[Mesa-dev] [PATCH] llvmpipe: fix wrong results for queries not in a scene

[Jose Fonseca]

Yes, that's definetely wrong with the newer query types.

And I agree that for most query types, the situation of nothing being drawned inside the query is too rare to be of concern.

Though I wonder if we should do better in a follow on patch for time queries -- which applications might emit indiscriminately and in huge quantity.  Maybe a shortcut to avoid the overhead of setting up a scene, switch to the rasterizer threads, wait, etc, will help getting better values. I'm not really sure it is relevant -- I suppose that a quick experiment with glretrace -pgpu might tell you whether it makes a difference or not.

Eitherway, should get this in as is for now. 

Jose

----- Original Message -----
> From: Roland Scheidegger <sroland at vmware.com>
> 
> The result isn't always 0 in this case (depends on query type),
> so instead of special casing this just use the ordinary path (should result
> in correct values thanks to initialization in query_begin/end), just
> skipping the fence wait.
> ---
>  src/gallium/drivers/llvmpipe/lp_query.c |   21 +++++++++------------
>  1 file changed, 9 insertions(+), 12 deletions(-)
> 
> diff --git a/src/gallium/drivers/llvmpipe/lp_query.c
> b/src/gallium/drivers/llvmpipe/lp_query.c
> index 386639e..1d3edff 100644
> --- a/src/gallium/drivers/llvmpipe/lp_query.c
> +++ b/src/gallium/drivers/llvmpipe/lp_query.c
> @@ -100,20 +100,17 @@ llvmpipe_get_query_result(struct pipe_context *pipe,
>     uint64_t *result = (uint64_t *)vresult;
>     int i;
>  
> -   if (!pq->fence) {
> -      /* no fence because there was no scene, so results is zero */
> -      *result = 0;
> -      return TRUE;
> -   }
> -
> -   if (!lp_fence_signalled(pq->fence)) {
> -      if (!lp_fence_issued(pq->fence))
> -         llvmpipe_flush(pipe, NULL, __FUNCTION__);
> +   if (pq->fence) {
> +      /* only have a fence if there was a scene */
> +      if (!lp_fence_signalled(pq->fence)) {
> +         if (!lp_fence_issued(pq->fence))
> +            llvmpipe_flush(pipe, NULL, __FUNCTION__);
>  
> -      if (!wait)
> -         return FALSE;
> +         if (!wait)
> +            return FALSE;
>  
> -      lp_fence_wait(pq->fence);
> +         lp_fence_wait(pq->fence);
> +      }
>     }
>  
>     /* Sum the results from each of the threads:
> --
> 1.7.9.5
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