[PATCH 0/7] A few drm_syncobj optimisations

[Maíra Canal]

Hi Tvrtko,

Thanks for this patchset! I applied this patchset to the RPi downstream
kernel 6.13.7 [1] and saw an FPS improvement of approximately 5.85%
with "vkgears -present-mailbox" on the RPi 5.

I did five 100 seconds runs on each kernel and here are my results:

### 6.13.7

|   Run    |   Min FPS   |   Max FPS   |   Avg FPS   |
|----------|-------------|-------------|-------------|
| Run #1   | 6646.52     | 6874.77     | 6739.313    |
| Run #2   | 5387.04     | 6723.274    | 6046.773    |
| Run #3   | 6230.49     | 6823.47     | 6423.923    |
| Run #4   | 5269.678    | 5870.59     | 5501.858    |
| Run #5   | 5504.54     | 6285.91     | 5859.724    |

* Overall Avg FPS: 6114.318 FPS


### 6.13.7 + DRM Syncobj optimisations

|   Run    |   Min FPS   |   Max FPS   |   Avg FPS   |
|----------|-------------|-------------|-------------|
| Run #1   | 6089.05     | 7296.27     | 6859.724    |
| Run #2   | 6022.48     | 7264        | 6818.518    |
| Run #3   | 5987.68     | 6188.77     | 6041.365    |
| Run #4   | 5699.27     | 6448.99     | 6190.374    |
| Run #5   | 6199.27     | 6791.15     | 6450.900    |

* Overall Avg FPS: 6472.176 FPS

[1] https://github.com/raspberrypi/linux/tree/rpi-6.13.y

Best Regards,
- Maíra

On 18/03/25 12:54, Tvrtko Ursulin wrote:
> A small set of drm_syncobj optimisations which should make things a tiny bit
> more efficient on the CPU side of things.
> 
> Improvement seems to be around 1.5%* more FPS if observed with "vkgears
> -present-mailbox" on a Steam Deck Plasma desktop, but I am reluctant to make a
> definitive claim on the numbers since there is some run to run variance. But, as
> suggested by Michel Dänzer, I did do a five ~100 second runs on the each kernel
> to be able to show the ministat analysis.
> 
> x before
> + after
> +------------------------------------------------------------+
> |                          x         +                       |
> |                   x      x         +                       |
> |                   x      xx      ++++                      |
> |                 x x      xx x    ++++                      |
> |                 x xx   x xx x+   ++++                      |
> |                xxxxx   xxxxxx+   ++++ + +                  |
> |                xxxxxxx xxxxxx+x  ++++ +++                  |
> |              x xxxxxxxxxxx*xx+* x++++++++   ++             |
> |        x x   xxxxxxxxxxxx**x*+*+*++++++++ ++++ +           |
> |       xx x   xxxxxxxxxx*x****+***+**+++++ ++++++           |
> |x     xxx x   xxxxx*x****x***********+*++**+++++++   +  +  +|
> |               |_______A______|                             |
> |                             |______A_______|               |
> +------------------------------------------------------------+
>      N           Min           Max        Median           Avg        Stddev
> x 135      21697.58     22809.467     22321.396     22307.707     198.75011
> + 118     22200.746      23277.09       22661.4     22671.442     192.10609
> Difference at 95.0% confidence
>      363.735 +/- 48.3345
>      1.63054% +/- 0.216672%
>      (Student's t, pooled s = 195.681)
> 
> Tvrtko Ursulin (7):
>    drm/syncobj: Remove unhelpful helper
>    drm/syncobj: Do not allocate an array to store zeros when waiting
>    drm/syncobj: Avoid one temporary allocation in drm_syncobj_array_find
>    drm/syncobj: Use put_user in drm_syncobj_query_ioctl
>    drm/syncobj: Avoid temporary allocation in
>      drm_syncobj_timeline_signal_ioctl
>    drm/syncobj: Add a fast path to drm_syncobj_array_wait_timeout
>    drm/syncobj: Add a fast path to drm_syncobj_array_find
> 
>   drivers/gpu/drm/drm_syncobj.c | 281 ++++++++++++++++++----------------
>   1 file changed, 147 insertions(+), 134 deletions(-)
>