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

From: Taeung Song
Date: Sun Nov 29 2015 - 20:42:13 EST


Hi, Namhyung


> On Nov 18, 2015, at 11:51 AM, Namhyung Kim <namhyung@xxxxxxxxxx> wrote:
>
> 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@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.
>>
>> +call-graph.*::
>> + When sub-commands 'top' and 'report' work with -g/â-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
>

I checked this patch file and whitespace and tab characters on it.
But I think the lacking whitespace because of mail client.
After 'make installâ I checked it but there is no lack of whitespace.
Are there different problems that I missed ?


Thanks,
Taeung

>
>> +
>> + 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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