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authorTom Zanussi <zanussi@kernel.org>2020-04-03 14:31:21 -0500
committerSteven Rostedt (VMware) <rostedt@goodmis.org>2020-06-01 08:22:30 -0400
commit2d19bd79ae6509858582a9cade739c2e9a4fdca8 (patch)
tree7612f1c6d4821e70b8b69d91a0608ae68c4d3413 /kernel/trace/Kconfig
parent16b585fe71924b3aebaef5548a291021efaf7c7f (diff)
tracing: Add hist_debug trace event files for histogram debugging
Add a new "hist_debug" file for each trace event, which when read will dump out a bunch of internal details about the hist triggers defined on that event. This is normally off but can be enabled by saying 'y' to the new CONFIG_HIST_TRIGGERS_DEBUG config option. This is in support of the new Documentation file describing histogram internals, Documentation/trace/histogram-design.rst, which was requested by developers trying to understand the internals when extending or making use of the hist triggers for higher-level tools. The histogram-design.rst documentation refers to the hist_debug files and demonstrates their use with output in the test examples. Link: http://lkml.kernel.org/r/77914c22b0ba493d9783c53bbfbc6087d6a7e1b1.1585941485.git.zanussi@kernel.org Signed-off-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace/Kconfig')
-rw-r--r--kernel/trace/Kconfig23
1 files changed, 23 insertions, 0 deletions
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 743647005f64..2aec9376825f 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -847,6 +847,29 @@ config KPROBE_EVENT_GEN_TEST
If unsure, say N.
+config HIST_TRIGGERS_DEBUG
+ bool "Hist trigger debug support"
+ depends on HIST_TRIGGERS
+ help
+ Add "hist_debug" file for each event, which when read will
+ dump out a bunch of internal details about the hist triggers
+ defined on that event.
+
+ The hist_debug file serves a couple of purposes:
+
+ - Helps developers verify that nothing is broken.
+
+ - Provides educational information to support the details
+ of the hist trigger internals as described by
+ Documentation/trace/histogram-design.rst.
+
+ The hist_debug output only covers the data structures
+ related to the histogram definitions themselves and doesn't
+ display the internals of map buckets or variable values of
+ running histograms.
+
+ If unsure, say N.
+
endif # FTRACE
endif # TRACING_SUPPORT