[Mesa-dev] [PATCH] winsys/amdgpu: enlarge buffer_indices_hashlist

[Marek Olšák]

Reviewed-by: Marek Olšák <marek.olsak at amd.com>

Marek

On Tue, Mar 8, 2016 at 4:01 PM, Bas Nieuwenhuizen
<bas at basnieuwenhuizen.nl> wrote:
> Enlarge the buffer hashlist to prevent large numbers of misses
> due to adding more buffers than can be cached in the hashlist.
>
> The game I tested had CS's with up to 1500 buffers and the overhead
> of amdgpu_lookup_buffer for various sizes was:
>
> 4096 1.97% (new value)
> 2048 4.37%
> 1024 6.92%
> 512  9.47% (old value)
>
> (percentage of CPU usage in render thread as determined by perf)
>
> The time spent in amdgpu_add_buffer self is ~4.2% in all cases and
> for 4096 the time needed to clear the hashlist is still < 0.10%,
> so I am not expecting significant regressions.
>
> Signed-off-by: Bas Nieuwenhuizen <bas at basnieuwenhuizen.nl>
> ---
>  src/gallium/winsys/amdgpu/drm/amdgpu_cs.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/src/gallium/winsys/amdgpu/drm/amdgpu_cs.h b/src/gallium/winsys/amdgpu/drm/amdgpu_cs.h
> index 6ad3cdd..a2fb44a 100644
> --- a/src/gallium/winsys/amdgpu/drm/amdgpu_cs.h
> +++ b/src/gallium/winsys/amdgpu/drm/amdgpu_cs.h
> @@ -76,7 +76,7 @@ struct amdgpu_cs {
>     uint8_t                     *flags;
>     struct amdgpu_cs_buffer     *buffers;
>
> -   int                         buffer_indices_hashlist[512];
> +   int                         buffer_indices_hashlist[4096];
>
>     uint64_t                    used_vram;
>     uint64_t                    used_gart;
> --
> 2.7.2
>
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