C version of recordmcount available?
Provides old power event types: C-state/idle accounting events: power:power_start power:power_end and old cpufreq accounting event: power:power_frequency This is for userspace compatibility and will vanish after 5 kernel iterations, namely 2.6.41.
Allow the use of ring_buffer_swap_cpu. Adds a very slight overhead to tracing when enabled.
Enable the kernel tracing infrastructure.
Enable the kernel to trace every kernel function. This is done by using a compiler feature to insert a small, 5-byte No-Operation instruction at the beginning of every kernel function, which NOP sequence is then dynamically patched into a tracer call when tracing is enabled by the administrator. If it's runtime disabled (the bootup default), then the overhead of the instructions is very small and not measurable even in micro-benchmarks.
Enable the kernel to trace a function at both its return and its entry. Its first purpose is to trace the duration of functions and draw a call graph for each thread with some information like the return value. This is done by setting the current return address on the current task structure into a stack of calls.
This option measures the time spent in irqs-off critical sections, with microsecond accuracy. The default measurement method is a maximum search, which is disabled by default and can be runtime (re-)started via: echo 0 > /sys/kernel/debug/tracing/tracing_max_latency (Note that kernel size and overhead increase with this option enabled. This option and the preempt-off timing option can be used together or separately.)
This option measures the time spent in preemption-off critical sections, with microsecond accuracy. The default measurement method is a maximum search, which is disabled by default and can be runtime (re-)started via: echo 0 > /sys/kernel/debug/tracing/tracing_max_latency (Note that kernel size and overhead increase with this option enabled. This option and the irqs-off timing option can be used together or separately.)
This tracer tracks the latency of the highest priority task to be scheduled in, starting from the point it has woken up.
This tracer hooks to various trace points in the kernel, allowing the user to pick and choose which trace point they want to trace. It also includes the sched_switch tracer plugin.
Basic tracer to catch the syscall entry and exit events.
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".
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.
This tracer profiles all the the likely and unlikely macros in the kernel. It will display the results in: /sys/kernel/debug/tracing/trace_stat/branch_annotated Note: this will add a significant overhead; only turn this on if you need to profile the system's use of these macros.
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/trace_stat/branch_all 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.
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.
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.
This special tracer records the maximum stack footprint of the kernel and displays it in /sys/kernel/debug/tracing/stack_trace. This tracer works by hooking into every function call that the kernel executes, and keeping a maximum stack depth value and stack-trace saved. If this is configured with DYNAMIC_FTRACE then it will not have any overhead while the stack tracer is disabled. To enable the stack tracer on bootup, pass in 'stacktrace' on the kernel command line. The stack tracer can also be enabled or disabled via the sysctl kernel.stack_tracer_enabled Say N if unsure.
Say Y here if you want to be able to trace the block layer actions on a given queue. Tracing allows you to see any traffic happening on a block device queue. For more information (and the userspace support tools needed), fetch the blktrace tools from: git://git.kernel.dk/blktrace.git Tracing also is possible using the ftrace interface, e.g.: echo 1 > /sys/block/sda/sda1/trace/enable echo blk > /sys/kernel/debug/tracing/current_tracer cat /sys/kernel/debug/tracing/trace_pipe If unsure, say N.
This allows the user to add tracing events (similar to tracepoints) on the fly via the ftrace interface. See Documentation/trace/kprobetrace.txt for more details. Those events can be inserted wherever kprobes can probe, and record various register and memory values. This option is also required by perf-probe subcommand of perf tools. If you want to use perf tools, this option is strongly recommended.
This option will modify all the calls to ftrace dynamically (will patch them out of the binary image and replace them with a No-Op instruction) as they are called. A table is created to dynamically enable them again. This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but otherwise has native performance as long as no tracing is active. The changes to the code are done by a kernel thread that wakes up once a second and checks to see if any ftrace calls were made. If so, it runs stop_machine (stops all CPUS) and modifies the code to jump over the call to ftrace.
This option enables the kernel function profiler. A file is created in debugfs called function_profile_enabled which defaults to zero. When a 1 is echoed into this file profiling begins, and when a zero is entered, profiling stops. A "functions" file is created in the trace_stats directory; this file shows the list of functions that have been hit and their counters. If in doubt, say N.
This option performs a series of startup tests on ftrace. On bootup a series of tests are made to verify that the tracer is functioning properly. It will do tests on all the configured tracers of ftrace.
This option will also enable testing every syscall event. It only enables the event and disables it and runs various loads with the event enabled. This adds a bit more time for kernel boot up since it runs this on every system call defined. TBD - enable a way to actually call the syscalls as we test their events
Mmiotrace traces Memory Mapped I/O access and is meant for debugging and reverse engineering. It is called from the ioremap implementation and works via page faults. Tracing is disabled by default and can be enabled at run-time. See Documentation/trace/mmiotrace.txt. If you are not helping to develop drivers, say N.
This is a dumb module for testing mmiotrace. It is very dangerous as it will write garbage to IO memory starting at a given address. However, it should be safe to use on e.g. unused portion of VRAM. Say N, unless you absolutely know what you are doing.
This option creates a test to stress the ring buffer and benchmark it. It creates its own ring buffer such that it will not interfere with any other users of the ring buffer (such as ftrace). It then creates a producer and consumer that will run for 10 seconds and sleep for 10 seconds. Each interval it will print out the number of events it recorded and give a rough estimate of how long each iteration took. It does not disable interrupts or raise its priority, so it may be affected by processes that are running. If unsure, say N.