config RING_BUFFER
bool
select TRACE_CLOCK
+ select IRQ_WORK
config FTRACE_NMI_ENTER
bool
select BINARY_PRINTF
select EVENT_TRACING
select TRACE_CLOCK
- select IRQ_WORK
config GENERIC_TRACER
bool
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.
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 preemption-off critical
sections, with microsecond accuracy.
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.
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
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
+
endif # FTRACE
endif # TRACING_SUPPORT