[Mesa-dev] [PATCH] nouveau: avoid emitting new fences unnecessarily

[Samuel Pitoiset]

Does this fix those texelFetch piglit tests ? Or is it the second patch ?

Anyway, this patch is :

Reviewed-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>

On 10/10/2015 08:12 AM, Ilia Mirkin wrote:
> Right now we emit on every kick, but this is only necessary if something
> will ever be able to observe that the fence completed. If there are no
> refs, leave the fence alone and emit it another day.
>
> This also happens to work around an issue for the kick handler -- a kick
> can be a result of e.g. nouveau_bo_wait or explicit kick, or it can be
> due to lack of space in the pushbuf. We want the emit to happen in the
> current batch, so we want there to always be enough space. However an
> explicit kick could take the reserved space for the implicitly-triggered
> kick's fence emission if it happened right after. With the new mechanism,
> hopefully there's no way to cause two fences to be emitted into the same
> reserved space.
>
> Signed-off-by: Ilia Mirkin <imirkin at alum.mit.edu>
> Cc: mesa-stable at lists.freedesktop.org
> Fixes: 47d11990b (nouveau: make sure there's always room to emit a fence)
> ---
>   src/gallium/drivers/nouveau/nouveau_fence.c | 12 +++++++++---
>   1 file changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/src/gallium/drivers/nouveau/nouveau_fence.c b/src/gallium/drivers/nouveau/nouveau_fence.c
> index ee4e08d..18b1592 100644
> --- a/src/gallium/drivers/nouveau/nouveau_fence.c
> +++ b/src/gallium/drivers/nouveau/nouveau_fence.c
> @@ -190,8 +190,10 @@ nouveau_fence_wait(struct nouveau_fence *fence)
>      /* wtf, someone is waiting on a fence in flush_notify handler? */
>      assert(fence->state != NOUVEAU_FENCE_STATE_EMITTING);
>   
> -   if (fence->state < NOUVEAU_FENCE_STATE_EMITTED)
> +   if (fence->state < NOUVEAU_FENCE_STATE_EMITTED) {
> +      PUSH_SPACE(screen->pushbuf, 8);
>         nouveau_fence_emit(fence);
> +   }
>   
>      if (fence->state < NOUVEAU_FENCE_STATE_FLUSHED)
>         if (nouveau_pushbuf_kick(screen->pushbuf, screen->pushbuf->channel))
> @@ -224,8 +226,12 @@ nouveau_fence_wait(struct nouveau_fence *fence)
>   void
>   nouveau_fence_next(struct nouveau_screen *screen)
>   {
> -   if (screen->fence.current->state < NOUVEAU_FENCE_STATE_EMITTING)
> -      nouveau_fence_emit(screen->fence.current);
> +   if (screen->fence.current->state < NOUVEAU_FENCE_STATE_EMITTING) {
> +      if (screen->fence.current->ref > 1)
> +         nouveau_fence_emit(screen->fence.current);
> +      else
> +         return;
> +   }
>   
>      nouveau_fence_ref(NULL, &screen->fence.current);
>