[Mesa-dev] [PATCH 4/4] st/mesa: use asynchronous flushes for glFlush

[Nicolai Hähnle]

On 09.11.2017 14:45, Nicolai Hähnle wrote:
> From: Nicolai Hähnle <nicolai.haehnle at amd.com>
> 
> Having the gallium driver thread flush in the background should be
> sufficient for glFlush semantics.
> 
> Various end-of-frame flushes (from st_context_flush and st/dri) still
> use a synchronous flush. We should eventually be able to transition
> those to asynchronous flushes as well by passing fences explicitly
> via the X protocol.

Thanks for the reviews, folks.

This last patch causes a non-deterministic regression in 
dEQP-EGL.functional.image.render_multiple_contexts.gles2_*_read_pixels

I'm pretty sure that's a test bug, and I filed an issue on Khronos' 
internal bug tracker 
(https://gitlab.khronos.org/Tracker/vk-gl-cts/issues/857). Still, I'll 
hold this particular patch for now, and only push the first three after 
some more double-checking.

Cheers,
Nicolai


> ---
>   src/mesa/state_tracker/st_cb_flush.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/src/mesa/state_tracker/st_cb_flush.c b/src/mesa/state_tracker/st_cb_flush.c
> index 14bfd5a4684..5f4e2ac3cc1 100644
> --- a/src/mesa/state_tracker/st_cb_flush.c
> +++ b/src/mesa/state_tracker/st_cb_flush.c
> @@ -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)
>   {
> 


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Aber vergiss niemals, wie sie sein sollte.