2 # Architectures that offer an FUNCTION_TRACER implementation should
3 # select HAVE_FUNCTION_TRACER:
6 config USER_STACKTRACE_SUPPORT
12 config HAVE_FTRACE_NMI_ENTER
15 config HAVE_FUNCTION_TRACER
18 config HAVE_FUNCTION_GRAPH_TRACER
21 config HAVE_FUNCTION_TRACE_MCOUNT_TEST
24 This gets selected when the arch tests the function_trace_stop
25 variable at the mcount call site. Otherwise, this variable
26 is tested by the called function.
28 config HAVE_DYNAMIC_FTRACE
31 config HAVE_FTRACE_MCOUNT_RECORD
34 config HAVE_HW_BRANCH_TRACER
37 config TRACER_MAX_TRACE
43 config FTRACE_NMI_ENTER
45 depends on HAVE_FTRACE_NMI_ENTER
52 select STACKTRACE if STACKTRACE_SUPPORT
58 config FUNCTION_TRACER
59 bool "Kernel Function Tracer"
60 depends on HAVE_FUNCTION_TRACER
61 depends on DEBUG_KERNEL
65 select CONTEXT_SWITCH_TRACER
67 Enable the kernel to trace every kernel function. This is done
68 by using a compiler feature to insert a small, 5-byte No-Operation
69 instruction to the beginning of every kernel function, which NOP
70 sequence is then dynamically patched into a tracer call when
71 tracing is enabled by the administrator. If it's runtime disabled
72 (the bootup default), then the overhead of the instructions is very
73 small and not measurable even in micro-benchmarks.
75 config FUNCTION_GRAPH_TRACER
76 bool "Kernel Function Graph Tracer"
77 depends on HAVE_FUNCTION_GRAPH_TRACER
78 depends on FUNCTION_TRACER
81 Enable the kernel to trace a function at both its return
83 It's first purpose is to trace the duration of functions and
84 draw a call graph for each thread with some informations like
86 This is done by setting the current return address on the current
87 task structure into a stack of calls.
90 bool "Interrupts-off Latency Tracer"
92 depends on TRACE_IRQFLAGS_SUPPORT
93 depends on GENERIC_TIME
94 depends on DEBUG_KERNEL
97 select TRACER_MAX_TRACE
99 This option measures the time spent in irqs-off critical
100 sections, with microsecond accuracy.
102 The default measurement method is a maximum search, which is
103 disabled by default and can be runtime (re-)started
106 echo 0 > /debugfs/tracing/tracing_max_latency
108 (Note that kernel size and overhead increases with this option
109 enabled. This option and the preempt-off timing option can be
110 used together or separately.)
112 config PREEMPT_TRACER
113 bool "Preemption-off Latency Tracer"
115 depends on GENERIC_TIME
117 depends on DEBUG_KERNEL
119 select TRACER_MAX_TRACE
121 This option measures the time spent in preemption off critical
122 sections, with microsecond accuracy.
124 The default measurement method is a maximum search, which is
125 disabled by default and can be runtime (re-)started
128 echo 0 > /debugfs/tracing/tracing_max_latency
130 (Note that kernel size and overhead increases with this option
131 enabled. This option and the irqs-off timing option can be
132 used together or separately.)
134 config SYSPROF_TRACER
135 bool "Sysprof Tracer"
138 select CONTEXT_SWITCH_TRACER
140 This tracer provides the trace needed by the 'Sysprof' userspace
144 bool "Scheduling Latency Tracer"
145 depends on DEBUG_KERNEL
147 select CONTEXT_SWITCH_TRACER
148 select TRACER_MAX_TRACE
150 This tracer tracks the latency of the highest priority task
151 to be scheduled in, starting from the point it has woken up.
153 config CONTEXT_SWITCH_TRACER
154 bool "Trace process context switches"
155 depends on DEBUG_KERNEL
159 This tracer gets called from the context switch and records
160 all switching of tasks.
163 bool "Trace boot initcalls"
164 depends on DEBUG_KERNEL
166 select CONTEXT_SWITCH_TRACER
168 This tracer helps developers to optimize boot times: it records
169 the timings of the initcalls and traces key events and the identity
170 of tasks that can cause boot delays, such as context-switches.
172 Its aim is to be parsed by the /scripts/bootgraph.pl tool to
173 produce pretty graphics about boot inefficiencies, giving a visual
174 representation of the delays during initcalls - but the raw
175 /debug/tracing/trace text output is readable too.
177 You must pass in ftrace=initcall to the kernel command line
178 to enable this on bootup.
180 config TRACE_BRANCH_PROFILING
181 bool "Trace likely/unlikely profiler"
182 depends on DEBUG_KERNEL
185 This tracer profiles all the the likely and unlikely macros
186 in the kernel. It will display the results in:
188 /debugfs/tracing/profile_annotated_branch
190 Note: this will add a significant overhead, only turn this
191 on if you need to profile the system's use of these macros.
195 config PROFILE_ALL_BRANCHES
196 bool "Profile all if conditionals"
197 depends on TRACE_BRANCH_PROFILING
199 This tracer profiles all branch conditions. Every if ()
200 taken in the kernel is recorded whether it hit or miss.
201 The results will be displayed in:
203 /debugfs/tracing/profile_branch
205 This configuration, when enabled, will impose a great overhead
206 on the system. This should only be enabled when the system
211 config TRACING_BRANCHES
214 Selected by tracers that will trace the likely and unlikely
215 conditions. This prevents the tracers themselves from being
216 profiled. Profiling the tracing infrastructure can only happen
217 when the likelys and unlikelys are not being traced.
220 bool "Trace likely/unlikely instances"
221 depends on TRACE_BRANCH_PROFILING
222 select TRACING_BRANCHES
224 This traces the events of likely and unlikely condition
225 calls in the kernel. The difference between this and the
226 "Trace likely/unlikely profiler" is that this is not a
227 histogram of the callers, but actually places the calling
228 events into a running trace buffer to see when and where the
229 events happened, as well as their results.
234 bool "Trace power consumption behavior"
235 depends on DEBUG_KERNEL
239 This tracer helps developers to analyze and optimize the kernels
240 power management decisions, specifically the C-state and P-state
245 bool "Trace max stack"
246 depends on HAVE_FUNCTION_TRACER
247 depends on DEBUG_KERNEL
248 select FUNCTION_TRACER
252 This special tracer records the maximum stack footprint of the
253 kernel and displays it in debugfs/tracing/stack_trace.
255 This tracer works by hooking into every function call that the
256 kernel executes, and keeping a maximum stack depth value and
257 stack-trace saved. If this is configured with DYNAMIC_FTRACE
258 then it will not have any overhead while the stack tracer
261 To enable the stack tracer on bootup, pass in 'stacktrace'
262 on the kernel command line.
264 The stack tracer can also be enabled or disabled via the
265 sysctl kernel.stack_tracer_enabled
269 config HW_BRANCH_TRACER
270 depends on HAVE_HW_BRANCH_TRACER
271 bool "Trace hw branches"
274 This tracer records all branches on the system in a circular
275 buffer giving access to the last N branches for each cpu.
278 bool "Trace SLAB allocations"
281 kmemtrace provides tracing for slab allocator functions, such as
282 kmalloc, kfree, kmem_cache_alloc, kmem_cache_free etc.. Collected
283 data is then fed to the userspace application in order to analyse
284 allocation hotspots, internal fragmentation and so on, making it
285 possible to see how well an allocator performs, as well as debug
286 and profile kernel code.
288 This requires an userspace application to use. See
289 Documentation/vm/kmemtrace.txt for more information.
291 Saying Y will make the kernel somewhat larger and slower. However,
292 if you disable kmemtrace at run-time or boot-time, the performance
293 impact is minimal (depending on the arch the kernel is built for).
297 config WORKQUEUE_TRACER
298 bool "Trace workqueues"
301 The workqueue tracer provides some statistical informations
302 about each cpu workqueue thread such as the number of the
303 works inserted and executed since their creation. It can help
304 to evaluate the amount of work each of them have to perform.
305 For example it can help a developer to decide whether he should
306 choose a per cpu workqueue instead of a singlethreaded one.
308 config BLK_DEV_IO_TRACE
309 bool "Support for tracing block io actions"
318 Say Y here if you want to be able to trace the block layer actions
319 on a given queue. Tracing allows you to see any traffic happening
320 on a block device queue. For more information (and the userspace
321 support tools needed), fetch the blktrace tools from:
323 git://git.kernel.dk/blktrace.git
325 Tracing also is possible using the ftrace interface, e.g.:
327 echo 1 > /sys/block/sda/sda1/trace/enable
328 echo blk > /sys/kernel/debug/tracing/current_tracer
329 cat /sys/kernel/debug/tracing/trace_pipe
333 config DYNAMIC_FTRACE
334 bool "enable/disable ftrace tracepoints dynamically"
335 depends on FUNCTION_TRACER
336 depends on HAVE_DYNAMIC_FTRACE
337 depends on DEBUG_KERNEL
340 This option will modify all the calls to ftrace dynamically
341 (will patch them out of the binary image and replaces them
342 with a No-Op instruction) as they are called. A table is
343 created to dynamically enable them again.
345 This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but otherwise
346 has native performance as long as no tracing is active.
348 The changes to the code are done by a kernel thread that
349 wakes up once a second and checks to see if any ftrace calls
350 were made. If so, it runs stop_machine (stops all CPUS)
351 and modifies the code to jump over the call to ftrace.
353 config FTRACE_MCOUNT_RECORD
355 depends on DYNAMIC_FTRACE
356 depends on HAVE_FTRACE_MCOUNT_RECORD
358 config FTRACE_SELFTEST
361 config FTRACE_STARTUP_TEST
362 bool "Perform a startup test on ftrace"
363 depends on TRACING && DEBUG_KERNEL
364 select FTRACE_SELFTEST
366 This option performs a series of startup tests on ftrace. On bootup
367 a series of tests are made to verify that the tracer is
368 functioning properly. It will do tests on all the configured
372 bool "Memory mapped IO tracing"
373 depends on HAVE_MMIOTRACE_SUPPORT && DEBUG_KERNEL && PCI
376 Mmiotrace traces Memory Mapped I/O access and is meant for
377 debugging and reverse engineering. It is called from the ioremap
378 implementation and works via page faults. Tracing is disabled by
379 default and can be enabled at run-time.
381 See Documentation/tracers/mmiotrace.txt.
382 If you are not helping to develop drivers, say N.
384 config MMIOTRACE_TEST
385 tristate "Test module for mmiotrace"
386 depends on MMIOTRACE && m
388 This is a dumb module for testing mmiotrace. It is very dangerous
389 as it will write garbage to IO memory starting at a given address.
390 However, it should be safe to use on e.g. unused portion of VRAM.
392 Say N, unless you absolutely know what you are doing.