[vlc-devel] [VLC 3.x 1/2] codec: dav1d: limit automatic frame thread count

[Francois Cartegnie]

Le 06/04/2021 à 14:01, Marvin Scholz a écrit :
> Without this limit, on a processor with many cores it would use
> so many frame threads that it would fail picture pool allocation.
> 
> Fix #25190
> ---
>   modules/codec/dav1d.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/modules/codec/dav1d.c b/modules/codec/dav1d.c
> index 3e44d524ed..0498492a73 100644
> --- a/modules/codec/dav1d.c
> +++ b/modules/codec/dav1d.c
> @@ -273,6 +273,7 @@ static int Decode(decoder_t *dec, block_t *block)
>   static int OpenDecoder(vlc_object_t *p_this)
>   {
>       decoder_t *dec = (decoder_t *)p_this;
> +    unsigned i_core_count = vlc_GetCPUCount();
>   
>       if (dec->fmt_in.i_codec != VLC_CODEC_AV1)
>           return VLC_EGENERIC;
> @@ -287,7 +288,7 @@ static int OpenDecoder(vlc_object_t *p_this)
>           p_sys->s.n_tile_threads = VLC_CLIP(vlc_GetCPUCount(), 1, 4);
>       p_sys->s.n_frame_threads = var_InheritInteger(p_this, "dav1d-thread-frames");
>       if (p_sys->s.n_frame_threads == 0)
> -        p_sys->s.n_frame_threads = __MAX(1, vlc_GetCPUCount());
> +        p_sys->s.n_frame_threads = (i_core_count < 16) ? i_core_count : 16;
>       p_sys->s.allocator.cookie = dec;
>       p_sys->s.allocator.alloc_picture_callback = NewPicture;
>       p_sys->s.allocator.release_picture_callback = FreePicture;
> 

I don't think the original allocation makes sense.
We should allocate a share.

You don't want to allocate more cores than frames + tiles threads in any 
cases, with some higher priority to tiles.


-- 
Francois Cartegnie
VideoLAN - VLC Developer