#
|
# Architectures that offer an FUNCTION_TRACER implementation should
|
# select HAVE_FUNCTION_TRACER:
|
#
|
|
config USER_STACKTRACE_SUPPORT
|
bool
|
|
config NOP_TRACER
|
bool
|
|
config HAVE_FTRACE_NMI_ENTER
|
bool
|
help
|
See Documentation/trace/ftrace-design.rst
|
|
config HAVE_FUNCTION_TRACER
|
bool
|
help
|
See Documentation/trace/ftrace-design.rst
|
|
config HAVE_FUNCTION_GRAPH_TRACER
|
bool
|
help
|
See Documentation/trace/ftrace-design.rst
|
|
config HAVE_DYNAMIC_FTRACE
|
bool
|
help
|
See Documentation/trace/ftrace-design.rst
|
|
config HAVE_DYNAMIC_FTRACE_WITH_REGS
|
bool
|
|
config HAVE_FTRACE_MCOUNT_RECORD
|
bool
|
help
|
See Documentation/trace/ftrace-design.rst
|
|
config HAVE_SYSCALL_TRACEPOINTS
|
bool
|
help
|
See Documentation/trace/ftrace-design.rst
|
|
config HAVE_FENTRY
|
bool
|
help
|
Arch supports the gcc options -pg with -mfentry
|
|
config HAVE_NOP_MCOUNT
|
bool
|
help
|
Arch supports the gcc options -pg with -mrecord-mcount and -nop-mcount
|
|
config HAVE_C_RECORDMCOUNT
|
bool
|
help
|
C version of recordmcount available?
|
|
config TRACER_MAX_TRACE
|
bool
|
|
config TRACE_CLOCK
|
bool
|
|
config RING_BUFFER
|
bool
|
select TRACE_CLOCK
|
select IRQ_WORK
|
|
config FTRACE_NMI_ENTER
|
bool
|
depends on HAVE_FTRACE_NMI_ENTER
|
default y
|
|
config EVENT_TRACING
|
select CONTEXT_SWITCH_TRACER
|
select GLOB
|
bool
|
|
config CONTEXT_SWITCH_TRACER
|
bool
|
|
config RING_BUFFER_ALLOW_SWAP
|
bool
|
help
|
Allow the use of ring_buffer_swap_cpu.
|
Adds a very slight overhead to tracing when enabled.
|
|
config PREEMPTIRQ_TRACEPOINTS
|
bool
|
depends on TRACE_PREEMPT_TOGGLE || TRACE_IRQFLAGS
|
select TRACING
|
default y
|
help
|
Create preempt/irq toggle tracepoints if needed, so that other parts
|
of the kernel can use them to generate or add hooks to them.
|
|
# All tracer options should select GENERIC_TRACER. For those options that are
|
# enabled by all tracers (context switch and event tracer) they select TRACING.
|
# This allows those options to appear when no other tracer is selected. But the
|
# options do not appear when something else selects it. We need the two options
|
# GENERIC_TRACER and TRACING to avoid circular dependencies to accomplish the
|
# hiding of the automatic options.
|
|
config TRACING
|
bool
|
select RING_BUFFER
|
select STACKTRACE if STACKTRACE_SUPPORT
|
select TRACEPOINTS
|
select NOP_TRACER
|
select BINARY_PRINTF
|
select EVENT_TRACING
|
select TRACE_CLOCK
|
|
config GENERIC_TRACER
|
bool
|
select TRACING
|
|
#
|
# Minimum requirements an architecture has to meet for us to
|
# be able to offer generic tracing facilities:
|
#
|
config TRACING_SUPPORT
|
bool
|
depends on TRACE_IRQFLAGS_SUPPORT
|
depends on STACKTRACE_SUPPORT
|
default y
|
|
if TRACING_SUPPORT
|
|
menuconfig FTRACE
|
bool "Tracers"
|
default y if DEBUG_KERNEL
|
help
|
Enable the kernel tracing infrastructure.
|
|
if FTRACE
|
|
config FUNCTION_TRACER
|
bool "Kernel Function Tracer"
|
depends on HAVE_FUNCTION_TRACER
|
select KALLSYMS
|
select GENERIC_TRACER
|
select CONTEXT_SWITCH_TRACER
|
select GLOB
|
select TASKS_RCU if PREEMPT
|
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 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.
|
|
config FUNCTION_GRAPH_TRACER
|
bool "Kernel Function Graph Tracer"
|
depends on HAVE_FUNCTION_GRAPH_TRACER
|
depends on FUNCTION_TRACER
|
depends on !X86_32 || !CC_OPTIMIZE_FOR_SIZE
|
default y
|
help
|
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.
|
|
config TRACE_PREEMPT_TOGGLE
|
bool
|
help
|
Enables hooks which will be called when preemption is first disabled,
|
and last enabled.
|
|
config PREEMPTIRQ_EVENTS
|
bool "Enable trace events for preempt and irq disable/enable"
|
select TRACE_IRQFLAGS
|
select TRACE_PREEMPT_TOGGLE if PREEMPT
|
select GENERIC_TRACER
|
default n
|
help
|
Enable tracing of disable and enable events for preemption and irqs.
|
|
config IRQSOFF_TRACER
|
bool "Interrupts-off Latency Tracer"
|
default n
|
depends on TRACE_IRQFLAGS_SUPPORT
|
depends on !ARCH_USES_GETTIMEOFFSET
|
select TRACE_IRQFLAGS
|
select GENERIC_TRACER
|
select TRACER_MAX_TRACE
|
select RING_BUFFER_ALLOW_SWAP
|
select TRACER_SNAPSHOT
|
select TRACER_SNAPSHOT_PER_CPU_SWAP
|
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 > /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.)
|
|
config PREEMPT_TRACER
|
bool "Preemption-off Latency Tracer"
|
default n
|
depends on !ARCH_USES_GETTIMEOFFSET
|
depends on PREEMPT
|
select GENERIC_TRACER
|
select TRACER_MAX_TRACE
|
select RING_BUFFER_ALLOW_SWAP
|
select TRACER_SNAPSHOT
|
select TRACER_SNAPSHOT_PER_CPU_SWAP
|
select TRACE_PREEMPT_TOGGLE
|
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 > /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.)
|
|
config SCHED_TRACER
|
bool "Scheduling Latency Tracer"
|
select GENERIC_TRACER
|
select CONTEXT_SWITCH_TRACER
|
select TRACER_MAX_TRACE
|
select TRACER_SNAPSHOT
|
help
|
This tracer tracks the latency of the highest priority task
|
to be scheduled in, starting from the point it has woken up.
|
|
config HWLAT_TRACER
|
bool "Tracer to detect hardware latencies (like SMIs)"
|
select GENERIC_TRACER
|
help
|
This tracer, when enabled will create one or more kernel threads,
|
depending on what the cpumask file is set to, which each thread
|
spinning in a loop looking for interruptions caused by
|
something other than the kernel. For example, if a
|
System Management Interrupt (SMI) takes a noticeable amount of
|
time, this tracer will detect it. This is useful for testing
|
if a system is reliable for Real Time tasks.
|
|
Some files are created in the tracing directory when this
|
is enabled:
|
|
hwlat_detector/width - time in usecs for how long to spin for
|
hwlat_detector/window - time in usecs between the start of each
|
iteration
|
|
A kernel thread is created that will spin with interrupts disabled
|
for "width" microseconds in every "window" cycle. It will not spin
|
for "window - width" microseconds, where the system can
|
continue to operate.
|
|
The output will appear in the trace and trace_pipe files.
|
|
When the tracer is not running, it has no affect on the system,
|
but when it is running, it can cause the system to be
|
periodically non responsive. Do not run this tracer on a
|
production system.
|
|
To enable this tracer, echo in "hwlat" into the current_tracer
|
file. Every time a latency is greater than tracing_thresh, it will
|
be recorded into the ring buffer.
|
|
config ENABLE_DEFAULT_TRACERS
|
bool "Trace process context switches and events"
|
depends on !GENERIC_TRACER
|
select TRACING
|
help
|
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.
|
|
config FTRACE_SYSCALLS
|
bool "Trace syscalls"
|
depends on HAVE_SYSCALL_TRACEPOINTS
|
select GENERIC_TRACER
|
select KALLSYMS
|
help
|
Basic tracer to catch the syscall entry and exit events.
|
|
config TRACER_SNAPSHOT
|
bool "Create a snapshot trace buffer"
|
select TRACER_MAX_TRACE
|
help
|
Allow tracing users to take snapshot of the current buffer using the
|
ftrace interface, e.g.:
|
|
echo 1 > /sys/kernel/debug/tracing/snapshot
|
cat snapshot
|
|
config TRACER_SNAPSHOT_PER_CPU_SWAP
|
bool "Allow snapshot to swap per CPU"
|
depends on TRACER_SNAPSHOT
|
select RING_BUFFER_ALLOW_SWAP
|
help
|
Allow doing a snapshot of a single CPU buffer instead of a
|
full swap (all buffers). If this is set, then the following is
|
allowed:
|
|
echo 1 > /sys/kernel/debug/tracing/per_cpu/cpu2/snapshot
|
|
After which, only the tracing buffer for CPU 2 was swapped with
|
the main tracing buffer, and the other CPU buffers remain the same.
|
|
When this is enabled, this adds a little more overhead to the
|
trace recording, as it needs to add some checks to synchronize
|
recording with swaps. But this does not affect the performance
|
of the overall system. This is enabled by default when the preempt
|
or irq latency tracers are enabled, as those need to swap as well
|
and already adds the overhead (plus a lot more).
|
|
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 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.
|
|
config PROFILE_ALL_BRANCHES
|
bool "Profile all if conditionals" if !FORTIFY_SOURCE
|
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/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.
|
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 STACK_TRACER
|
bool "Trace max stack"
|
depends on HAVE_FUNCTION_TRACER
|
select FUNCTION_TRACER
|
select STACKTRACE
|
select KALLSYMS
|
help
|
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.
|
|
config BLK_DEV_IO_TRACE
|
bool "Support for tracing block IO actions"
|
depends on SYSFS
|
depends on BLOCK
|
select RELAY
|
select DEBUG_FS
|
select TRACEPOINTS
|
select GENERIC_TRACER
|
select STACKTRACE
|
help
|
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.
|
|
config KPROBE_EVENTS
|
depends on KPROBES
|
depends on HAVE_REGS_AND_STACK_ACCESS_API
|
bool "Enable kprobes-based dynamic events"
|
select TRACING
|
select PROBE_EVENTS
|
default y
|
help
|
This allows the user to add tracing events (similar to tracepoints)
|
on the fly via the ftrace interface. See
|
Documentation/trace/kprobetrace.rst 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.
|
|
config KPROBE_EVENTS_ON_NOTRACE
|
bool "Do NOT protect notrace function from kprobe events"
|
depends on KPROBE_EVENTS
|
depends on DYNAMIC_FTRACE
|
default n
|
help
|
This is only for the developers who want to debug ftrace itself
|
using kprobe events.
|
|
If kprobes can use ftrace instead of breakpoint, ftrace related
|
functions are protected from kprobe-events to prevent an infinit
|
recursion or any unexpected execution path which leads to a kernel
|
crash.
|
|
This option disables such protection and allows you to put kprobe
|
events on ftrace functions for debugging ftrace by itself.
|
Note that this might let you shoot yourself in the foot.
|
|
If unsure, say N.
|
|
config UPROBE_EVENTS
|
bool "Enable uprobes-based dynamic events"
|
depends on ARCH_SUPPORTS_UPROBES
|
depends on MMU
|
depends on PERF_EVENTS
|
select UPROBES
|
select PROBE_EVENTS
|
select TRACING
|
default y
|
help
|
This allows the user to add tracing events on top of userspace
|
dynamic events (similar to tracepoints) on the fly via the trace
|
events interface. Those events can be inserted wherever uprobes
|
can probe, and record various registers.
|
This option is required if you plan to use perf-probe subcommand
|
of perf tools on user space applications.
|
|
config BPF_EVENTS
|
depends on BPF_SYSCALL
|
depends on (KPROBE_EVENTS || UPROBE_EVENTS) && PERF_EVENTS
|
bool
|
default y
|
help
|
This allows the user to attach BPF programs to kprobe events.
|
|
config PROBE_EVENTS
|
def_bool n
|
|
config DYNAMIC_FTRACE
|
bool "enable/disable function tracing dynamically"
|
depends on FUNCTION_TRACER
|
depends on HAVE_DYNAMIC_FTRACE
|
default y
|
help
|
This option will modify all the calls to function tracing
|
dynamically (will patch them out of the binary image and
|
replace them with a No-Op instruction) on boot up. During
|
compile time, a table is made of all the locations that ftrace
|
can function trace, and this table is linked into the kernel
|
image. When this is enabled, functions can be individually
|
enabled, and the functions not enabled will not affect
|
performance of the system.
|
|
See the files in /sys/kernel/debug/tracing:
|
available_filter_functions
|
set_ftrace_filter
|
set_ftrace_notrace
|
|
This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but
|
otherwise has native performance as long as no tracing is active.
|
|
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
|
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
|
