| Kconfig (5661706efa200252d0e9fea02421b0a5857808c3) | Kconfig (2455f0e124d317dd08d337a7550a78a224d4ba41) |
|---|---|
| 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 --- 225 unchanged lines hidden (view full) --- 234 dynamically (will patch them out of the binary image and 235 replace them with a No-Op instruction) on boot up. During 236 compile time, a table is made of all the locations that ftrace 237 can function trace, and this table is linked into the kernel 238 image. When this is enabled, functions can be individually 239 enabled, and the functions not enabled will not affect 240 performance of the system. 241 | 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 --- 225 unchanged lines hidden (view full) --- 234 dynamically (will patch them out of the binary image and 235 replace them with a No-Op instruction) on boot up. During 236 compile time, a table is made of all the locations that ftrace 237 can function trace, and this table is linked into the kernel 238 image. When this is enabled, functions can be individually 239 enabled, and the functions not enabled will not affect 240 performance of the system. 241 |
| 242 See the files in /sys/kernel/debug/tracing: | 242 See the files in /sys/kernel/tracing: |
| 243 available_filter_functions 244 set_ftrace_filter 245 set_ftrace_notrace 246 247 This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but 248 otherwise has native performance as long as no tracing is active. 249 250config DYNAMIC_FTRACE_WITH_REGS --- 43 unchanged lines hidden (view full) --- 294config STACK_TRACER 295 bool "Trace max stack" 296 depends on HAVE_FUNCTION_TRACER 297 select FUNCTION_TRACER 298 select STACKTRACE 299 select KALLSYMS 300 help 301 This special tracer records the maximum stack footprint of the | 243 available_filter_functions 244 set_ftrace_filter 245 set_ftrace_notrace 246 247 This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but 248 otherwise has native performance as long as no tracing is active. 249 250config DYNAMIC_FTRACE_WITH_REGS --- 43 unchanged lines hidden (view full) --- 294config STACK_TRACER 295 bool "Trace max stack" 296 depends on HAVE_FUNCTION_TRACER 297 select FUNCTION_TRACER 298 select STACKTRACE 299 select KALLSYMS 300 help 301 This special tracer records the maximum stack footprint of the |
| 302 kernel and displays it in /sys/kernel/debug/tracing/stack_trace. | 302 kernel and displays it in /sys/kernel/tracing/stack_trace. |
| 303 304 This tracer works by hooking into every function call that the 305 kernel executes, and keeping a maximum stack depth value and 306 stack-trace saved. If this is configured with DYNAMIC_FTRACE 307 then it will not have any overhead while the stack tracer 308 is disabled. 309 310 To enable the stack tracer on bootup, pass in 'stacktrace' --- 23 unchanged lines hidden (view full) --- 334 help 335 This option measures the time spent in irqs-off critical 336 sections, with microsecond accuracy. 337 338 The default measurement method is a maximum search, which is 339 disabled by default and can be runtime (re-)started 340 via: 341 | 303 304 This tracer works by hooking into every function call that the 305 kernel executes, and keeping a maximum stack depth value and 306 stack-trace saved. If this is configured with DYNAMIC_FTRACE 307 then it will not have any overhead while the stack tracer 308 is disabled. 309 310 To enable the stack tracer on bootup, pass in 'stacktrace' --- 23 unchanged lines hidden (view full) --- 334 help 335 This option measures the time spent in irqs-off critical 336 sections, with microsecond accuracy. 337 338 The default measurement method is a maximum search, which is 339 disabled by default and can be runtime (re-)started 340 via: 341 |
| 342 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency | 342 echo 0 > /sys/kernel/tracing/tracing_max_latency |
| 343 344 (Note that kernel size and overhead increase with this option 345 enabled. This option and the preempt-off timing option can be 346 used together or separately.) 347 348config PREEMPT_TRACER 349 bool "Preemption-off Latency Tracer" 350 default n --- 7 unchanged lines hidden (view full) --- 358 help 359 This option measures the time spent in preemption-off critical 360 sections, with microsecond accuracy. 361 362 The default measurement method is a maximum search, which is 363 disabled by default and can be runtime (re-)started 364 via: 365 | 343 344 (Note that kernel size and overhead increase with this option 345 enabled. This option and the preempt-off timing option can be 346 used together or separately.) 347 348config PREEMPT_TRACER 349 bool "Preemption-off Latency Tracer" 350 default n --- 7 unchanged lines hidden (view full) --- 358 help 359 This option measures the time spent in preemption-off critical 360 sections, with microsecond accuracy. 361 362 The default measurement method is a maximum search, which is 363 disabled by default and can be runtime (re-)started 364 via: 365 |
| 366 echo 0 > /sys/kernel/debug/tracing/tracing_max_latency | 366 echo 0 > /sys/kernel/tracing/tracing_max_latency |
| 367 368 (Note that kernel size and overhead increase with this option 369 enabled. This option and the irqs-off timing option can be 370 used together or separately.) 371 372config SCHED_TRACER 373 bool "Scheduling Latency Tracer" 374 select GENERIC_TRACER --- 135 unchanged lines hidden (view full) --- 510 511config TRACER_SNAPSHOT 512 bool "Create a snapshot trace buffer" 513 select TRACER_MAX_TRACE 514 help 515 Allow tracing users to take snapshot of the current buffer using the 516 ftrace interface, e.g.: 517 | 367 368 (Note that kernel size and overhead increase with this option 369 enabled. This option and the irqs-off timing option can be 370 used together or separately.) 371 372config SCHED_TRACER 373 bool "Scheduling Latency Tracer" 374 select GENERIC_TRACER --- 135 unchanged lines hidden (view full) --- 510 511config TRACER_SNAPSHOT 512 bool "Create a snapshot trace buffer" 513 select TRACER_MAX_TRACE 514 help 515 Allow tracing users to take snapshot of the current buffer using the 516 ftrace interface, e.g.: 517 |
| 518 echo 1 > /sys/kernel/debug/tracing/snapshot | 518 echo 1 > /sys/kernel/tracing/snapshot |
| 519 cat snapshot 520 521config TRACER_SNAPSHOT_PER_CPU_SWAP 522 bool "Allow snapshot to swap per CPU" 523 depends on TRACER_SNAPSHOT 524 select RING_BUFFER_ALLOW_SWAP 525 help 526 Allow doing a snapshot of a single CPU buffer instead of a 527 full swap (all buffers). If this is set, then the following is 528 allowed: 529 | 519 cat snapshot 520 521config TRACER_SNAPSHOT_PER_CPU_SWAP 522 bool "Allow snapshot to swap per CPU" 523 depends on TRACER_SNAPSHOT 524 select RING_BUFFER_ALLOW_SWAP 525 help 526 Allow doing a snapshot of a single CPU buffer instead of a 527 full swap (all buffers). If this is set, then the following is 528 allowed: 529 |
| 530 echo 1 > /sys/kernel/debug/tracing/per_cpu/cpu2/snapshot | 530 echo 1 > /sys/kernel/tracing/per_cpu/cpu2/snapshot |
| 531 532 After which, only the tracing buffer for CPU 2 was swapped with 533 the main tracing buffer, and the other CPU buffers remain the same. 534 535 When this is enabled, this adds a little more overhead to the 536 trace recording, as it needs to add some checks to synchronize 537 recording with swaps. But this does not affect the performance 538 of the overall system. This is enabled by default when the preempt --- 30 unchanged lines hidden (view full) --- 569 570config PROFILE_ANNOTATED_BRANCHES 571 bool "Trace likely/unlikely profiler" 572 select TRACE_BRANCH_PROFILING 573 help 574 This tracer profiles all likely and unlikely macros 575 in the kernel. It will display the results in: 576 | 531 532 After which, only the tracing buffer for CPU 2 was swapped with 533 the main tracing buffer, and the other CPU buffers remain the same. 534 535 When this is enabled, this adds a little more overhead to the 536 trace recording, as it needs to add some checks to synchronize 537 recording with swaps. But this does not affect the performance 538 of the overall system. This is enabled by default when the preempt --- 30 unchanged lines hidden (view full) --- 569 570config PROFILE_ANNOTATED_BRANCHES 571 bool "Trace likely/unlikely profiler" 572 select TRACE_BRANCH_PROFILING 573 help 574 This tracer profiles all likely and unlikely macros 575 in the kernel. It will display the results in: 576 |
| 577 /sys/kernel/debug/tracing/trace_stat/branch_annotated | 577 /sys/kernel/tracing/trace_stat/branch_annotated |
| 578 579 Note: this will add a significant overhead; only turn this 580 on if you need to profile the system's use of these macros. 581 582config PROFILE_ALL_BRANCHES 583 bool "Profile all if conditionals" if !FORTIFY_SOURCE 584 select TRACE_BRANCH_PROFILING 585 help 586 This tracer profiles all branch conditions. Every if () 587 taken in the kernel is recorded whether it hit or miss. 588 The results will be displayed in: 589 | 578 579 Note: this will add a significant overhead; only turn this 580 on if you need to profile the system's use of these macros. 581 582config PROFILE_ALL_BRANCHES 583 bool "Profile all if conditionals" if !FORTIFY_SOURCE 584 select TRACE_BRANCH_PROFILING 585 help 586 This tracer profiles all branch conditions. Every if () 587 taken in the kernel is recorded whether it hit or miss. 588 The results will be displayed in: 589 |
| 590 /sys/kernel/debug/tracing/trace_stat/branch_all | 590 /sys/kernel/tracing/trace_stat/branch_all |
| 591 592 This option also enables the likely/unlikely profiler. 593 594 This configuration, when enabled, will impose a great overhead 595 on the system. This should only be enabled when the system 596 is to be analyzed in much detail. 597endchoice 598 --- 34 unchanged lines hidden (view full) --- 633 on a block device queue. For more information (and the userspace 634 support tools needed), fetch the blktrace tools from: 635 636 git://git.kernel.dk/blktrace.git 637 638 Tracing also is possible using the ftrace interface, e.g.: 639 640 echo 1 > /sys/block/sda/sda1/trace/enable | 591 592 This option also enables the likely/unlikely profiler. 593 594 This configuration, when enabled, will impose a great overhead 595 on the system. This should only be enabled when the system 596 is to be analyzed in much detail. 597endchoice 598 --- 34 unchanged lines hidden (view full) --- 633 on a block device queue. For more information (and the userspace 634 support tools needed), fetch the blktrace tools from: 635 636 git://git.kernel.dk/blktrace.git 637 638 Tracing also is possible using the ftrace interface, e.g.: 639 640 echo 1 > /sys/block/sda/sda1/trace/enable |
| 641 echo blk > /sys/kernel/debug/tracing/current_tracer 642 cat /sys/kernel/debug/tracing/trace_pipe | 641 echo blk > /sys/kernel/tracing/current_tracer 642 cat /sys/kernel/tracing/trace_pipe |
| 643 644 If unsure, say N. 645 646config KPROBE_EVENTS 647 depends on KPROBES 648 depends on HAVE_REGS_AND_STACK_ACCESS_API 649 bool "Enable kprobes-based dynamic events" 650 select TRACING --- 476 unchanged lines hidden --- | 643 644 If unsure, say N. 645 646config KPROBE_EVENTS 647 depends on KPROBES 648 depends on HAVE_REGS_AND_STACK_ACCESS_API 649 bool "Enable kprobes-based dynamic events" 650 select TRACING --- 476 unchanged lines hidden --- |