Re: [PATCH 08/15] perf stat: Document --detailed option

From: Ingo Molnar
Date: Tue Mar 08 2016 - 04:10:31 EST

* Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> wrote:

> From: Borislav Petkov <bp@xxxxxxx>
> I'm surprised this remained undocumented since at least 2011. And it is
> actually a very useful switch, as Steve and I came to realize recently.
> Add the text from
> 2cba3ffb9a9d ("perf stat: Add -d -d and -d -d -d options to show more CPU events")
> which added the incrementing aspect to -d.

Ah yes, my fault ...

> Signed-off-by: Borislav Petkov <bp@xxxxxxx>
> Tested-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> Cc: Davidlohr Bueso <dbueso@xxxxxxxx>
> Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
> Cc: Mel Gorman <mgorman@xxxxxxxx>
> Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
> Fixes: 2cba3ffb9a9d ("perf stat: Add -d -d and -d -d -d options to show more CPU events")
> Link:
> Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> ---
> tools/perf/Documentation/perf-stat.txt | 8 ++++++++
> 1 file changed, 8 insertions(+)
> diff --git a/tools/perf/Documentation/perf-stat.txt b/tools/perf/Documentation/perf-stat.txt
> index 52ef7a9d50aa..14d9e8ffaff7 100644
> --- a/tools/perf/Documentation/perf-stat.txt
> +++ b/tools/perf/Documentation/perf-stat.txt
> @@ -69,6 +69,14 @@ report::
> --scale::
> scale/normalize counter values
> +-d::
> +--detailed::
> + print more detailed statistics, can be specified up to 3 times
> +
> + -d: detailed events, L1 and LLC data cache
> + -d -d: more detailed events, dTLB and iTLB events
> + -d -d -d: very detailed events, adding prefetch events

Btw., something I noticed: it would be really nice if 'perf stat -h -d' printed
the most detailed documentation available for the option. Right now it prints:

triton:~/tip/tools/perf> perf stat -h -d

Usage: perf stat [<options>] [<command>]

-d, --detailed detailed run - start a lot of events

The only way to get to the most detailed documentation is the not very obvious
path of:

perf help stat

and then searching for '-d'.

Ideally there should only be a single place to document options - but I guess
unifying the in-code option descriptions and more verbose description in the man
pages is very non-trivial ...