[Mesa-dev] [PATCH v2 1/4] anv/query: implement multiview interactions

[Iago Toral]

Ignore the 1/4 in the subject, that was my mistake, this is a single
patch.

Iago

On Mon, 2018-01-08 at 13:57 +0100, Iago Toral Quiroga wrote:
> From the Vulkan spec with KHX extensions:
> 
>   "If queries are used while executing a render pass instance that
> has
>    multiview enabled, the query uses N consecutive query indices
>    in the query pool (starting at query) where N is the number of
> bits
>    set in the view mask in the subpass the query is used in.
> 
>    How the numerical results of the query are distributed among the
>    queries is implementation-dependent. For example, some
> implementations
>    may write each view's results to a distinct query, while other
>    implementations may write the total result to the first query and
> write
>    zero to the other queries. However, the sum of the results in all
> the
>    queries must accurately reflect the total result of the query
> summed
>    over all views. Applications can sum the results from all the
> queries to
>    compute the total result."
> 
> In our case we only really emit a single query (in the first query
> index)
> that stores the aggregated result for all views, but we still need to
> manage
> availability for all the other query indices involved, even if we
> don't
> actually use them.
> 
> This is relevant when clients call vkGetQueryPoolResults and pass all
> N
> queries to retrieve the results. In that scenario, without this
> patch,
> we will never see queries other than the first being available since
> we
> never emit them.
> 
> Fixes test failures in some work-in-progress CTS multiview+query
> tests.
> ---
>  src/intel/vulkan/genX_query.c | 36
> ++++++++++++++++++++++++++++++++++++
>  1 file changed, 36 insertions(+)
> 
> diff --git a/src/intel/vulkan/genX_query.c
> b/src/intel/vulkan/genX_query.c
> index 7683d0d1e3..231c605b6b 100644
> --- a/src/intel/vulkan/genX_query.c
> +++ b/src/intel/vulkan/genX_query.c
> @@ -462,6 +462,24 @@ void genX(CmdEndQuery)(
>     default:
>        unreachable("");
>     }
> +
> +   /* When multiview is active the spec requires that N consecutive
> query
> +    * indices are used, where N is the number of active views in the
> subpass.
> +    * The spec allows that we only write the results to one of the
> queries
> +    * but we still need to manage result availability for all the
> query indices.
> +    * Since we only emit a single query for all active views in the
> +    * first index, mark the other query indices as being already
> available
> +    * with result 0.
> +    */
> +   if (!cmd_buffer->state.subpass || !cmd_buffer->state.subpass-
> >view_mask)
> +      return;
> +
> +   uint32_t num_queries = _mesa_bitcount(cmd_buffer->state.subpass-
> >view_mask);
> +   for (uint32_t i = 1; i < num_queries; i++) {
> +      uint64_t *slot = pool->bo.map + (query + i) * pool->stride;
> +      slot[0] = 1;
> +      memset(&slot[1], 0, sizeof(uint64_t) * pool->stride);
> +   }
>  }
>  
>  #define TIMESTAMP 0x2358
> @@ -504,6 +522,24 @@ void genX(CmdWriteTimestamp)(
>     }
>  
>     emit_query_availability(cmd_buffer, &pool->bo, offset);
> +
> +   /* When multiview is active the spec requires that N consecutive
> query
> +    * indices are used, where N is the number of active views in the
> subpass.
> +    * The spec allows that we only write the results to one of the
> queries
> +    * but we still need to manage result availability for all the
> query indices.
> +    * Since we only emit a single query for all active views in the
> +    * first index, mark the other query indices as being already
> available
> +    * with result 0.
> +    */
> +   if (!cmd_buffer->state.subpass || !cmd_buffer->state.subpass-
> >view_mask)
> +      return;
> +
> +   uint32_t num_queries = _mesa_bitcount(cmd_buffer->state.subpass-
> >view_mask);
> +   for (uint32_t i = 1; i < num_queries; i++) {
> +      uint64_t *slot = pool->bo.map + (query + i) * pool->stride;
> +      slot[0] = 1;
> +      memset(&slot[1], 0, sizeof(uint64_t) * pool->stride);
> +   }
>  }
>  
>  #if GEN_GEN > 7 || GEN_IS_HASWELL