Re: [RFC 0/4] perf tool: Adding ratios support

[Ulrich Drepper]

On Tue, Jan 15, 2013 at 8:39 AM, Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
>   $ perf stat -f formula.conf:cpi kill
>   usage: kill [ -s signal | -p ] [ -a ] pid ...
>          kill -l [ signal ]

I do like this proposal.  The only comment I have is that perhaps the
command line syntax isn't ideal.  What you use above is tied to the
ratios be defined in the config file.  I would imagine that at least
over time (for some ratios probably right away) they become available
by default and don't require a config file.  Also, users might want to
put individualized ratio definitions in a config file which is read by
default.

How about the formulas becoming available whenever the config file is
read.  Maybe this means a few more keywords in the config file (ratio,
ratio-set, ...).  E.g.:

ratio-set branch {
          events = {instructions,branch-instructions,branch-misses}:u

          ratio branch-rate {
                  formula = branch-instructions / instructions
                  desc = branch rate
          }

          ratio branch-miss-rate {
                  formula = branch-misses / instructions
                  desc = branch misprediction rate
          }

          ratio branch-miss-ratio{
                  formula = branch-misses / branch-instructions
                  desc = branch misprediction ratio
          }
  }

You get the idea.  Maybe substitute "ratio":with "formula". Then allow
such a ratio/formula to be used just like a normal event, perhaps with
a special suffix/prefix to designate it.  This should then also mark
the events as part of a group so that the underlying counters are
scheduled in together.
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