mirror of https://gitee.com/openkylin/linux.git
800 lines
25 KiB
Plaintext
800 lines
25 KiB
Plaintext
#
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# Architectures that offer an FUNCTION_TRACER implementation should
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# select HAVE_FUNCTION_TRACER:
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#
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config USER_STACKTRACE_SUPPORT
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bool
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config NOP_TRACER
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bool
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config HAVE_FTRACE_NMI_ENTER
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bool
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help
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See Documentation/trace/ftrace-design.rst
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config HAVE_FUNCTION_TRACER
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bool
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help
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See Documentation/trace/ftrace-design.rst
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config HAVE_FUNCTION_GRAPH_TRACER
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bool
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help
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See Documentation/trace/ftrace-design.rst
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config HAVE_DYNAMIC_FTRACE
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bool
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help
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See Documentation/trace/ftrace-design.rst
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config HAVE_DYNAMIC_FTRACE_WITH_REGS
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bool
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config HAVE_FTRACE_MCOUNT_RECORD
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bool
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help
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See Documentation/trace/ftrace-design.rst
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config HAVE_SYSCALL_TRACEPOINTS
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bool
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help
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See Documentation/trace/ftrace-design.rst
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config HAVE_FENTRY
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bool
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help
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Arch supports the gcc options -pg with -mfentry
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config HAVE_NOP_MCOUNT
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bool
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help
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Arch supports the gcc options -pg with -mrecord-mcount and -nop-mcount
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config HAVE_C_RECORDMCOUNT
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bool
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help
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C version of recordmcount available?
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config TRACER_MAX_TRACE
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bool
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config TRACE_CLOCK
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bool
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config RING_BUFFER
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bool
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select TRACE_CLOCK
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select IRQ_WORK
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config FTRACE_NMI_ENTER
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bool
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depends on HAVE_FTRACE_NMI_ENTER
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default y
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config EVENT_TRACING
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select CONTEXT_SWITCH_TRACER
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select GLOB
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bool
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config CONTEXT_SWITCH_TRACER
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bool
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config RING_BUFFER_ALLOW_SWAP
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bool
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help
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Allow the use of ring_buffer_swap_cpu.
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Adds a very slight overhead to tracing when enabled.
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config PREEMPTIRQ_TRACEPOINTS
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bool
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depends on TRACE_PREEMPT_TOGGLE || TRACE_IRQFLAGS
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select TRACING
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default y
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help
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Create preempt/irq toggle tracepoints if needed, so that other parts
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of the kernel can use them to generate or add hooks to them.
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# All tracer options should select GENERIC_TRACER. For those options that are
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# enabled by all tracers (context switch and event tracer) they select TRACING.
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# This allows those options to appear when no other tracer is selected. But the
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# options do not appear when something else selects it. We need the two options
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# GENERIC_TRACER and TRACING to avoid circular dependencies to accomplish the
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# hiding of the automatic options.
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config TRACING
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bool
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select DEBUG_FS
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select RING_BUFFER
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select STACKTRACE if STACKTRACE_SUPPORT
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select TRACEPOINTS
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select NOP_TRACER
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select BINARY_PRINTF
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select EVENT_TRACING
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select TRACE_CLOCK
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config GENERIC_TRACER
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bool
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select TRACING
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#
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# Minimum requirements an architecture has to meet for us to
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# be able to offer generic tracing facilities:
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#
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config TRACING_SUPPORT
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bool
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depends on TRACE_IRQFLAGS_SUPPORT
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depends on STACKTRACE_SUPPORT
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default y
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if TRACING_SUPPORT
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menuconfig FTRACE
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bool "Tracers"
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default y if DEBUG_KERNEL
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help
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Enable the kernel tracing infrastructure.
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if FTRACE
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config FUNCTION_TRACER
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bool "Kernel Function Tracer"
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depends on HAVE_FUNCTION_TRACER
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select KALLSYMS
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select GENERIC_TRACER
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select CONTEXT_SWITCH_TRACER
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select GLOB
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select TASKS_RCU if PREEMPT
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help
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Enable the kernel to trace every kernel function. This is done
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by using a compiler feature to insert a small, 5-byte No-Operation
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instruction at the beginning of every kernel function, which NOP
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sequence is then dynamically patched into a tracer call when
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tracing is enabled by the administrator. If it's runtime disabled
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(the bootup default), then the overhead of the instructions is very
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small and not measurable even in micro-benchmarks.
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config FUNCTION_GRAPH_TRACER
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bool "Kernel Function Graph Tracer"
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depends on HAVE_FUNCTION_GRAPH_TRACER
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depends on FUNCTION_TRACER
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depends on !X86_32 || !CC_OPTIMIZE_FOR_SIZE
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default y
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help
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Enable the kernel to trace a function at both its return
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and its entry.
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Its first purpose is to trace the duration of functions and
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draw a call graph for each thread with some information like
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the return value. This is done by setting the current return
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address on the current task structure into a stack of calls.
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config TRACE_PREEMPT_TOGGLE
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bool
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help
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Enables hooks which will be called when preemption is first disabled,
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and last enabled.
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config PREEMPTIRQ_EVENTS
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bool "Enable trace events for preempt and irq disable/enable"
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select TRACE_IRQFLAGS
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select TRACE_PREEMPT_TOGGLE if PREEMPT
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select GENERIC_TRACER
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default n
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help
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Enable tracing of disable and enable events for preemption and irqs.
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config IRQSOFF_TRACER
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bool "Interrupts-off Latency Tracer"
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default n
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depends on TRACE_IRQFLAGS_SUPPORT
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depends on !ARCH_USES_GETTIMEOFFSET
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select TRACE_IRQFLAGS
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select GENERIC_TRACER
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select TRACER_MAX_TRACE
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select RING_BUFFER_ALLOW_SWAP
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select TRACER_SNAPSHOT
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select TRACER_SNAPSHOT_PER_CPU_SWAP
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help
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This option measures the time spent in irqs-off critical
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sections, with microsecond accuracy.
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The default measurement method is a maximum search, which is
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disabled by default and can be runtime (re-)started
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via:
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echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
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(Note that kernel size and overhead increase with this option
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enabled. This option and the preempt-off timing option can be
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used together or separately.)
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config PREEMPT_TRACER
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bool "Preemption-off Latency Tracer"
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default n
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depends on !ARCH_USES_GETTIMEOFFSET
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depends on PREEMPT
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select GENERIC_TRACER
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select TRACER_MAX_TRACE
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select RING_BUFFER_ALLOW_SWAP
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select TRACER_SNAPSHOT
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select TRACER_SNAPSHOT_PER_CPU_SWAP
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select TRACE_PREEMPT_TOGGLE
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help
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This option measures the time spent in preemption-off critical
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sections, with microsecond accuracy.
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The default measurement method is a maximum search, which is
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disabled by default and can be runtime (re-)started
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via:
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echo 0 > /sys/kernel/debug/tracing/tracing_max_latency
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(Note that kernel size and overhead increase with this option
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enabled. This option and the irqs-off timing option can be
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used together or separately.)
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config SCHED_TRACER
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bool "Scheduling Latency Tracer"
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select GENERIC_TRACER
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select CONTEXT_SWITCH_TRACER
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select TRACER_MAX_TRACE
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select TRACER_SNAPSHOT
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help
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This tracer tracks the latency of the highest priority task
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to be scheduled in, starting from the point it has woken up.
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config HWLAT_TRACER
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bool "Tracer to detect hardware latencies (like SMIs)"
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select GENERIC_TRACER
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help
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This tracer, when enabled will create one or more kernel threads,
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depending on what the cpumask file is set to, which each thread
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spinning in a loop looking for interruptions caused by
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something other than the kernel. For example, if a
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System Management Interrupt (SMI) takes a noticeable amount of
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time, this tracer will detect it. This is useful for testing
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if a system is reliable for Real Time tasks.
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Some files are created in the tracing directory when this
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is enabled:
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hwlat_detector/width - time in usecs for how long to spin for
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hwlat_detector/window - time in usecs between the start of each
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iteration
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A kernel thread is created that will spin with interrupts disabled
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for "width" microseconds in every "window" cycle. It will not spin
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for "window - width" microseconds, where the system can
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continue to operate.
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The output will appear in the trace and trace_pipe files.
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When the tracer is not running, it has no affect on the system,
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but when it is running, it can cause the system to be
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periodically non responsive. Do not run this tracer on a
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production system.
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To enable this tracer, echo in "hwlat" into the current_tracer
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file. Every time a latency is greater than tracing_thresh, it will
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be recorded into the ring buffer.
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config ENABLE_DEFAULT_TRACERS
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bool "Trace process context switches and events"
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depends on !GENERIC_TRACER
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select TRACING
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help
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This tracer hooks to various trace points in the kernel,
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allowing the user to pick and choose which trace point they
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want to trace. It also includes the sched_switch tracer plugin.
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config FTRACE_SYSCALLS
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bool "Trace syscalls"
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depends on HAVE_SYSCALL_TRACEPOINTS
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select GENERIC_TRACER
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select KALLSYMS
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help
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Basic tracer to catch the syscall entry and exit events.
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config TRACER_SNAPSHOT
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bool "Create a snapshot trace buffer"
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select TRACER_MAX_TRACE
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help
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Allow tracing users to take snapshot of the current buffer using the
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ftrace interface, e.g.:
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echo 1 > /sys/kernel/debug/tracing/snapshot
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cat snapshot
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config TRACER_SNAPSHOT_PER_CPU_SWAP
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bool "Allow snapshot to swap per CPU"
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depends on TRACER_SNAPSHOT
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select RING_BUFFER_ALLOW_SWAP
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help
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Allow doing a snapshot of a single CPU buffer instead of a
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full swap (all buffers). If this is set, then the following is
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allowed:
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echo 1 > /sys/kernel/debug/tracing/per_cpu/cpu2/snapshot
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After which, only the tracing buffer for CPU 2 was swapped with
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the main tracing buffer, and the other CPU buffers remain the same.
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When this is enabled, this adds a little more overhead to the
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trace recording, as it needs to add some checks to synchronize
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recording with swaps. But this does not affect the performance
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of the overall system. This is enabled by default when the preempt
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or irq latency tracers are enabled, as those need to swap as well
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and already adds the overhead (plus a lot more).
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config TRACE_BRANCH_PROFILING
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bool
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select GENERIC_TRACER
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choice
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prompt "Branch Profiling"
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default BRANCH_PROFILE_NONE
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help
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The branch profiling is a software profiler. It will add hooks
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into the C conditionals to test which path a branch takes.
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The likely/unlikely profiler only looks at the conditions that
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are annotated with a likely or unlikely macro.
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The "all branch" profiler will profile every if-statement in the
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kernel. This profiler will also enable the likely/unlikely
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profiler.
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Either of the above profilers adds a bit of overhead to the system.
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If unsure, choose "No branch profiling".
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config BRANCH_PROFILE_NONE
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bool "No branch profiling"
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help
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No branch profiling. Branch profiling adds a bit of overhead.
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Only enable it if you want to analyse the branching behavior.
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Otherwise keep it disabled.
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config PROFILE_ANNOTATED_BRANCHES
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bool "Trace likely/unlikely profiler"
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select TRACE_BRANCH_PROFILING
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help
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This tracer profiles all likely and unlikely macros
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in the kernel. It will display the results in:
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/sys/kernel/debug/tracing/trace_stat/branch_annotated
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Note: this will add a significant overhead; only turn this
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on if you need to profile the system's use of these macros.
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config PROFILE_ALL_BRANCHES
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bool "Profile all if conditionals" if !FORTIFY_SOURCE
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select TRACE_BRANCH_PROFILING
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imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED # avoid false positives
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help
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This tracer profiles all branch conditions. Every if ()
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taken in the kernel is recorded whether it hit or miss.
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The results will be displayed in:
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/sys/kernel/debug/tracing/trace_stat/branch_all
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This option also enables the likely/unlikely profiler.
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This configuration, when enabled, will impose a great overhead
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on the system. This should only be enabled when the system
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is to be analyzed in much detail.
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endchoice
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config TRACING_BRANCHES
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bool
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help
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Selected by tracers that will trace the likely and unlikely
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conditions. This prevents the tracers themselves from being
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profiled. Profiling the tracing infrastructure can only happen
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when the likelys and unlikelys are not being traced.
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config BRANCH_TRACER
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bool "Trace likely/unlikely instances"
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depends on TRACE_BRANCH_PROFILING
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select TRACING_BRANCHES
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help
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This traces the events of likely and unlikely condition
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calls in the kernel. The difference between this and the
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"Trace likely/unlikely profiler" is that this is not a
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histogram of the callers, but actually places the calling
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events into a running trace buffer to see when and where the
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events happened, as well as their results.
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Say N if unsure.
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config STACK_TRACER
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bool "Trace max stack"
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depends on HAVE_FUNCTION_TRACER
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select FUNCTION_TRACER
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select STACKTRACE
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select KALLSYMS
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help
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This special tracer records the maximum stack footprint of the
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kernel and displays it in /sys/kernel/debug/tracing/stack_trace.
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This tracer works by hooking into every function call that the
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kernel executes, and keeping a maximum stack depth value and
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stack-trace saved. If this is configured with DYNAMIC_FTRACE
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then it will not have any overhead while the stack tracer
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is disabled.
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To enable the stack tracer on bootup, pass in 'stacktrace'
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on the kernel command line.
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The stack tracer can also be enabled or disabled via the
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sysctl kernel.stack_tracer_enabled
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Say N if unsure.
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config BLK_DEV_IO_TRACE
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bool "Support for tracing block IO actions"
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depends on SYSFS
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depends on BLOCK
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select RELAY
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select DEBUG_FS
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select TRACEPOINTS
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select GENERIC_TRACER
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select STACKTRACE
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help
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Say Y here if you want to be able to trace the block layer actions
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on a given queue. Tracing allows you to see any traffic happening
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on a block device queue. For more information (and the userspace
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support tools needed), fetch the blktrace tools from:
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git://git.kernel.dk/blktrace.git
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Tracing also is possible using the ftrace interface, e.g.:
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echo 1 > /sys/block/sda/sda1/trace/enable
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echo blk > /sys/kernel/debug/tracing/current_tracer
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cat /sys/kernel/debug/tracing/trace_pipe
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If unsure, say N.
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config KPROBE_EVENTS
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depends on KPROBES
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depends on HAVE_REGS_AND_STACK_ACCESS_API
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bool "Enable kprobes-based dynamic events"
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select TRACING
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select PROBE_EVENTS
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select DYNAMIC_EVENTS
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default y
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help
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This allows the user to add tracing events (similar to tracepoints)
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on the fly via the ftrace interface. See
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Documentation/trace/kprobetrace.rst for more details.
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Those events can be inserted wherever kprobes can probe, and record
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various register and memory values.
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This option is also required by perf-probe subcommand of perf tools.
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If you want to use perf tools, this option is strongly recommended.
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config KPROBE_EVENTS_ON_NOTRACE
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bool "Do NOT protect notrace function from kprobe events"
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depends on KPROBE_EVENTS
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depends on KPROBES_ON_FTRACE
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default n
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help
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This is only for the developers who want to debug ftrace itself
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using kprobe events.
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If kprobes can use ftrace instead of breakpoint, ftrace related
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functions are protected from kprobe-events to prevent an infinit
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recursion or any unexpected execution path which leads to a kernel
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crash.
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This option disables such protection and allows you to put kprobe
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events on ftrace functions for debugging ftrace by itself.
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Note that this might let you shoot yourself in the foot.
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If unsure, say N.
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config UPROBE_EVENTS
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bool "Enable uprobes-based dynamic events"
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depends on ARCH_SUPPORTS_UPROBES
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depends on MMU
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depends on PERF_EVENTS
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select UPROBES
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select PROBE_EVENTS
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select DYNAMIC_EVENTS
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select TRACING
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default y
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help
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This allows the user to add tracing events on top of userspace
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dynamic events (similar to tracepoints) on the fly via the trace
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events interface. Those events can be inserted wherever uprobes
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can probe, and record various registers.
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This option is required if you plan to use perf-probe subcommand
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of perf tools on user space applications.
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config BPF_EVENTS
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depends on BPF_SYSCALL
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depends on (KPROBE_EVENTS || UPROBE_EVENTS) && PERF_EVENTS
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bool
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default y
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help
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This allows the user to attach BPF programs to kprobe events.
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config DYNAMIC_EVENTS
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def_bool n
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config PROBE_EVENTS
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def_bool n
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config DYNAMIC_FTRACE
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bool "enable/disable function tracing dynamically"
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depends on FUNCTION_TRACER
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depends on HAVE_DYNAMIC_FTRACE
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default y
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help
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This option will modify all the calls to function tracing
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dynamically (will patch them out of the binary image and
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replace them with a No-Op instruction) on boot up. During
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compile time, a table is made of all the locations that ftrace
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can function trace, and this table is linked into the kernel
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image. When this is enabled, functions can be individually
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enabled, and the functions not enabled will not affect
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performance of the system.
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See the files in /sys/kernel/debug/tracing:
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available_filter_functions
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set_ftrace_filter
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set_ftrace_notrace
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This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but
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otherwise has native performance as long as no tracing is active.
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|
|
|
config DYNAMIC_FTRACE_WITH_REGS
|
|
def_bool y
|
|
depends on DYNAMIC_FTRACE
|
|
depends on HAVE_DYNAMIC_FTRACE_WITH_REGS
|
|
|
|
config FUNCTION_PROFILER
|
|
bool "Kernel function profiler"
|
|
depends on FUNCTION_TRACER
|
|
default n
|
|
help
|
|
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_stat directory; this file shows the list of functions that
|
|
have been hit and their counters.
|
|
|
|
If in doubt, say N.
|
|
|
|
config BPF_KPROBE_OVERRIDE
|
|
bool "Enable BPF programs to override a kprobed function"
|
|
depends on BPF_EVENTS
|
|
depends on FUNCTION_ERROR_INJECTION
|
|
default n
|
|
help
|
|
Allows BPF to override the execution of a probed function and
|
|
set a different return value. This is used for error injection.
|
|
|
|
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 GENERIC_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.
|
|
|
|
config EVENT_TRACE_TEST_SYSCALLS
|
|
bool "Run selftest on syscall events"
|
|
depends on FTRACE_STARTUP_TEST
|
|
help
|
|
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
|
|
|
|
config MMIOTRACE
|
|
bool "Memory mapped IO tracing"
|
|
depends on HAVE_MMIOTRACE_SUPPORT && PCI
|
|
select GENERIC_TRACER
|
|
help
|
|
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.rst.
|
|
If you are not helping to develop drivers, say N.
|
|
|
|
config TRACING_MAP
|
|
bool
|
|
depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
|
|
help
|
|
tracing_map is a special-purpose lock-free map for tracing,
|
|
separated out as a stand-alone facility in order to allow it
|
|
to be shared between multiple tracers. It isn't meant to be
|
|
generally used outside of that context, and is normally
|
|
selected by tracers that use it.
|
|
|
|
config HIST_TRIGGERS
|
|
bool "Histogram triggers"
|
|
depends on ARCH_HAVE_NMI_SAFE_CMPXCHG
|
|
select TRACING_MAP
|
|
select TRACING
|
|
select DYNAMIC_EVENTS
|
|
default n
|
|
help
|
|
Hist triggers allow one or more arbitrary trace event fields
|
|
to be aggregated into hash tables and dumped to stdout by
|
|
reading a debugfs/tracefs file. They're useful for
|
|
gathering quick and dirty (though precise) summaries of
|
|
event activity as an initial guide for further investigation
|
|
using more advanced tools.
|
|
|
|
Inter-event tracing of quantities such as latencies is also
|
|
supported using hist triggers under this option.
|
|
|
|
See Documentation/trace/histogram.rst.
|
|
If in doubt, say N.
|
|
|
|
config MMIOTRACE_TEST
|
|
tristate "Test module for mmiotrace"
|
|
depends on MMIOTRACE && m
|
|
help
|
|
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.
|
|
|
|
config TRACEPOINT_BENCHMARK
|
|
bool "Add tracepoint that benchmarks tracepoints"
|
|
help
|
|
This option creates the tracepoint "benchmark:benchmark_event".
|
|
When the tracepoint is enabled, it kicks off a kernel thread that
|
|
goes into an infinite loop (calling cond_sched() to let other tasks
|
|
run), and calls the tracepoint. Each iteration will record the time
|
|
it took to write to the tracepoint and the next iteration that
|
|
data will be passed to the tracepoint itself. That is, the tracepoint
|
|
will report the time it took to do the previous tracepoint.
|
|
The string written to the tracepoint is a static string of 128 bytes
|
|
to keep the time the same. The initial string is simply a write of
|
|
"START". The second string records the cold cache time of the first
|
|
write which is not added to the rest of the calculations.
|
|
|
|
As it is a tight loop, it benchmarks as hot cache. That's fine because
|
|
we care most about hot paths that are probably in cache already.
|
|
|
|
An example of the output:
|
|
|
|
START
|
|
first=3672 [COLD CACHED]
|
|
last=632 first=3672 max=632 min=632 avg=316 std=446 std^2=199712
|
|
last=278 first=3672 max=632 min=278 avg=303 std=316 std^2=100337
|
|
last=277 first=3672 max=632 min=277 avg=296 std=258 std^2=67064
|
|
last=273 first=3672 max=632 min=273 avg=292 std=224 std^2=50411
|
|
last=273 first=3672 max=632 min=273 avg=288 std=200 std^2=40389
|
|
last=281 first=3672 max=632 min=273 avg=287 std=183 std^2=33666
|
|
|
|
|
|
config RING_BUFFER_BENCHMARK
|
|
tristate "Ring buffer benchmark stress tester"
|
|
depends on RING_BUFFER
|
|
help
|
|
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.
|
|
|
|
config RING_BUFFER_STARTUP_TEST
|
|
bool "Ring buffer startup self test"
|
|
depends on RING_BUFFER
|
|
help
|
|
Run a simple self test on the ring buffer on boot up. Late in the
|
|
kernel boot sequence, the test will start that kicks off
|
|
a thread per cpu. Each thread will write various size events
|
|
into the ring buffer. Another thread is created to send IPIs
|
|
to each of the threads, where the IPI handler will also write
|
|
to the ring buffer, to test/stress the nesting ability.
|
|
If any anomalies are discovered, a warning will be displayed
|
|
and all ring buffers will be disabled.
|
|
|
|
The test runs for 10 seconds. This will slow your boot time
|
|
by at least 10 more seconds.
|
|
|
|
At the end of the test, statics and more checks are done.
|
|
It will output the stats of each per cpu buffer. What
|
|
was written, the sizes, what was read, what was lost, and
|
|
other similar details.
|
|
|
|
If unsure, say N
|
|
|
|
config PREEMPTIRQ_DELAY_TEST
|
|
tristate "Preempt / IRQ disable delay thread to test latency tracers"
|
|
depends on m
|
|
help
|
|
Select this option to build a test module that can help test latency
|
|
tracers by executing a preempt or irq disable section with a user
|
|
configurable delay. The module busy waits for the duration of the
|
|
critical section.
|
|
|
|
For example, the following invocation forces a one-time irq-disabled
|
|
critical section for 500us:
|
|
modprobe preemptirq_delay_test test_mode=irq delay=500000
|
|
|
|
If unsure, say N
|
|
|
|
config TRACE_EVAL_MAP_FILE
|
|
bool "Show eval mappings for trace events"
|
|
depends on TRACING
|
|
help
|
|
The "print fmt" of the trace events will show the enum/sizeof names
|
|
instead of their values. This can cause problems for user space tools
|
|
that use this string to parse the raw data as user space does not know
|
|
how to convert the string to its value.
|
|
|
|
To fix this, there's a special macro in the kernel that can be used
|
|
to convert an enum/sizeof into its value. If this macro is used, then
|
|
the print fmt strings will be converted to their values.
|
|
|
|
If something does not get converted properly, this option can be
|
|
used to show what enums/sizeof the kernel tried to convert.
|
|
|
|
This option is for debugging the conversions. A file is created
|
|
in the tracing directory called "eval_map" that will show the
|
|
names matched with their values and what trace event system they
|
|
belong too.
|
|
|
|
Normally, the mapping of the strings to values will be freed after
|
|
boot up or module load. With this option, they will not be freed, as
|
|
they are needed for the "eval_map" file. Enabling this option will
|
|
increase the memory footprint of the running kernel.
|
|
|
|
If unsure, say N
|
|
|
|
config TRACING_EVENTS_GPIO
|
|
bool "Trace gpio events"
|
|
depends on GPIOLIB
|
|
default y
|
|
help
|
|
Enable tracing events for gpio subsystem
|
|
|
|
config GCOV_PROFILE_FTRACE
|
|
bool "Enable GCOV profiling on ftrace subsystem"
|
|
depends on GCOV_KERNEL
|
|
help
|
|
Enable GCOV profiling on ftrace subsystem for checking
|
|
which functions/lines are tested.
|
|
|
|
If unsure, say N.
|
|
|
|
Note that on a kernel compiled with this config, ftrace will
|
|
run significantly slower.
|
|
|
|
endif # FTRACE
|
|
|
|
endif # TRACING_SUPPORT
|
|
|