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-rw-r--r--kernel/trace/Kconfig73
1 files changed, 63 insertions, 10 deletions
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 192473b22799..5e9efd4b83a4 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -176,6 +176,8 @@ config IRQSOFF_TRACER
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.
@@ -198,6 +200,8 @@ config PREEMPT_TRACER
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.
@@ -217,6 +221,7 @@ config SCHED_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.
@@ -248,6 +253,27 @@ config TRACER_SNAPSHOT
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
@@ -414,24 +440,28 @@ config PROBE_EVENTS
def_bool n
config DYNAMIC_FTRACE
- bool "enable/disable ftrace tracepoints dynamically"
+ 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 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 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.
- 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 DYNAMIC_FTRACE_WITH_REGS
def_bool y
depends on DYNAMIC_FTRACE
@@ -520,6 +550,29 @@ config RING_BUFFER_BENCHMARK
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