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    SubjectRe: [PATCH v11 10/24] perf config: Document variables for 'call-graph' section in man page
    On Tue, Nov 17, 2015 at 10:53:30PM +0900, Taeung Song wrote:
    > Explain 'call-graph' section and its variables.
    >
    > 'record-mode', 'dump-size', 'print-type', 'order',
    > 'sort-key', 'threshold' and 'print-limit'.
    >
    > Cc: Namhyung Kim <namhyung@kernel.org>
    > Cc: Jiri Olsa <jolsa@redhat.com>
    > Signed-off-by: Taeung Song <treeze.taeung@gmail.com>
    > ---
    > 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.
    >
    > +call-graph.*::
    > + 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'.

    Also 'lbr' can be used, but it only work for recent intel cpus.


    > + 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.

    I think the last sentence can be omitted.


    > +
    > + 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.

    This contradicts the above, it'll use the default size if omitted.


    > +
    > + 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

    ^
    it needs one more whitespace


    > +
    > + 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 (%).

    s/threashold/threshold/

    Also it'd be better to mention that the overhead is calculated by
    value depends on call-graph.print-type.


    > +
    > + 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.

    This is a maximum number of lines of callchain printed for a single
    histogram entry.

    Thanks,
    Namhyung


    > +
    > SEE ALSO
    > --------
    > linkperf:perf[1]
    > --
    > 1.9.1
    >


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