 select TRACE_BRANCH_PROFILING 364 help 365 This tracer profiles all likely and unlikely macros 366 in the kernel. It will display the results in: 367 368 /sys/kernel/debug/tracing/trace_stat/branch_annotated 369 370 Note: this will add a significant overhead; only turn this 371 on if you need to profile the system's use of these macros. 372 373config PROFILE_ALL_BRANCHES 374 bool "Profile all if conditionals" if !FORTIFY_SOURCE 375 select TRACE_BRANCH_PROFILING 376 imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED # avoid false positives 377 help 378 This tracer profiles all branch conditions. Every if () 379 taken in the kernel is recorded whether it hit or miss. 380 The results will be displayed in: 381 382 /sys/kernel/debug/tracing/trace_stat/branch_all 383 384 This option also enables the likely/unlikely profiler. 385 386 This configuration, when enabled, will impose a great overhead 387 on the system. This should only be enabled when the system 388 is to be analyzed in much detail. 389endchoice 390 391config TRACING_BRANCHES 392 bool 393 help 394 Selected by tracers that will trace the likely and unlikely 395 conditions. This prevents the tracers themselves from being 396 profiled. Profiling the tracing infrastructure can only happen 397 when the likelys and unlikelys are not being traced. 398 399config BRANCH_TRACER 400 bool "Trace likely/unlikely instances" 401 depends on TRACE_BRANCH_PROFILING 402 select TRACING_BRANCHES 403 help 404 This traces the events of likely and unlikely condition 405 calls in the kernel. The difference between this and the 406 "Trace likely/unlikely profiler" is that this is not a 407 histogram of the callers, but actually places the calling 408 events into a running trace buffer to see when and where the 409 events happened, as well as their results. 410 411 Say N if unsure. 412 413config STACK_TRACER 414 bool "Trace max stack" 415 depends on HAVE_FUNCTION_TRACER 416 select FUNCTION_TRACER 417 select STACKTRACE 418 select KALLSYMS 419 help 420 This special tracer records the maximum stack footprint of the 421 kernel and displays it in /sys/kernel/debug/tracing/stack_trace. 422 423 This tracer works by hooking into every function call that the 424 kernel executes, and keeping a maximum stack depth value and 425 stack-trace saved. If this is configured with DYNAMIC_FTRACE 426 then it will not have any overhead while the stack tracer 427 is disabled. 428 429 To enable the stack tracer on bootup, pass in 'stacktrace' 430 on the kernel command line. 431 432 The stack tracer can also be enabled or disabled via the 433 sysctl kernel.stack_tracer_enabled 434 435 Say N if unsure. 436 437config BLK_DEV_IO_TRACE 438 bool "Support for tracing block IO actions" 439 depends on SYSFS 440 depends on BLOCK 441 select RELAY 442 select DEBUG_FS 443 select TRACEPOINTS 444 select GENERIC_TRACER 445 select STACKTRACE 446 help 447 Say Y here if you want to be able to trace the block layer actions 448 on a given queue. Tracing allows you to see any traffic happening 449 on a block device queue. For more information (and the userspace 450 support tools needed), fetch the blktrace tools from: 451 452 git://git.kernel.dk/blktrace.git 453 454 Tracing also is possible using the ftrace interface, e.g.: 455 456 echo 1 > /sys/block/sda/sda1/trace/enable 457 echo blk > /sys/kernel/debug/tracing/current_tracer 458 cat /sys/kernel/debug/tracing/trace_pipe 459 460 If unsure, say N. 461 462config KPROBE_EVENTS 463 depends on KPROBES 464 depends on HAVE_REGS_AND_STACK_ACCESS_API 465 bool "Enable kprobes-based dynamic events" 466 select TRACING 467 select PROBE_EVENTS 468 select DYNAMIC_EVENTS 469 default y 470 help 471 This allows the user to add tracing events (similar to tracepoints) 472 on the fly via the ftrace interface. See 473 Documentation/trace/kprobetrace.rst for more details. 474 475 Those events can be inserted wherever kprobes can probe, and record 476 various register and memory values. 477 478 This option is also required by perf-probe subcommand of perf tools. 479 If you want to use perf tools, this option is strongly recommended. 480 481config KPROBE_EVENTS_ON_NOTRACE 482 bool "Do NOT protect notrace function from kprobe events" 483 depends on KPROBE_EVENTS 484 depends on KPROBES_ON_FTRACE 485 default n 486 help 487 This is only for the developers who want to debug ftrace itself 488 using kprobe events. 489 490 If kprobes can use ftrace instead of breakpoint, ftrace related 491 functions are protected from kprobe-events to prevent an infinit 492 recursion or any unexpected execution path which leads to a kernel 493 crash. 494 495 This option disables such protection and allows you to put kprobe 496 events on ftrace functions for debugging ftrace by itself. 497 Note that this might let you shoot yourself in the foot. 498 499 If unsure, say N. 500 501config UPROBE_EVENTS 502 bool "Enable uprobes-based dynamic events" 503 depends on ARCH_SUPPORTS_UPROBES 504 depends on MMU 505 depends on PERF_EVENTS 506 select UPROBES 507 select PROBE_EVENTS 508 select DYNAMIC_EVENTS 509 select TRACING 510 default y 511 help 512 This allows the user to add tracing events on top of userspace 513 dynamic events (similar to tracepoints) on the fly via the trace 514 events interface. Those events can be inserted wherever uprobes 515 can probe, and record various registers. 516 This option is required if you plan to use perf-probe subcommand 517 of perf tools on user space applications. 518 519config BPF_EVENTS 520 depends on BPF_SYSCALL 521 depends on (KPROBE_EVENTS || UPROBE_EVENTS) && PERF_EVENTS 522 bool 523 default y 524 help 525 This allows the user to attach BPF programs to kprobe, uprobe, and 526 tracepoint events. 527 528config DYNAMIC_EVENTS 529 def_bool n 530 531config PROBE_EVENTS 532 def_bool n 533 534config DYNAMIC_FTRACE 535 bool "enable/disable function tracing dynamically" 536 depends on FUNCTION_TRACER 537 depends on HAVE_DYNAMIC_FTRACE 538 default y 539 help 540 This option will modify all the calls to function tracing 541 dynamically (will patch them out of the binary image and 542 replace them with a No-Op instruction) on boot up. During 543 compile time, a table is made of all the locations that ftrace 544 can function trace, and this table is linked into the kernel 545 image. When this is enabled, functions can be individually 546 enabled, and the functions not enabled will not affect 547 performance of the system. 548 549 See the files in /sys/kernel/debug/tracing: 550 available_filter_functions 551 set_ftrace_filter 552 set_ftrace_notrace 553 554 This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but 555 otherwise has native performance as long as no tracing is active. 556 557config DYNAMIC_FTRACE_WITH_REGS 558 def_bool y 559 depends on DYNAMIC_FTRACE 560 depends on HAVE_DYNAMIC_FTRACE_WITH_REGS 561 562config DYNAMIC_FTRACE_WITH_DIRECT_CALLS 563 def_bool y 564 depends on DYNAMIC_FTRACE 565 depends on HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS 566 567config FUNCTION_PROFILER 568 bool "Kernel function profiler" 569 depends on FUNCTION_TRACER 570 default n 571 help 572 This option enables the kernel function profiler. A file is created 573 in debugfs called function_profile_enabled which defaults to zero. 574 When a 1 is echoed into this file profiling begins, and when a 575 zero is entered, profiling stops. A "functions" file is created in 576 the trace_stat directory; this file shows the list of functions that 577 have been hit and their counters. 578 579 If in doubt, say N. 580 581config BPF_KPROBE_OVERRIDE 582 bool "Enable BPF programs to override a kprobed function" 583 depends on BPF_EVENTS 584 depends on FUNCTION_ERROR_INJECTION 585 default n 586 help 587 Allows BPF to override the execution of a probed function and 588 set a different return value. This is used for error injection. 589 590config FTRACE_MCOUNT_RECORD 591 def_bool y 592 depends on DYNAMIC_FTRACE 593 depends on HAVE_FTRACE_MCOUNT_RECORD 594 595config FTRACE_SELFTEST 596 bool 597 598config FTRACE_STARTUP_TEST 599 bool "Perform a startup test on ftrace" 600 depends on GENERIC_TRACER 601 select FTRACE_SELFTEST 602 help 603 This option performs a series of startup tests on ftrace. On bootup 604 a series of tests are made to verify that the tracer is 605 functioning properly. It will do tests on all the configured 606 tracers of ftrace. 607 608config EVENT_TRACE_STARTUP_TEST 609 bool "Run selftest on trace events" 610 depends on FTRACE_STARTUP_TEST 611 default y 612 help 613 This option performs a test on all trace events in the system. 614 It basically just enables each event and runs some code that 615 will trigger events (not necessarily the event it enables) 616 This may take some time run as there are a lot of events. 617 618config EVENT_TRACE_TEST_SYSCALLS 619 bool "Run selftest on syscall events" 620 depends on EVENT_TRACE_STARTUP_TEST 621 help 622 This option will also enable testing every syscall event. 623 It only enables the event and disables it and runs various loads 624 with the event enabled. This adds a bit more time for kernel boot 625 up since it runs this on every system call defined. 626 627 TBD - enable a way to actually call the syscalls as we test their 628 events 629 630config MMIOTRACE 631 bool "Memory mapped IO tracing" 632 depends on HAVE_MMIOTRACE_SUPPORT && PCI 633 select GENERIC_TRACER 634 help 635 Mmiotrace traces Memory Mapped I/O access and is meant for 636 debugging and reverse engineering. It is called from the ioremap 637 implementation and works via page faults. Tracing is disabled by 638 default and can be enabled at run-time. 639 640 See Documentation/trace/mmiotrace.rst. 641 If you are not helping to develop drivers, say N. 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 MMIOTRACE_TEST 675 tristate "Test module for mmiotrace" 676 depends on MMIOTRACE && m 677 help 678 This is a dumb module for testing mmiotrace. It is very dangerous 679 as it will write garbage to IO memory starting at a given address. 680 However, it should be safe to use on e.g. unused portion of VRAM. 681 682 Say N, unless you absolutely know what you are doing. 683 684config TRACEPOINT_BENCHMARK 685 bool "Add tracepoint that benchmarks tracepoints" 686 help 687 This option creates the tracepoint "benchmark:benchmark_event". 688 When the tracepoint is enabled, it kicks off a kernel thread that 689 goes into an infinite loop (calling cond_sched() to let other tasks 690 run), and calls the tracepoint. Each iteration will record the time 691 it took to write to the tracepoint and the next iteration that 692 data will be passed to the tracepoint itself. That is, the tracepoint 693 will report the time it took to do the previous tracepoint. 694 The string written to the tracepoint is a static string of 128 bytes 695 to keep the time the same. The initial string is simply a write of 696 "START". The second string records the cold cache time of the first 697 write which is not added to the rest of the calculations. 698 699 As it is a tight loop, it benchmarks as hot cache. That's fine because 700 we care most about hot paths that are probably in cache already. 701 702 An example of the output: 703 704 START 705 first=3672 [COLD CACHED] 706 last=632 first=3672 max=632 min=632 avg=316 std=446 std^2=199712 707 last=278 first=3672 max=632 min=278 avg=303 std=316 std^2=100337 708 last=277 first=3672 max=632 min=277 avg=296 std=258 std^2=67064 709 last=273 first=3672 max=632 min=273 avg=292 std=224 std^2=50411 710 last=273 first=3672 max=632 min=273 avg=288 std=200 std^2=40389 711 last=281 first=3672 max=632 min=273 avg=287 std=183 std^2=33666 712 713 714config RING_BUFFER_BENCHMARK 715 tristate "Ring buffer benchmark stress tester" 716 depends on RING_BUFFER 717 help 718 This option creates a test to stress the ring buffer and benchmark it. 719 It creates its own ring buffer such that it will not interfere with 720 any other users of the ring buffer (such as ftrace). It then creates 721 a producer and consumer that will run for 10 seconds and sleep for 722 10 seconds. Each interval it will print out the number of events 723 it recorded and give a rough estimate of how long each iteration took. 724 725 It does not disable interrupts or raise its priority, so it may be 726 affected by processes that are running. 727 728 If unsure, say N. 729 730config RING_BUFFER_STARTUP_TEST 731 bool "Ring buffer startup self test" 732 depends on RING_BUFFER 733 help 734 Run a simple self test on the ring buffer on boot up. Late in the 735 kernel boot sequence, the test will start that kicks off 736 a thread per cpu. Each thread will write various size events 737 into the ring buffer. Another thread is created to send IPIs 738 to each of the threads, where the IPI handler will also write 739 to the ring buffer, to test/stress the nesting ability. 740 If any anomalies are discovered, a warning will be displayed 741 and all ring buffers will be disabled. 742 743 The test runs for 10 seconds. This will slow your boot time 744 by at least 10 more seconds. 745 746 At the end of the test, statics and more checks are done. 747 It will output the stats of each per cpu buffer. What 748 was written, the sizes, what was read, what was lost, and 749 other similar details. 750 751 If unsure, say N 752 753config PREEMPTIRQ_DELAY_TEST 754 tristate "Preempt / IRQ disable delay thread to test latency tracers" 755 depends on m 756 help 757 Select this option to build a test module that can help test latency 758 tracers by executing a preempt or irq disable section with a user 759 configurable delay. The module busy waits for the duration of the 760 critical section. 761 762 For example, the following invocation generates a burst of three 763 irq-disabled critical sections for 500us: 764 modprobe preemptirq_delay_test test_mode=irq delay=500 burst_size=3 765 766 If unsure, say N 767 768config TRACE_EVAL_MAP_FILE 769 bool "Show eval mappings for trace events" 770 depends on TRACING 771 help 772 The "print fmt" of the trace events will show the enum/sizeof names 773 instead of their values. This can cause problems for user space tools 774 that use this string to parse the raw data as user space does not know 775 how to convert the string to its value. 776 777 To fix this, there's a special macro in the kernel that can be used 778 to convert an enum/sizeof into its value. If this macro is used, then 779 the print fmt strings will be converted to their values. 780 781 If something does not get converted properly, this option can be 782 used to show what enums/sizeof the kernel tried to convert. 783 784 This option is for debugging the conversions. A file is created 785 in the tracing directory called "eval_map" that will show the 786 names matched with their values and what trace event system they 787 belong too. 788 789 Normally, the mapping of the strings to values will be freed after 790 boot up or module load. With this option, they will not be freed, as 791 they are needed for the "eval_map" file. Enabling this option will 792 increase the memory footprint of the running kernel. 793 794 If unsure, say N. 795 796config GCOV_PROFILE_FTRACE 797 bool "Enable GCOV profiling on ftrace subsystem" 798 depends on GCOV_KERNEL 799 help 800 Enable GCOV profiling on ftrace subsystem for checking 801 which functions/lines are tested. 802 803 If unsure, say N. 804 805 Note that on a kernel compiled with this config, ftrace will 806 run significantly slower. 807 808endif # FTRACE 809 810endif # TRACING_SUPPORT 811 812