| # |
| # Architectures that offer an FUNCTION_TRACER implementation should |
| # select HAVE_FUNCTION_TRACER: |
| # |
| |
| config USER_STACKTRACE_SUPPORT |
| bool |
| |
| config NOP_TRACER |
| bool |
| |
| config HAVE_FUNCTION_TRACER |
| bool |
| |
| config HAVE_FUNCTION_RET_TRACER |
| bool |
| |
| config HAVE_FUNCTION_TRACE_MCOUNT_TEST |
| bool |
| help |
| This gets selected when the arch tests the function_trace_stop |
| variable at the mcount call site. Otherwise, this variable |
| is tested by the called function. |
| |
| config HAVE_DYNAMIC_FTRACE |
| bool |
| |
| config HAVE_FTRACE_MCOUNT_RECORD |
| bool |
| |
| config HAVE_HW_BRANCH_TRACER |
| bool |
| |
| config TRACER_MAX_TRACE |
| bool |
| |
| config RING_BUFFER |
| bool |
| |
| config TRACING |
| bool |
| select DEBUG_FS |
| select RING_BUFFER |
| select STACKTRACE if STACKTRACE_SUPPORT |
| select TRACEPOINTS |
| select NOP_TRACER |
| |
| menu "Tracers" |
| |
| config FUNCTION_TRACER |
| bool "Kernel Function Tracer" |
| depends on HAVE_FUNCTION_TRACER |
| depends on DEBUG_KERNEL |
| select FRAME_POINTER |
| select TRACING |
| select CONTEXT_SWITCH_TRACER |
| help |
| 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 to 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. |
| |
| config FUNCTION_RET_TRACER |
| bool "Kernel Function return Tracer" |
| depends on HAVE_FUNCTION_RET_TRACER |
| depends on FUNCTION_TRACER |
| help |
| Enable the kernel to trace a function at its return. |
| It's first purpose is to trace the duration of functions. |
| This is done by setting the current return address on the thread |
| info structure of the current task. |
| |
| config IRQSOFF_TRACER |
| bool "Interrupts-off Latency Tracer" |
| default n |
| depends on TRACE_IRQFLAGS_SUPPORT |
| depends on GENERIC_TIME |
| depends on DEBUG_KERNEL |
| select TRACE_IRQFLAGS |
| select TRACING |
| select TRACER_MAX_TRACE |
| help |
| 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 > /debugfs/tracing/tracing_max_latency |
| |
| (Note that kernel size and overhead increases with this option |
| enabled. This option and the preempt-off timing option can be |
| used together or separately.) |
| |
| config PREEMPT_TRACER |
| bool "Preemption-off Latency Tracer" |
| default n |
| depends on GENERIC_TIME |
| depends on PREEMPT |
| depends on DEBUG_KERNEL |
| select TRACING |
| select TRACER_MAX_TRACE |
| help |
| 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 > /debugfs/tracing/tracing_max_latency |
| |
| (Note that kernel size and overhead increases with this option |
| enabled. This option and the irqs-off timing option can be |
| used together or separately.) |
| |
| config SYSPROF_TRACER |
| bool "Sysprof Tracer" |
| depends on X86 |
| select TRACING |
| help |
| This tracer provides the trace needed by the 'Sysprof' userspace |
| tool. |
| |
| config SCHED_TRACER |
| bool "Scheduling Latency Tracer" |
| depends on DEBUG_KERNEL |
| select TRACING |
| select CONTEXT_SWITCH_TRACER |
| select TRACER_MAX_TRACE |
| help |
| This tracer tracks the latency of the highest priority task |
| to be scheduled in, starting from the point it has woken up. |
| |
| config CONTEXT_SWITCH_TRACER |
| bool "Trace process context switches" |
| depends on DEBUG_KERNEL |
| select TRACING |
| select MARKERS |
| help |
| This tracer gets called from the context switch and records |
| all switching of tasks. |
| |
| config BOOT_TRACER |
| bool "Trace boot initcalls" |
| depends on DEBUG_KERNEL |
| select TRACING |
| select CONTEXT_SWITCH_TRACER |
| help |
| This tracer helps developers to optimize boot times: it records |
| 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. |
| |
| ( Note that tracing self tests can't be enabled if this tracer is |
| selected, because the self-tests are an initcall as well and that |
| would invalidate the boot trace. ) |
| |
| config TRACE_BRANCH_PROFILING |
| bool "Trace likely/unlikely profiler" |
| depends on DEBUG_KERNEL |
| select TRACING |
| help |
| This tracer profiles all the the likely and unlikely macros |
| in the kernel. It will display the results in: |
| |
| /debugfs/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. |
| |
| Say N if unsure. |
| |
| config PROFILE_ALL_BRANCHES |
| bool "Profile all if conditionals" |
| depends on 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: |
| |
| /debugfs/tracing/profile_branch |
| |
| This configuration, when enabled, will impose a great overhead |
| on the system. This should only be enabled when the system |
| is to be analyzed |
| |
| Say N if unsure. |
| |
| 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 STACK_TRACER |
| bool "Trace max stack" |
| depends on HAVE_FUNCTION_TRACER |
| depends on DEBUG_KERNEL |
| select FUNCTION_TRACER |
| select STACKTRACE |
| help |
| This special tracer records the maximum stack footprint of the |
| kernel and displays it in debugfs/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. Because this logic has to execute in every |
| kernel function, all the time, this option can slow down the |
| kernel measurably and is generally intended for kernel |
| developers only. |
| |
| Say N if unsure. |
| |
| config BTS_TRACER |
| depends on HAVE_HW_BRANCH_TRACER |
| bool "Trace branches" |
| select TRACING |
| help |
| This tracer records all branches on the system in a circular |
| buffer giving access to the last N branches for each cpu. |
| |
| config DYNAMIC_FTRACE |
| bool "enable/disable ftrace tracepoints dynamically" |
| depends on FUNCTION_TRACER |
| depends on HAVE_DYNAMIC_FTRACE |
| depends on DEBUG_KERNEL |
| default y |
| help |
| This option will modify all the calls to ftrace dynamically |
| (will patch them out of the binary image and replaces 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. |
| |
| config FTRACE_MCOUNT_RECORD |
| def_bool y |
| depends on DYNAMIC_FTRACE |
| depends on HAVE_FTRACE_MCOUNT_RECORD |
| |
| config FTRACE_SELFTEST |
| bool |
| |
| config FTRACE_STARTUP_TEST |
| bool "Perform a startup test on ftrace" |
| depends on TRACING && DEBUG_KERNEL && !BOOT_TRACER |
| select FTRACE_SELFTEST |
| help |
| 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. |
| |
| endmenu |
