Re: [RFC PATCH 2/5] perf jevents: add support for arch recommended events

[John Garry]

On 16/12/2017 18:47, Andi Kleen wrote:

Hi Andi,

> > Won't this all potentially have a big maintainence cost?
>
> No. It's all auto generated.
>
> The only cost is slightly bigger binary size.
>
> I would hope your event files are auto generated too.

No, they're not - we are just manually transcribing the event data from 
the architecture reference manual (for arch-defined events) or internal 
text document (for custom events).

Can you describe how you autogenerate the JSONs? Do you have some 
internal proprietary HW file format describing events, with files 
supplied from HW designer, which you can just translate into a JSON? 
Would the files support deferencing events to improve scalability?

> > I just don't know how this schema scales with more archs and more platforms
> > supported. It's just early days now...
>
> Only perf will get slightly bigger, but memory is not exactly expensive.
>
> In fact, the extra memory won't even be faulted in if it's not used,
> so it's only disk space.

Much appreciated,
John

> -Andi
>
> .