Re: [PATCH 3/3] perf, tool: Add new event group management

[Arnaldo Carvalho de Melo <acme@redhat.com>]

Em Wed, Mar 21, 2012 at 11:27:24PM +0100, Jiri Olsa escreveu:
> On Wed, Mar 21, 2012 at 12:11:19PM -0300, Arnaldo Carvalho de Melo wrote:
> > Em Wed, Mar 21, 2012 at 11:42:14AM +0100, Jiri Olsa escreveu:
> > > On Tue, Mar 20, 2012 at 07:44:41PM +0100, Peter Zijlstra wrote:
> > > > If so, we need some option like:
> > > > 
> > > >   perf record -e "{cpu-clock,cache-misses,cache-references}:1"
> > > > 
> > > > to mean, only sample on cpu-clock but use PERF_SAMPLE_READ and
> > > > PERF_FORMAT_GROUP to read all siblings on every cpu-clock sample.
> > > > 
> > > > Now the disadvantage is that {} needs quotes on bash, the advantage is
> > > > that its completely natural on how to construct groups, without weird
> > > > --group/--group parsed. Also it provides a place for group modifiers.
> > > 
> > > how about '=group' keyword followed by ':' modifier
> > >   perf record -e "cpu-clock,cache-misses,cache-references=group:1"
> > > 
> > > or '=$groupname' and use the group name in output like
> > >   perf stat -e "task-clock,context-switches=krava:1" ls
> > > 
> > >      Performance counter stats for 'ls':
> > > 
> > >           1.003695 task-clock/krava          #    0.083 CPUs utilized          
> > >                  0 context-switches/krava    #    0.000 K/sec                  
> > > 
> > 
> > Humm, interesting, perhaps putting the group name before the =event_list
> > will be more intuitive?
> > 
> > I.e.:
> > 
> >   perf stat -e "krava=task-clock,context-switches:1" ls
> 
> yep, I put it at the end because of the ':' modifier stuff.
> We have it for each event, and it'd be in conflict having
> it at the end..
> 
> maybe we could put it like:
>    perf stat -e "krava:1=task-clock,context-switches" ls
> 
> or put some other separator instead of ':' ... but ':' is the best ;)

That thought crossed my mind as well, indeed it seems more intuitive:
everything before the '=' defines the group wide attributes (name,
modifiers, whatevever else we need later) after it, the evlist, where
each evsel can have its own attributes.

- Arnaldo