[Mesa-dev] [PATCH 3/5] st/mesa: use asynchronous flushes

[Marek Olšák]

On Sun, Oct 22, 2017 at 9:18 PM, Nicolai Hähnle <nhaehnle at gmail.com> wrote:
> From: Nicolai Hähnle <nicolai.haehnle at amd.com>
>
> ---
>  src/mesa/state_tracker/st_cb_flush.c   |  4 ++--
>  src/mesa/state_tracker/st_cb_syncobj.c | 26 ++++++++++++++++++++++++--
>  2 files changed, 26 insertions(+), 4 deletions(-)
>
> diff --git a/src/mesa/state_tracker/st_cb_flush.c b/src/mesa/state_tracker/st_cb_flush.c
> index c8452d0e6f7..5f4e2ac3cc1 100644
> --- a/src/mesa/state_tracker/st_cb_flush.c
> +++ b/src/mesa/state_tracker/st_cb_flush.c
> @@ -56,21 +56,21 @@ void st_flush(struct st_context *st,
>  }
>
>
>  /**
>   * Flush, and wait for completion.
>   */
>  void st_finish( struct st_context *st )
>  {
>     struct pipe_fence_handle *fence = NULL;
>
> -   st_flush(st, &fence, 0);
> +   st_flush(st, &fence, PIPE_FLUSH_ASYNC | PIPE_FLUSH_HINT_FINISH);
>
>     if(fence) {
>        st->pipe->screen->fence_finish(st->pipe->screen, NULL, fence,
>                                       PIPE_TIMEOUT_INFINITE);
>        st->pipe->screen->fence_reference(st->pipe->screen, &fence, NULL);
>     }
>
>     st_manager_flush_swapbuffers();
>  }
>
> @@ -81,21 +81,21 @@ void st_finish( struct st_context *st )
>   */
>  static void st_glFlush(struct gl_context *ctx)
>  {
>     struct st_context *st = st_context(ctx);
>
>     /* Don't call st_finish() here.  It is not the state tracker's
>      * responsibilty to inject sleeps in the hope of avoiding buffer
>      * synchronization issues.  Calling finish() here will just hide
>      * problems that need to be fixed elsewhere.
>      */
> -   st_flush(st, NULL, 0);
> +   st_flush(st, NULL, PIPE_FLUSH_ASYNC);
>
>     st_manager_flush_frontbuffer(st);
>  }
>
>
>  /**
>   * Called via ctx->Driver.Finish()
>   */
>  static void st_glFinish(struct gl_context *ctx)
>  {
> diff --git a/src/mesa/state_tracker/st_cb_syncobj.c b/src/mesa/state_tracker/st_cb_syncobj.c
> index 637fbe3b73a..44323b4750a 100644
> --- a/src/mesa/state_tracker/st_cb_syncobj.c
> +++ b/src/mesa/state_tracker/st_cb_syncobj.c
> @@ -123,22 +123,44 @@ static void st_client_wait_sync(struct gl_context *ctx,
>
>  static void st_check_sync(struct gl_context *ctx, struct gl_sync_object *obj)
>  {
>     st_client_wait_sync(ctx, obj, 0, 0);
>  }
>
>  static void st_server_wait_sync(struct gl_context *ctx,
>                                  struct gl_sync_object *obj,
>                                  GLbitfield flags, GLuint64 timeout)
>  {
> -   /* NO-OP.
> -    * Neither Gallium nor DRM interfaces support blocking on the GPU. */
> +   struct pipe_context *pipe = st_context(ctx)->pipe;
> +   struct pipe_screen *screen = pipe->screen;
> +   struct st_sync_object *so = (struct st_sync_object*)obj;
> +   struct pipe_fence_handle *fence = NULL;
> +
> +   /* Nothing needs to be done here if the driver does not support async
> +    * flushes. */
> +   if (!pipe->fence_server_sync)
> +      return;
> +
> +   /* If the fence doesn't exist, assume it's signalled. */
> +   mtx_lock(&so->mutex);
> +   if (!so->fence) {
> +      mtx_unlock(&so->mutex);
> +      so->b.StatusFlag = GL_TRUE;
> +      return;
> +   }
> +
> +   /* We need a local copy of the fence pointer. */
> +   screen->fence_reference(screen, &fence, so->fence);
> +   mtx_unlock(&so->mutex);
> +
> +   pipe->fence_server_sync(pipe, fence);
> +   screen->fence_reference(screen, &fence, NULL);
>  }

What's the reason for implementing st_server_wait_sync?

Marek