Re: [PATCH 10/10] perf, tools, stat: Output JSON MetricExpr metric

From: Andi Kleen
Date: Thu Feb 09 2017 - 14:01:24 EST

On Thu, Feb 09, 2017 at 07:37:55PM +0100, Jiri Olsa wrote:
> > The last time I proposed separate files Ingo vetoed it.
> > He wanted everything built in.
> sure, he veto it for event files.. expressions could be built
> in same way as we have events now

That's exactly what I implemented. The expression is part
of the JSON file, which seems like the logical place.

You just want it in a separate file in the source?

> > > from which point we could point and configure events we need
> >
> > If you want full flexibility you can use your perf stat report
> > approach, or what most people do is to just run a script/spreadsheet
> > over the the -x; output. This all continues to work.
> >
> > This is just a minimum approach to provide some convenience
> > integrated with the event list to provide something similar
> > as the built in expressions in stat-shadow.
> >
> > It's not trying to build the great perf scripting language.
> yea I understand that but can't ack that based on the points
> I descibed in my other email

So what are the crucial points that prevent you?

- You want better column descriptions?

I suppose could add another field for this.

- You want multiple expressions per event
(even though they are not needed today)?

It could be implemented, but seems like unnecessary
complexity and overengineering to me at this point.
If nobody ever uses it would it be time spent well?
If someone really uses it they could add the support at that

- You want automatic group creation?

It has nasty corner cases.
It would be possible to build something that works
for simple cases.

Anything I missed?