2 # Architectures that offer an FTRACE implementation should select HAVE_FTRACE:
12 config HAVE_DYNAMIC_FTRACE
15 config HAVE_FTRACE_MCOUNT_RECORD
18 config TRACER_MAX_TRACE
32 bool "Kernel Function Tracer"
33 depends on HAVE_FTRACE
34 depends on DEBUG_KERNEL
37 select CONTEXT_SWITCH_TRACER
39 Enable the kernel to trace every kernel function. This is done
40 by using a compiler feature to insert a small, 5-byte No-Operation
41 instruction to the beginning of every kernel function, which NOP
42 sequence is then dynamically patched into a tracer call when
43 tracing is enabled by the administrator. If it's runtime disabled
44 (the bootup default), then the overhead of the instructions is very
45 small and not measurable even in micro-benchmarks.
48 bool "Interrupts-off Latency Tracer"
50 depends on TRACE_IRQFLAGS_SUPPORT
51 depends on GENERIC_TIME
52 depends on HAVE_FTRACE
53 depends on DEBUG_KERNEL
56 select TRACER_MAX_TRACE
58 This option measures the time spent in irqs-off critical
59 sections, with microsecond accuracy.
61 The default measurement method is a maximum search, which is
62 disabled by default and can be runtime (re-)started
65 echo 0 > /debugfs/tracing/tracing_max_latency
67 (Note that kernel size and overhead increases with this option
68 enabled. This option and the preempt-off timing option can be
69 used together or separately.)
72 bool "Preemption-off Latency Tracer"
74 depends on GENERIC_TIME
76 depends on HAVE_FTRACE
77 depends on DEBUG_KERNEL
79 select TRACER_MAX_TRACE
81 This option measures the time spent in preemption off critical
82 sections, with microsecond accuracy.
84 The default measurement method is a maximum search, which is
85 disabled by default and can be runtime (re-)started
88 echo 0 > /debugfs/tracing/tracing_max_latency
90 (Note that kernel size and overhead increases with this option
91 enabled. This option and the irqs-off timing option can be
92 used together or separately.)
99 This tracer provides the trace needed by the 'Sysprof' userspace
103 bool "Scheduling Latency Tracer"
104 depends on HAVE_FTRACE
105 depends on DEBUG_KERNEL
107 select CONTEXT_SWITCH_TRACER
108 select TRACER_MAX_TRACE
110 This tracer tracks the latency of the highest priority task
111 to be scheduled in, starting from the point it has woken up.
113 config CONTEXT_SWITCH_TRACER
114 bool "Trace process context switches"
115 depends on HAVE_FTRACE
116 depends on DEBUG_KERNEL
120 This tracer gets called from the context switch and records
121 all switching of tasks.
124 bool "Trace boot initcalls"
125 depends on HAVE_FTRACE
126 depends on DEBUG_KERNEL
129 This tracer helps developers to optimize boot times: it records
130 the timings of the initcalls. Its aim is to be parsed by the
131 /scripts/bootgraph.pl tool to produce pretty graphics about
132 boot inefficiencies, giving a visual representation of the
133 delays during initcalls. Note that tracers self tests can't
134 be enabled if this tracer is selected since only one tracer
135 should touch the tracing buffer at a time.
138 bool "Trace max stack"
139 depends on HAVE_FTRACE
140 depends on DEBUG_KERNEL
144 This special tracer records the maximum stack footprint of the
145 kernel and displays it in debugfs/tracing/stack_trace.
147 This tracer works by hooking into every function call that the
148 kernel executes, and keeping a maximum stack depth value and
149 stack-trace saved. Because this logic has to execute in every
150 kernel function, all the time, this option can slow down the
151 kernel measurably and is generally intended for kernel
156 config DYNAMIC_FTRACE
157 bool "enable/disable ftrace tracepoints dynamically"
159 depends on HAVE_DYNAMIC_FTRACE
160 depends on DEBUG_KERNEL
163 This option will modify all the calls to ftrace dynamically
164 (will patch them out of the binary image and replaces them
165 with a No-Op instruction) as they are called. A table is
166 created to dynamically enable them again.
168 This way a CONFIG_FTRACE kernel is slightly larger, but otherwise
169 has native performance as long as no tracing is active.
171 The changes to the code are done by a kernel thread that
172 wakes up once a second and checks to see if any ftrace calls
173 were made. If so, it runs stop_machine (stops all CPUS)
174 and modifies the code to jump over the call to ftrace.
176 config FTRACE_MCOUNT_RECORD
178 depends on DYNAMIC_FTRACE
179 depends on HAVE_FTRACE_MCOUNT_RECORD
181 config FTRACE_SELFTEST
184 config FTRACE_STARTUP_TEST
185 bool "Perform a startup test on ftrace"
186 depends on TRACING && DEBUG_KERNEL && !BOOT_TRACER
187 select FTRACE_SELFTEST
189 This option performs a series of startup tests on ftrace. On bootup
190 a series of tests are made to verify that the tracer is
191 functioning properly. It will do tests on all the configured