[PATCH v11 10/24] perf config: Document variables for 'call-graph' section in man page

From: Taeung Song
Date: Tue Nov 17 2015 - 13:31:38 EST

Explain 'call-graph' section and its variables.

'record-mode', 'dump-size', 'print-type', 'order',
'sort-key', 'threshold' and 'print-limit'.

Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Signed-off-by: Taeung Song <treeze.taeung@xxxxxxxxx>
tools/perf/Documentation/perf-config.txt | 65 ++++++++++++++++++++++++++++++++
1 file changed, 65 insertions(+)

diff --git a/tools/perf/Documentation/perf-config.txt b/tools/perf/Documentation/perf-config.txt
index 7d386d4..dc659d6 100644
--- a/tools/perf/Documentation/perf-config.txt
+++ b/tools/perf/Documentation/perf-config.txt
@@ -285,6 +285,71 @@ ui.*::
There're columns as header 'Overhead', 'Children', 'Shared Object', 'Symbol', 'self'.
If this option is false, they are hiden. This option is only applied to TUI.

+ When sub-commands 'top' and 'report' work with -g/—-children
+ there're options in control of call-graph.
+ call-graph.record-mode::
+ The record-mode can be 'fp' (frame pointer) and 'dwarf'.
+ The value of 'dwarf' is effective only if perf detect needed library
+ (libunwind or a recent version of libdw). Also it doesn't *require*
+ the dump-size option since it can use the default value of 8192 if
+ missing.
+ call-graph.dump-size::
+ The size of stack to dump in order to do post-unwinding. Default is 8192 (byte).
+ When using dwarf into record-mode this option should have a value.
+ call-graph.print-type::
+ The print-types can be graph (graph absolute), fractal (graph relative), flat.
+ This option controls a way to show overhead for each callchain entry.
+ Suppose a following example.
+ Overhead Symbols
+ ........ .......
+ 40.00% foo
+ |
+ --- foo
+ |
+ |--50.00%-- bar
+ | main
+ |
+ --50.00%-- baz
+ main
+ This output is a 'fractal' format. The 'foo' came from 'bar' and 'baz' exactly
+ half and half so 'fractal' shows 50.00% for each
+ (meaning that it assumes 100% total overhead of 'foo').
+ The 'graph' uses absolute overhead value of 'foo' as total so each of
+ 'bar' and 'baz' callchain will have 20.00% of overhead.
+ call-graph.order::
+ This option controls print order of callchains. The default is
+ 'callee' which means callee is printed at top and then followed by its
+ caller and so on. The 'caller' prints it in reverse order.
+ If this option is not set and report.children or top.children is
+ set to true (or the equivalent command line option is given),
+ the default value of this option is changed to 'caller' for the
+ execution of 'perf report' or 'perf top'. Other commands will
+ still default to 'callee'.
+ call-graph.sort-key::
+ The callchains are merged if they contain same information.
+ The sort-key option determines a way to compare the callchains.
+ A value of 'sort-key' can be 'function' or 'address'.
+ The default is 'function'.
+ call-graph.threshold::
+ When there're many callchains it'd print tons of lines. So perf omits
+ small callchains under a certain overhead (threshold) and this option
+ control the threashold. Default is 0.5 (%).
+ call-graph.print-limit::
+ This is another way to control the number of callchains printed for a
+ single entry. Default is 0 which means no limitation.

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