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SubjectRe: [RFC 0/4] perf tool: Adding ratios support
On Wed, Jan 16, 2013 at 09:00:07AM -0500, Ulrich Drepper wrote:
> On Tue, Jan 15, 2013 at 8:39 AM, Jiri Olsa <jolsa@redhat.com> 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
> }
> }

I was thinking having config files (global and arch specific)
comming with perf having predefined formulas.

Plus adding the possibility to load extra config file via command
line option.

>
> 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

I like the idea of having ratios handled within event definitions
maybe even in a similar way like aliases are handled today.. like:

1) -e 'ratio/branch-rate/' # special event class
2) -e 'ratio-branch-rate' # 'ratio-' prefix
3) -e cpu/branch-rate/ # handled like aliases, ratio name would need to be unique
... ?

ideas?

Having both 2) with 3) seems good to me

> the events as part of a group so that the underlying counters are
> scheduled in together.

the 'events' definitions could be put into group by default,
meanwhile I used 'events = { ... }'

thanks,
jirka


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