1# 2# Architectures that offer an FUNCTION_TRACER implementation should 3# select HAVE_FUNCTION_TRACER: 4# 5 6config USER_STACKTRACE_SUPPORT 7 bool 8 9config NOP_TRACER 10 bool 11 12config HAVE_FTRACE_NMI_ENTER 13 bool 14 help 15 See Documentation/trace/ftrace-design.rst 16 17config HAVE_FUNCTION_TRACER 18 bool 19 help 20 See Documentation/trace/ftrace-design.rst 21 22config HAVE_FUNCTION_GRAPH_TRACER 23 bool 24 help 25 See Documentation/trace/ftrace-design.rst 26 27config HAVE_DYNAMIC_FTRACE 28 bool 29 help 30 See Documentation/trace/ftrace-design.rst 31 32config HAVE_DYNAMIC_FTRACE_WITH_REGS 33 bool 34 35config HAVE_FTRACE_MCOUNT_RECORD 36 bool 37 help 38 See Documentation/trace/ftrace-design.rst 39 40config HAVE_SYSCALL_TRACEPOINTS 41 bool 42 help 43 See Documentation/trace/ftrace-design.rst 44 45config HAVE_FENTRY 46 bool 47 help 48 Arch supports the gcc options -pg with -mfentry 49 50config HAVE_NOP_MCOUNT 51 bool 52 help 53 Arch supports the gcc options -pg with -mrecord-mcount and -nop-mcount 54 55config HAVE_C_RECORDMCOUNT 56 bool 57 help 58 C version of recordmcount available? 59 60config TRACER_MAX_TRACE 61 bool 62 63config TRACE_CLOCK 64 bool 65 66config RING_BUFFER 67 bool 68 select TRACE_CLOCK 69 select IRQ_WORK 70 71config FTRACE_NMI_ENTER 72 bool 73 depends on HAVE_FTRACE_NMI_ENTER 74 default y 75 76config EVENT_TRACING 77 select CONTEXT_SWITCH_TRACER 78 select GLOB 79 bool 80 81config CONTEXT_SWITCH_TRACER 82 bool 83 84config RING_BUFFER_ALLOW_SWAP 85 bool 86 help 87 Allow the use of ring_buffer_swap_cpu. 88 Adds a very slight overhead to tracing when enabled. 89 90config PREEMPTIRQ_TRACEPOINTS 91 bool 92 depends on TRACE_PREEMPT_TOGGLE || TRACE_IRQFLAGS 93 select TRACING 94 default y 95 help 96 Create preempt/irq toggle tracepoints if needed, so that other parts 97 of the kernel can use them to generate or add hooks to them. 98 99# All tracer options should select GENERIC_TRACER. For those options that are 100# enabled by all tracers (context switch and event tracer) they select TRACING. 101# This allows those options to appear when no other tracer is selected. But the 102# options do not appear when something else selects it. We need the two options 103# GENERIC_TRACER and TRACING to avoid circular dependencies to accomplish the 104# hiding of the automatic options. 105 106config TRACING 107 bool 108 select DEBUG_FS 109 select RING_BUFFER 110 select STACKTRACE if STACKTRACE_SUPPORT 111 select TRACEPOINTS 112 select NOP_TRACER 113 select BINARY_PRINTF 114 select EVENT_TRACING 115 select TRACE_CLOCK 116 117config GENERIC_TRACER 118 bool 119 select TRACING 120 121# 122# Minimum requirements an architecture has to meet for us to 123# be able to offer generic tracing facilities: 124# 125config TRACING_SUPPORT 126 bool 127 depends on TRACE_IRQFLAGS_SUPPORT 128 depends on STACKTRACE_SUPPORT 129 default y 130 131if TRACING_SUPPORT 132 133menuconfig FTRACE 134 bool "Tracers" 135 default y if DEBUG_KERNEL 136 help 137 Enable the kernel tracing infrastructure. 138 139if FTRACE 140 141config FUNCTION_TRACER 142 bool "Kernel Function Tracer" 143 depends on HAVE_FUNCTION_TRACER 144 select KALLSYMS 145 select GENERIC_TRACER 146 select CONTEXT_SWITCH_TRACER 147 select GLOB 148 select TASKS_RCU if PREEMPT 149 help 150 Enable the kernel to trace every kernel function. This is done 151 by using a compiler feature to insert a small, 5-byte No-Operation 152 instruction at the beginning of every kernel function, which NOP 153 sequence is then dynamically patched into a tracer call when 154 tracing is enabled by the administrator. If it's runtime disabled 155 (the bootup default), then the overhead of the instructions is very 156 small and not measurable even in micro-benchmarks. 157 158config FUNCTION_GRAPH_TRACER 159 bool "Kernel Function Graph Tracer" 160 depends on HAVE_FUNCTION_GRAPH_TRACER 161 depends on FUNCTION_TRACER 162 depends on !X86_32 || !CC_OPTIMIZE_FOR_SIZE 163 default y 164 help 165 Enable the kernel to trace a function at both its return 166 and its entry. 167 Its first purpose is to trace the duration of functions and 168 draw a call graph for each thread with some information like 169 the return value. This is done by setting the current return 170 address on the current task structure into a stack of calls. 171 172config TRACE_PREEMPT_TOGGLE 173 bool 174 help 175 Enables hooks which will be called when preemption is first disabled, 176 and last enabled. 177 178config PREEMPTIRQ_EVENTS 179 bool "Enable trace events for preempt and irq disable/enable" 180 select TRACE_IRQFLAGS 181 select TRACE_PREEMPT_TOGGLE if PREEMPT 182 select GENERIC_TRACER 183 default n 184 help 185 Enable tracing of disable and enable events for preemption and irqs. 186 187config IRQSOFF_TRACER 188 bool "Interrupts-off Latency Tracer" 189 default n 190 depends on TRACE_IRQFLAGS_SUPPORT 191 depends on !ARCH_USES_GETTIMEOFFSET 192 select TRACE_IRQFLAGS 193 select GENERIC_TRACER 194 select TRACER_MAX_TRACE 195 select RING_BUFFER_ALLOW_SWAP 196 select TRACER_SNAPSHOT 197 select TRACER_SNAPSHOT_PER_CPU_SWAP 198 help 199 This option measures the time spent in irqs-off critical 200 sections, with microsecond accuracy. 201 202 The default measurement method is a maximum search, which is 203 disabled by default and can be runtime (re-)started 204 via: 205 206 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency 207 208 (Note that kernel size and overhead increase with this option 209 enabled. This option and the preempt-off timing option can be 210 used together or separately.) 211 212config PREEMPT_TRACER 213 bool "Preemption-off Latency Tracer" 214 default n 215 depends on !ARCH_USES_GETTIMEOFFSET 216 depends on PREEMPT 217 select GENERIC_TRACER 218 select TRACER_MAX_TRACE 219 select RING_BUFFER_ALLOW_SWAP 220 select TRACER_SNAPSHOT 221 select TRACER_SNAPSHOT_PER_CPU_SWAP 222 select TRACE_PREEMPT_TOGGLE 223 help 224 This option measures the time spent in preemption-off critical 225 sections, with microsecond accuracy. 226 227 The default measurement method is a maximum search, which is 228 disabled by default and can be runtime (re-)started 229 via: 230 231 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency 232 233 (Note that kernel size and overhead increase with this option 234 enabled. This option and the irqs-off timing option can be 235 used together or separately.) 236 237config SCHED_TRACER 238 bool "Scheduling Latency Tracer" 239 select GENERIC_TRACER 240 select CONTEXT_SWITCH_TRACER 241 select TRACER_MAX_TRACE 242 select TRACER_SNAPSHOT 243 help 244 This tracer tracks the latency of the highest priority task 245 to be scheduled in, starting from the point it has woken up. 246 247config HWLAT_TRACER 248 bool "Tracer to detect hardware latencies (like SMIs)" 249 select GENERIC_TRACER 250 help 251 This tracer, when enabled will create one or more kernel threads, 252 depending on what the cpumask file is set to, which each thread 253 spinning in a loop looking for interruptions caused by 254 something other than the kernel. For example, if a 255 System Management Interrupt (SMI) takes a noticeable amount of 256 time, this tracer will detect it. This is useful for testing 257 if a system is reliable for Real Time tasks. 258 259 Some files are created in the tracing directory when this 260 is enabled: 261 262 hwlat_detector/width - time in usecs for how long to spin for 263 hwlat_detector/window - time in usecs between the start of each 264 iteration 265 266 A kernel thread is created that will spin with interrupts disabled 267 for "width" microseconds in every "window" cycle. It will not spin 268 for "window - width" microseconds, where the system can 269 continue to operate. 270 271 The output will appear in the trace and trace_pipe files. 272 273 When the tracer is not running, it has no affect on the system, 274 but when it is running, it can cause the system to be 275 periodically non responsive. Do not run this tracer on a 276 production system. 277 278 To enable this tracer, echo in "hwlat" into the current_tracer 279 file. Every time a latency is greater than tracing_thresh, it will 280 be recorded into the ring buffer. 281 282config ENABLE_DEFAULT_TRACERS 283 bool "Trace process context switches and events" 284 depends on !GENERIC_TRACER 285 select TRACING 286 help 287 This tracer hooks to various trace points in the kernel, 288 allowing the user to pick and choose which trace point they 289 want to trace. It also includes the sched_switch tracer plugin. 290 291config FTRACE_SYSCALLS 292 bool "Trace syscalls" 293 depends on HAVE_SYSCALL_TRACEPOINTS 294 select GENERIC_TRACER 295 select KALLSYMS 296 help 297 Basic tracer to catch the syscall entry and exit events. 298 299config TRACER_SNAPSHOT 300 bool "Create a snapshot trace buffer" 301 select TRACER_MAX_TRACE 302 help 303 Allow tracing users to take snapshot of the current buffer using the 304 ftrace interface, e.g.: 305 306 echo 1 > /sys/kernel/debug/tracing/snapshot 307 cat snapshot 308 309config TRACER_SNAPSHOT_PER_CPU_SWAP 310 bool "Allow snapshot to swap per CPU" 311 depends on TRACER_SNAPSHOT 312 select RING_BUFFER_ALLOW_SWAP 313 help 314 Allow doing a snapshot of a single CPU buffer instead of a 315 full swap (all buffers). If this is set, then the following is 316 allowed: 317 318 echo 1 > /sys/kernel/debug/tracing/per_cpu/cpu2/snapshot 319 320 After which, only the tracing buffer for CPU 2 was swapped with 321 the main tracing buffer, and the other CPU buffers remain the same. 322 323 When this is enabled, this adds a little more overhead to the 324 trace recording, as it needs to add some checks to synchronize 325 recording with swaps. But this does not affect the performance 326 of the overall system. This is enabled by default when the preempt 327 or irq latency tracers are enabled, as those need to swap as well 328 and already adds the overhead (plus a lot more). 329 330config TRACE_BRANCH_PROFILING 331 bool 332 select GENERIC_TRACER 333 334choice 335 prompt "Branch Profiling" 336 default BRANCH_PROFILE_NONE 337 help 338 The branch profiling is a software profiler. It will add hooks 339 into the C conditionals to test which path a branch takes. 340 341 The likely/unlikely profiler only looks at the conditions that 342 are annotated with a likely or unlikely macro. 343 344 The "all branch" profiler will profile every if-statement in the 345 kernel. This profiler will also enable the likely/unlikely 346 profiler. 347 348 Either of the above profilers adds a bit of overhead to the system. 349 If unsure, choose "No branch profiling". 350 351config BRANCH_PROFILE_NONE 352 bool "No branch profiling" 353 help 354 No branch profiling. Branch profiling adds a bit of overhead. 355 Only enable it if you want to analyse the branching behavior. 356 Otherwise keep it disabled. 357 358config PROFILE_ANNOTATED_BRANCHES 359 bool "Trace likely/unlikely profiler" 360 select TRACE_BRANCH_PROFILING 361 help 362 This tracer profiles all likely and unlikely macros 363 in the kernel. It will display the results in: 364 365 /sys/kernel/debug/tracing/trace_stat/branch_annotated 366 367 Note: this will add a significant overhead; only turn this 368 on if you need to profile the system's use of these macros. 369 370config PROFILE_ALL_BRANCHES 371 bool "Profile all if conditionals" if !FORTIFY_SOURCE 372 select TRACE_BRANCH_PROFILING 373 imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED # avoid false positives 374 help 375 This tracer profiles all branch conditions. Every if () 376 taken in the kernel is recorded whether it hit or miss. 377 The results will be displayed in: 378 379 /sys/kernel/debug/tracing/trace_stat/branch_all 380 381 This option also enables the likely/unlikely profiler. 382 383 This configuration, when enabled, will impose a great overhead 384 on the system. This should only be enabled when the system 385 is to be analyzed in much detail. 386endchoice 387 388config TRACING_BRANCHES 389 bool 390 help 391 Selected by tracers that will trace the likely and unlikely 392 conditions. This prevents the tracers themselves from being 393 profiled. Profiling the tracing infrastructure can only happen 394 when the likelys and unlikelys are not being traced. 395 396config BRANCH_TRACER 397 bool "Trace likely/unlikely instances" 398 depends on TRACE_BRANCH_PROFILING 399 select TRACING_BRANCHES 400 help 401 This traces the events of likely and unlikely condition 402 calls in the kernel. The difference between this and the 403 "Trace likely/unlikely profiler" is that this is not a 404 histogram of the callers, but actually places the calling 405 events into a running trace buffer to see when and where the 406 events happened, as well as their results. 407 408 Say N if unsure. 409 410config STACK_TRACER 411 bool "Trace max stack" 412 depends on HAVE_FUNCTION_TRACER 413 select FUNCTION_TRACER 414 select STACKTRACE 415 select KALLSYMS 416 help 417 This special tracer records the maximum stack footprint of the 418 kernel and displays it in /sys/kernel/debug/tracing/stack_trace. 419 420 This tracer works by hooking into every function call that the 421 kernel executes, and keeping a maximum stack depth value and 422 stack-trace saved. If this is configured with DYNAMIC_FTRACE 423 then it will not have any overhead while the stack tracer 424 is disabled. 425 426 To enable the stack tracer on bootup, pass in 'stacktrace' 427 on the kernel command line. 428 429 The stack tracer can also be enabled or disabled via the 430 sysctl kernel.stack_tracer_enabled 431 432 Say N if unsure. 433 434config BLK_DEV_IO_TRACE 435 bool "Support for tracing block IO actions" 436 depends on SYSFS 437 depends on BLOCK 438 select RELAY 439 select DEBUG_FS 440 select TRACEPOINTS 441 select GENERIC_TRACER 442 select STACKTRACE 443 help 444 Say Y here if you want to be able to trace the block layer actions 445 on a given queue. Tracing allows you to see any traffic happening 446 on a block device queue. For more information (and the userspace 447 support tools needed), fetch the blktrace tools from: 448 449 git://git.kernel.dk/blktrace.git 450 451 Tracing also is possible using the ftrace interface, e.g.: 452 453 echo 1 > /sys/block/sda/sda1/trace/enable 454 echo blk > /sys/kernel/debug/tracing/current_tracer 455 cat /sys/kernel/debug/tracing/trace_pipe 456 457 If unsure, say N. 458 459config KPROBE_EVENTS 460 depends on KPROBES 461 depends on HAVE_REGS_AND_STACK_ACCESS_API 462 bool "Enable kprobes-based dynamic events" 463 select TRACING 464 select PROBE_EVENTS 465 select DYNAMIC_EVENTS 466 default y 467 help 468 This allows the user to add tracing events (similar to tracepoints) 469 on the fly via the ftrace interface. See 470 Documentation/trace/kprobetrace.rst for more details. 471 472 Those events can be inserted wherever kprobes can probe, and record 473 various register and memory values. 474 475 This option is also required by perf-probe subcommand of perf tools. 476 If you want to use perf tools, this option is strongly recommended. 477 478config KPROBE_EVENTS_ON_NOTRACE 479 bool "Do NOT protect notrace function from kprobe events" 480 depends on KPROBE_EVENTS 481 depends on KPROBES_ON_FTRACE 482 default n 483 help 484 This is only for the developers who want to debug ftrace itself 485 using kprobe events. 486 487 If kprobes can use ftrace instead of breakpoint, ftrace related 488 functions are protected from kprobe-events to prevent an infinit 489 recursion or any unexpected execution path which leads to a kernel 490 crash. 491 492 This option disables such protection and allows you to put kprobe 493 events on ftrace functions for debugging ftrace by itself. 494 Note that this might let you shoot yourself in the foot. 495 496 If unsure, say N. 497 498config UPROBE_EVENTS 499 bool "Enable uprobes-based dynamic events" 500 depends on ARCH_SUPPORTS_UPROBES 501 depends on MMU 502 depends on PERF_EVENTS 503 select UPROBES 504 select PROBE_EVENTS 505 select DYNAMIC_EVENTS 506 select TRACING 507 default y 508 help 509 This allows the user to add tracing events on top of userspace 510 dynamic events (similar to tracepoints) on the fly via the trace 511 events interface. Those events can be inserted wherever uprobes 512 can probe, and record various registers. 513 This option is required if you plan to use perf-probe subcommand 514 of perf tools on user space applications. 515 516config BPF_EVENTS 517 depends on BPF_SYSCALL 518 depends on (KPROBE_EVENTS || UPROBE_EVENTS) && PERF_EVENTS 519 bool 520 default y 521 help 522 This allows the user to attach BPF programs to kprobe events. 523 524config DYNAMIC_EVENTS 525 def_bool n 526 527config PROBE_EVENTS 528 def_bool n 529 530config DYNAMIC_FTRACE 531 bool "enable/disable function tracing dynamically" 532 depends on FUNCTION_TRACER 533 depends on HAVE_DYNAMIC_FTRACE 534 default y 535 help 536 This option will modify all the calls to function tracing 537 dynamically (will patch them out of the binary image and 538 replace them with a No-Op instruction) on boot up. During 539 compile time, a table is made of all the locations that ftrace 540 can function trace, and this table is linked into the kernel 541 image. When this is enabled, functions can be individually 542 enabled, and the functions not enabled will not affect 543 performance of the system. 544 545 See the files in /sys/kernel/debug/tracing: 546 available_filter_functions 547 set_ftrace_filter 548 set_ftrace_notrace 549 550 This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but 551 otherwise has native performance as long as no tracing is active. 552 553config DYNAMIC_FTRACE_WITH_REGS 554 def_bool y 555 depends on DYNAMIC_FTRACE 556 depends on HAVE_DYNAMIC_FTRACE_WITH_REGS 557 558config FUNCTION_PROFILER 559 bool "Kernel function profiler" 560 depends on FUNCTION_TRACER 561 default n 562 help 563 This option enables the kernel function profiler. A file is created 564 in debugfs called function_profile_enabled which defaults to zero. 565 When a 1 is echoed into this file profiling begins, and when a 566 zero is entered, profiling stops. A "functions" file is created in 567 the trace_stat directory; this file shows the list of functions that 568 have been hit and their counters. 569 570 If in doubt, say N. 571 572config BPF_KPROBE_OVERRIDE 573 bool "Enable BPF programs to override a kprobed function" 574 depends on BPF_EVENTS 575 depends on FUNCTION_ERROR_INJECTION 576 default n 577 help 578 Allows BPF to override the execution of a probed function and 579 set a different return value. This is used for error injection. 580 581config FTRACE_MCOUNT_RECORD 582 def_bool y 583 depends on DYNAMIC_FTRACE 584 depends on HAVE_FTRACE_MCOUNT_RECORD 585 586config FTRACE_SELFTEST 587 bool 588 589config FTRACE_STARTUP_TEST 590 bool "Perform a startup test on ftrace" 591 depends on GENERIC_TRACER 592 select FTRACE_SELFTEST 593 help 594 This option performs a series of startup tests on ftrace. On bootup 595 a series of tests are made to verify that the tracer is 596 functioning properly. It will do tests on all the configured 597 tracers of ftrace. 598 599config EVENT_TRACE_STARTUP_TEST 600 bool "Run selftest on trace events" 601 depends on FTRACE_STARTUP_TEST 602 default y 603 help 604 This option performs a test on all trace events in the system. 605 It basically just enables each event and runs some code that 606 will trigger events (not necessarily the event it enables) 607 This may take some time run as there are a lot of events. 608 609config EVENT_TRACE_TEST_SYSCALLS 610 bool "Run selftest on syscall events" 611 depends on EVENT_TRACE_STARTUP_TEST 612 help 613 This option will also enable testing every syscall event. 614 It only enables the event and disables it and runs various loads 615 with the event enabled. This adds a bit more time for kernel boot 616 up since it runs this on every system call defined. 617 618 TBD - enable a way to actually call the syscalls as we test their 619 events 620 621config MMIOTRACE 622 bool "Memory mapped IO tracing" 623 depends on HAVE_MMIOTRACE_SUPPORT && PCI 624 select GENERIC_TRACER 625 help 626 Mmiotrace traces Memory Mapped I/O access and is meant for 627 debugging and reverse engineering. It is called from the ioremap 628 implementation and works via page faults. Tracing is disabled by 629 default and can be enabled at run-time. 630 631 See Documentation/trace/mmiotrace.rst. 632 If you are not helping to develop drivers, say N. 633 634config TRACING_MAP 635 bool 636 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG 637 help 638 tracing_map is a special-purpose lock-free map for tracing, 639 separated out as a stand-alone facility in order to allow it 640 to be shared between multiple tracers. It isn't meant to be 641 generally used outside of that context, and is normally 642 selected by tracers that use it. 643 644config HIST_TRIGGERS 645 bool "Histogram triggers" 646 depends on ARCH_HAVE_NMI_SAFE_CMPXCHG 647 select TRACING_MAP 648 select TRACING 649 select DYNAMIC_EVENTS 650 default n 651 help 652 Hist triggers allow one or more arbitrary trace event fields 653 to be aggregated into hash tables and dumped to stdout by 654 reading a debugfs/tracefs file. They're useful for 655 gathering quick and dirty (though precise) summaries of 656 event activity as an initial guide for further investigation 657 using more advanced tools. 658 659 Inter-event tracing of quantities such as latencies is also 660 supported using hist triggers under this option. 661 662 See Documentation/trace/histogram.rst. 663 If in doubt, say N. 664 665config MMIOTRACE_TEST 666 tristate "Test module for mmiotrace" 667 depends on MMIOTRACE && m 668 help 669 This is a dumb module for testing mmiotrace. It is very dangerous 670 as it will write garbage to IO memory starting at a given address. 671 However, it should be safe to use on e.g. unused portion of VRAM. 672 673 Say N, unless you absolutely know what you are doing. 674 675config TRACEPOINT_BENCHMARK 676 bool "Add tracepoint that benchmarks tracepoints" 677 help 678 This option creates the tracepoint "benchmark:benchmark_event". 679 When the tracepoint is enabled, it kicks off a kernel thread that 680 goes into an infinite loop (calling cond_sched() to let other tasks 681 run), and calls the tracepoint. Each iteration will record the time 682 it took to write to the tracepoint and the next iteration that 683 data will be passed to the tracepoint itself. That is, the tracepoint 684 will report the time it took to do the previous tracepoint. 685 The string written to the tracepoint is a static string of 128 bytes 686 to keep the time the same. The initial string is simply a write of 687 "START". The second string records the cold cache time of the first 688 write which is not added to the rest of the calculations. 689 690 As it is a tight loop, it benchmarks as hot cache. That's fine because 691 we care most about hot paths that are probably in cache already. 692 693 An example of the output: 694 695 START 696 first=3672 [COLD CACHED] 697 last=632 first=3672 max=632 min=632 avg=316 std=446 std^2=199712 698 last=278 first=3672 max=632 min=278 avg=303 std=316 std^2=100337 699 last=277 first=3672 max=632 min=277 avg=296 std=258 std^2=67064 700 last=273 first=3672 max=632 min=273 avg=292 std=224 std^2=50411 701 last=273 first=3672 max=632 min=273 avg=288 std=200 std^2=40389 702 last=281 first=3672 max=632 min=273 avg=287 std=183 std^2=33666 703 704 705config RING_BUFFER_BENCHMARK 706 tristate "Ring buffer benchmark stress tester" 707 depends on RING_BUFFER 708 help 709 This option creates a test to stress the ring buffer and benchmark it. 710 It creates its own ring buffer such that it will not interfere with 711 any other users of the ring buffer (such as ftrace). It then creates 712 a producer and consumer that will run for 10 seconds and sleep for 713 10 seconds. Each interval it will print out the number of events 714 it recorded and give a rough estimate of how long each iteration took. 715 716 It does not disable interrupts or raise its priority, so it may be 717 affected by processes that are running. 718 719 If unsure, say N. 720 721config RING_BUFFER_STARTUP_TEST 722 bool "Ring buffer startup self test" 723 depends on RING_BUFFER 724 help 725 Run a simple self test on the ring buffer on boot up. Late in the 726 kernel boot sequence, the test will start that kicks off 727 a thread per cpu. Each thread will write various size events 728 into the ring buffer. Another thread is created to send IPIs 729 to each of the threads, where the IPI handler will also write 730 to the ring buffer, to test/stress the nesting ability. 731 If any anomalies are discovered, a warning will be displayed 732 and all ring buffers will be disabled. 733 734 The test runs for 10 seconds. This will slow your boot time 735 by at least 10 more seconds. 736 737 At the end of the test, statics and more checks are done. 738 It will output the stats of each per cpu buffer. What 739 was written, the sizes, what was read, what was lost, and 740 other similar details. 741 742 If unsure, say N 743 744config PREEMPTIRQ_DELAY_TEST 745 tristate "Preempt / IRQ disable delay thread to test latency tracers" 746 depends on m 747 help 748 Select this option to build a test module that can help test latency 749 tracers by executing a preempt or irq disable section with a user 750 configurable delay. The module busy waits for the duration of the 751 critical section. 752 753 For example, the following invocation forces a one-time irq-disabled 754 critical section for 500us: 755 modprobe preemptirq_delay_test test_mode=irq delay=500000 756 757 If unsure, say N 758 759config TRACE_EVAL_MAP_FILE 760 bool "Show eval mappings for trace events" 761 depends on TRACING 762 help 763 The "print fmt" of the trace events will show the enum/sizeof names 764 instead of their values. This can cause problems for user space tools 765 that use this string to parse the raw data as user space does not know 766 how to convert the string to its value. 767 768 To fix this, there's a special macro in the kernel that can be used 769 to convert an enum/sizeof into its value. If this macro is used, then 770 the print fmt strings will be converted to their values. 771 772 If something does not get converted properly, this option can be 773 used to show what enums/sizeof the kernel tried to convert. 774 775 This option is for debugging the conversions. A file is created 776 in the tracing directory called "eval_map" that will show the 777 names matched with their values and what trace event system they 778 belong too. 779 780 Normally, the mapping of the strings to values will be freed after 781 boot up or module load. With this option, they will not be freed, as 782 they are needed for the "eval_map" file. Enabling this option will 783 increase the memory footprint of the running kernel. 784 785 If unsure, say N 786 787config GCOV_PROFILE_FTRACE 788 bool "Enable GCOV profiling on ftrace subsystem" 789 depends on GCOV_KERNEL 790 help 791 Enable GCOV profiling on ftrace subsystem for checking 792 which functions/lines are tested. 793 794 If unsure, say N. 795 796 Note that on a kernel compiled with this config, ftrace will 797 run significantly slower. 798 799endif # FTRACE 800 801endif # TRACING_SUPPORT 802 803