[Mesa-dev] [PATCH v2 1/4] anv/query: implement multiview interactions
Iago Toral
itoral at igalia.com
Thu Jan 18 06:56:12 UTC 2018
On Wed, 2018-01-17 at 13:07 -0800, Jason Ekstrand wrote:
> On Wed, Jan 17, 2018 at 1:27 AM, Iago Toral <itoral at igalia.com>
> wrote:
> > On Tue, 2018-01-16 at 08:07 -0800, Jason Ekstrand wrote:
> > > On Mon, Jan 8, 2018 at 4:57 AM, Iago Toral Quiroga <itoral at igalia
> > > .com> 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;
> > > >
> > >
> > > I think this would be better as just an if instead of an early
> > > 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);
> > > >
> > >
> > > We can't set this from the CPU, we need to emit an
> > > MI_STORE_DATA_IMM and call emit_query_availability.
> >
> > Oh ok, I'll do that then. Thanks for the feedback! Out of
> > curiosity, what is the problem with setting this on the CPU side? I
> > was thinking that since we are not emitting these queries at all
> > the GPU is not going to touch the memory for them anyway...
>
> Because they might re-use the query pool and a given slot may be
> written from the CPU or the GPU depending on how they construct the
> command buffer and they may switch back and forth for a given query.
> Also, touching it from the CPU happens immediately instead of when
> the command executes. The combination of these two things can lead
> to some very bizarre results.
Oops, of course, queries are recorded in the command buffer, that was a
silly question...
Iago
> > > > + }
> > > >
> > > > }
> > > >
> > > >
> > > >
> > > > #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);
> > > >
> > >
> > > Same comments here.
> > >
> > > > + }
> > > >
> > > > }
> > > >
> > > >
> > > >
> > > > #if GEN_GEN > 7 || GEN_IS_HASWELL
> > > >
> > > > --
> > > >
> > > > 2.11.0
> > > >
> > > >
> > > >
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