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1#
2# Architectures that offer an FTRACE implementation should select HAVE_FTRACE:
3#
4config HAVE_FTRACE
5 bool
6
7config HAVE_DYNAMIC_FTRACE
8 bool
9
10config TRACER_MAX_TRACE
11 bool
12
13config TRACING
14 bool
15 select DEBUG_FS
16 select STACKTRACE
17
18config FTRACE
19 bool "Kernel Function Tracer"
20 depends on HAVE_FTRACE
21 select FRAME_POINTER
22 select TRACING
23 select CONTEXT_SWITCH_TRACER
24 help
25 Enable the kernel to trace every kernel function. This is done
26 by using a compiler feature to insert a small, 5-byte No-Operation
27 instruction to the beginning of every kernel function, which NOP
28 sequence is then dynamically patched into a tracer call when
29 tracing is enabled by the administrator. If it's runtime disabled
30 (the bootup default), then the overhead of the instructions is very
31 small and not measurable even in micro-benchmarks.
32
33config IRQSOFF_TRACER
34 bool "Interrupts-off Latency Tracer"
35 default n
36 depends on TRACE_IRQFLAGS_SUPPORT
37 depends on GENERIC_TIME
38 depends on HAVE_FTRACE
39 select TRACE_IRQFLAGS
40 select TRACING
41 select TRACER_MAX_TRACE
42 help
43 This option measures the time spent in irqs-off critical
44 sections, with microsecond accuracy.
45
46 The default measurement method is a maximum search, which is
47 disabled by default and can be runtime (re-)started
48 via:
49
50 echo 0 > /debugfs/tracing/tracing_max_latency
51
52 (Note that kernel size and overhead increases with this option
53 enabled. This option and the preempt-off timing option can be
54 used together or separately.)
55
56config PREEMPT_TRACER
57 bool "Preemption-off Latency Tracer"
58 default n
59 depends on GENERIC_TIME
60 depends on PREEMPT
61 depends on HAVE_FTRACE
62 select TRACING
63 select TRACER_MAX_TRACE
64 help
65 This option measures the time spent in preemption off critical
66 sections, with microsecond accuracy.
67
68 The default measurement method is a maximum search, which is
69 disabled by default and can be runtime (re-)started
70 via:
71
72 echo 0 > /debugfs/tracing/tracing_max_latency
73
74 (Note that kernel size and overhead increases with this option
75 enabled. This option and the irqs-off timing option can be
76 used together or separately.)
77
78config SCHED_TRACER
79 bool "Scheduling Latency Tracer"
80 depends on HAVE_FTRACE
81 select TRACING
82 select CONTEXT_SWITCH_TRACER
83 select TRACER_MAX_TRACE
84 help
85 This tracer tracks the latency of the highest priority task
86 to be scheduled in, starting from the point it has woken up.
87
88config CONTEXT_SWITCH_TRACER
89 bool "Trace process context switches"
90 depends on HAVE_FTRACE
91 select TRACING
92 select MARKERS
93 help
94 This tracer gets called from the context switch and records
95 all switching of tasks.
96
97config DYNAMIC_FTRACE
98 bool "enable/disable ftrace tracepoints dynamically"
99 depends on FTRACE
100 depends on HAVE_DYNAMIC_FTRACE
101 default y
102 help
103 This option will modify all the calls to ftrace dynamically
104 (will patch them out of the binary image and replaces them
105 with a No-Op instruction) as they are called. A table is
106 created to dynamically enable them again.
107
108 This way a CONFIG_FTRACE kernel is slightly larger, but otherwise
109 has native performance as long as no tracing is active.
110
111 The changes to the code are done by a kernel thread that
112 wakes up once a second and checks to see if any ftrace calls
113 were made. If so, it runs stop_machine (stops all CPUS)
114 and modifies the code to jump over the call to ftrace.
115
116config FTRACE_SELFTEST
117 bool
118
119config FTRACE_STARTUP_TEST
120 bool "Perform a startup test on ftrace"
121 depends on TRACING
122 select FTRACE_SELFTEST
123 help
124 This option performs a series of startup tests on ftrace. On bootup
125 a series of tests are made to verify that the tracer is
126 functioning properly. It will do tests on all the configured
127 tracers of ftrace.