[PATCH v2 0/6] drm/v3d: Improve Performance Counters handling

[Jani Nikula]

On Mon, 20 May 2024, Maíra Canal <mcanal at igalia.com> wrote:
> On 5/12/24 19:23, Maíra Canal wrote:>
>> Maíra Canal (6):
>>    drm/v3d: Add Performance Counters descriptions for V3D 4.2 and 7.1
>>    drm/v3d: Different V3D versions can have different number of perfcnt
>>    drm/v3d: Create a new V3D parameter for the maximum number of perfcnt
>>    drm/v3d: Create new IOCTL to expose performance counters information
>>    drm/v3d: Use V3D_MAX_COUNTERS instead of V3D_PERFCNT_NUM
>>    drm/v3d: Deprecate the use of the Performance Counters enum >
>>   drivers/gpu/drm/v3d/v3d_drv.c                 |  11 +
>>   drivers/gpu/drm/v3d/v3d_drv.h                 |  14 +-
>>   drivers/gpu/drm/v3d/v3d_perfmon.c             |  36 ++-
>>   .../gpu/drm/v3d/v3d_performance_counters.h    | 208 ++++++++++++++++++
>>   drivers/gpu/drm/v3d/v3d_sched.c               |   2 +-
>>   include/uapi/drm/v3d_drm.h                    |  48 ++++
>>   6 files changed, 316 insertions(+), 3 deletions(-)
>>   create mode 100644 drivers/gpu/drm/v3d/v3d_performance_counters.h
>> 
>
> Applied to drm-misc/drm-misc-next!

What compiler do you use? I'm hitting the same as kernel test robot [1]
with arm-linux-gnueabihf-gcc 12.2.0.

In general, I don't think it's a great idea to put arrays in headers,
and then include it everywhere via v3d_drv.h. You're not just relying on
the compiler to optimize it away in compilation units where its not
referenced (likely to happen), but also for the linker to deduplicate
rodata (possible, but I'm not sure that it will happen).

I think you need to move the arrays to a .c file, and then either a) add
interfaces to access the arrays, or b) declare the arrays and make them
global. For the latter you also need to figure out how to expose the
size.

BR,
Jani.


[1] https://lore.kernel.org/r/202405211137.hueFkLKG-lkp@intel.com


-- 
Jani Nikula, Intel