[Mesa-dev] [PATCH resend] mesa: Add core support for the GL_AMD_performance_monitor extension.

[Christoph Bumiller]

On 12.04.2013 21:14, Kenneth Graunke wrote:
> This provides an interface for applications (and OpenGL-based tools) to
> access GPU performance counters.  Since the exact performance counters
> available vary between vendors and hardware generations, the extension
> provides an API the application can use to get the names, types, and
> minimum/maximum values of all available counters.  Counters are also
> organized into groups.
>
> Applications create "performance monitor" objects, select the counters
> they want to track, and Begin/End monitoring, much like OpenGL's query
> API.  Multiple monitors can be in flight simultaneously.
>
> We chose not to implement the similar GL_INTEL_performance_queries
> extension because Intel has not bothered to publish a specification in
> the OpenGL registry.
>
> Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
> ---
>  src/mapi/glapi/gen/AMD_performance_monitor.xml |  87 ++++
>  src/mapi/glapi/gen/Makefile.am                 |   1 +
>  src/mapi/glapi/gen/gl_API.xml                  |   2 +
>  src/mapi/glapi/gen/gl_genexec.py               |   1 +
>  src/mesa/SConscript                            |   1 +
>  src/mesa/main/context.c                        |   2 +
>  src/mesa/main/dd.h                             |  22 +
>  src/mesa/main/extensions.c                     |   1 +
>  src/mesa/main/mtypes.h                         |  84 ++++
>  src/mesa/main/performance_monitor.c            | 563 +++++++++++++++++++++++++
>  src/mesa/main/performance_monitor.h            |  85 ++++
>  src/mesa/sources.mak                           |   1 +
>  12 files changed, 850 insertions(+)
>  create mode 100644 src/mapi/glapi/gen/AMD_performance_monitor.xml
>  create mode 100644 src/mesa/main/performance_monitor.c
>  create mode 100644 src/mesa/main/performance_monitor.h
>  
>  /**
> + * A "performance monitor" as described in AMD_performance_monitor.
> + */
> +struct gl_perf_monitor_object
> +{
> +   GLboolean Active;
> +
> +   /* Actually BITSET_WORD but we can't #include that here. */
> +   GLuint *ActiveCounters;
> +};
> +

Started to implement this for mesa/st, got a question about ActiveCounters:

Does this bitset refer to the counter IDs or the Counters array index ?
Do the IDs have to be consecutive ? Do they have to correspond to the
array index ?

> +
> +void GLAPIENTRY
> +_mesa_SelectPerfMonitorCountersAMD(GLuint monitor, GLboolean enable,
> +                                   GLuint group, GLint numCounters,
> +                                   GLuint *counterList)
> +{
...
> +   if (enable) {
> +      /* Enable the counters */
> +      for (i = 0; i < numCounters; i++) {
> +         BITSET_SET(m->ActiveCounters, counterList[i]);
> +      }
> +   } else {
> +      /* Disable the counters */
> +      for (i = 0; i < numCounters; i++) {
> +         BITSET_CLEAR(m->ActiveCounters, counterList[i]);
> +      }
> +   }
> +}

counterList is an ID, so this implies ActiveCounters refers to IDs.

You also do:

m->ActiveCounters = calloc(ctx->PerfMonitor.NumCounters, sizeof(BITSET_WORD));

So, this implies it refers to the Counters array of size NumCounters
(unless the overallocation by 8 * sizeof(BITSET_WORD) bits has some
purpose that escapes me).

Hence, we cannot freely select IDs, can we ?
I had different graciously spaced ranges of gallium query IDs reserved
of different counter domains (since I haven't added all possible
counters, I don't even know all of them, needs REing), so I guess I have
to remap them in the state tracker ...

Anyway, I think this should be mentioned in a comment [that is easy to
find].

Thanks,
Christoph