+ the timings of the initcalls and traces key events and the identity
+ of tasks that can cause boot delays, such as context-switches.
+
+ Its aim is to be parsed by the scripts/bootgraph.pl tool to
+ produce pretty graphics about boot inefficiencies, giving a visual
+ representation of the delays during initcalls - but the raw
+ /debug/tracing/trace text output is readable too.
+
+ You must pass in initcall_debug and ftrace=initcall to the kernel
+ command line to enable this on bootup.
+
+config TRACE_BRANCH_PROFILING
+ bool
+ select GENERIC_TRACER
+
+choice
+ prompt "Branch Profiling"
+ default BRANCH_PROFILE_NONE
+ help
+ The branch profiling is a software profiler. It will add hooks
+ into the C conditionals to test which path a branch takes.
+
+ The likely/unlikely profiler only looks at the conditions that
+ are annotated with a likely or unlikely macro.
+
+ The "all branch" profiler will profile every if-statement in the
+ kernel. This profiler will also enable the likely/unlikely
+ profiler.
+
+ Either of the above profilers adds a bit of overhead to the system.
+ If unsure, choose "No branch profiling".
+
+config BRANCH_PROFILE_NONE
+ bool "No branch profiling"
+ help
+ No branch profiling. Branch profiling adds a bit of overhead.
+ Only enable it if you want to analyse the branching behavior.
+ Otherwise keep it disabled.
+
+config PROFILE_ANNOTATED_BRANCHES
+ bool "Trace likely/unlikely profiler"
+ select TRACE_BRANCH_PROFILING
+ help
+ This tracer profiles all the the likely and unlikely macros
+ in the kernel. It will display the results in:
+
+ /sys/kernel/debug/tracing/profile_annotated_branch
+
+ Note: this will add a significant overhead; only turn this
+ on if you need to profile the system's use of these macros.
+
+config PROFILE_ALL_BRANCHES
+ bool "Profile all if conditionals"
+ select TRACE_BRANCH_PROFILING
+ help
+ This tracer profiles all branch conditions. Every if ()
+ taken in the kernel is recorded whether it hit or miss.
+ The results will be displayed in:
+
+ /sys/kernel/debug/tracing/profile_branch
+
+ This option also enables the likely/unlikely profiler.
+
+ This configuration, when enabled, will impose a great overhead
+ on the system. This should only be enabled when the system
+ is to be analyzed in much detail.
+endchoice
+
+config TRACING_BRANCHES
+ bool
+ help
+ Selected by tracers that will trace the likely and unlikely
+ conditions. This prevents the tracers themselves from being
+ profiled. Profiling the tracing infrastructure can only happen
+ when the likelys and unlikelys are not being traced.
+
+config BRANCH_TRACER
+ bool "Trace likely/unlikely instances"
+ depends on TRACE_BRANCH_PROFILING
+ select TRACING_BRANCHES
+ help
+ This traces the events of likely and unlikely condition
+ calls in the kernel. The difference between this and the
+ "Trace likely/unlikely profiler" is that this is not a
+ histogram of the callers, but actually places the calling
+ events into a running trace buffer to see when and where the
+ events happened, as well as their results.
+
+ Say N if unsure.
+
+config KSYM_TRACER
+ bool "Trace read and write access on kernel memory locations"
+ depends on HAVE_HW_BREAKPOINT
+ select TRACING
+ help
+ This tracer helps find read and write operations on any given kernel
+ symbol i.e. /proc/kallsyms.
+
+config PROFILE_KSYM_TRACER
+ bool "Profile all kernel memory accesses on 'watched' variables"
+ depends on KSYM_TRACER
+ help
+ This tracer profiles kernel accesses on variables watched through the
+ ksym tracer ftrace plugin. Depending upon the hardware, all read
+ and write operations on kernel variables can be monitored for
+ accesses.
+
+ The results will be displayed in:
+ /debugfs/tracing/profile_ksym
+
+ Say N if unsure.