Re: [PATCH 2/9] perf, tools, stat: Support up-scaling of events

[Jiri Olsa <jolsa@redhat.com>]

On Tue, Aug 11, 2015 at 06:38:05AM -0700, Andi Kleen wrote:
> On Tue, Aug 11, 2015 at 03:25:32PM +0200, Jiri Olsa wrote:
> > On Fri, Aug 07, 2015 at 06:06:18PM -0700, Andi Kleen wrote:
> > > From: Andi Kleen <ak@linux.intel.com>
> > > 
> > > TopDown needs to multiply events by constants (for example
> > > the CPU Pipeline Width) to get the correct results.
> > > The kernel needs to export this factor.
> > > 
> > > Today *.scale is only used to scale down metrics (divide), for example
> > > to scale bytes to MB.
> > > 
> > > Repurpose negative scale to mean scaling up, that is multiplying.
> > > Implement the code for this in perf stat.
> > > 
> > > Signed-off-by: Andi Kleen <ak@linux.intel.com>
> > > ---
> > >  tools/perf/builtin-stat.c | 27 +++++++++++++++++++--------
> > >  1 file changed, 19 insertions(+), 8 deletions(-)
> > > 
> > > diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> > > index ea5298a..2590c75 100644
> > > --- a/tools/perf/builtin-stat.c
> > > +++ b/tools/perf/builtin-stat.c
> > > @@ -179,6 +179,17 @@ static inline int nsec_counter(struct perf_evsel *evsel)
> > >  	return 0;
> > >  }
> > >  
> > > +static double scale_val(struct perf_evsel *counter, u64 val)
> > > +{
> > > +	double uval = val;
> > > +
> > > +	if (counter->scale < 0)
> > > +		uval = val * (-counter->scale);
> > > +	else if (counter->scale)
> > > +		uval = val / counter->scale;
> > 
> > hum, do you change the scale logic? the current scale > 0 works like:
> > 
> > 	uval = val * counter->scale;
> 
> Yes I define negative scales to mean "multiply by" See the description of the kernel
> patch for more details.

how about existing scale attributes, like in rapl code

jirka