Re: [PATCH V3 20/37] perf script: Add 'synth' event type for synthesized events

[Arnaldo Carvalho de Melo]

Em Wed, Jun 21, 2017 at 01:17:19PM +0300, Adrian Hunter escreveu:
> +++ b/tools/perf/util/event.h
> @@ -252,6 +252,9 @@ enum auxtrace_error_type {
>        PERF_AUXTRACE_ERROR_MAX
> };

> +/* Attribute type for custom synthesized events */
> +#define PERF_TYPE_SYNTH		3000000000

Why don't you make it PERF_TYPE_MAX and bump PERF_TYPE_MAX by one? I.e.
this way we have what can be in attr.type in a nice enumeration, can
validate it more easily (attr.type < PERF_TYPE_MAX) and will not need to 
do those conversions to/from OUTPUT_TYPE_/PERF_TYPE_).

Peter: now its not the PERF_RECORD_ namespace that userspaces want a
chunk of, its PERF_TYPE_, which so far has been pretty stable, grabing
_one_ for event synthesizing things like Intel PT (and ARM's coresight,
I think) directly at include/uapi/linux/perf_event.h's perf_type_id enum
looks cleaner, no?

- Arnaldo