[Mesa-dev] [PATCH 2/2] i965: Allocate URB space for HS and DS stages when required.

Kristian Høgsberg hoegsberg at gmail.com
Mon Dec 14 15:04:48 PST 2015


Kenneth Graunke <kenneth at whitecape.org> writes:

> From: Chris Forbes <chrisf at ijw.co.nz>
>
> v2: (by Ken, incorporating feedback from Matt Turner):
> - Rewrite the push constant allocation code to be clearer.
> - Only apply the minimum VS entries workaround on Gen 8.
>
> v3: (by Ken)
> - Fix a bug in v2 where we failed to allocate the full push constant
>   space when the number of enabled stages didn't divide the available
>   push constant space evenly.  (Any left over space is now allocated
>   to the PS, as it was in v1.)
> - Fix an off-by-one error in v2's number of enabled stages calculation.
> - Use DIV_ROUND_UP for nicer formatting.
> - Line wrapping fixes.
>
> Signed-off-by: Chris Forbes <chrisf at ijw.co.nz>
> Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
> ---
>  src/mesa/drivers/dri/i965/brw_context.h  |  21 +++-
>  src/mesa/drivers/dri/i965/gen7_blorp.cpp |   8 ++
>  src/mesa/drivers/dri/i965/gen7_urb.c     | 177 +++++++++++++++++++++++++------
>  3 files changed, 170 insertions(+), 36 deletions(-)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_context.h b/src/mesa/drivers/dri/i965/brw_context.h
> index 1cc4c7b..69bc04c 100644
> --- a/src/mesa/drivers/dri/i965/brw_context.h
> +++ b/src/mesa/drivers/dri/i965/brw_context.h
> @@ -1008,6 +1008,8 @@ struct brw_context
>     struct {
>        GLuint vsize;		/* vertex size plus header in urb registers */
>        GLuint gsize;	        /* GS output size in urb registers */
> +      GLuint hsize;             /* Tessellation control output size in urb registers */
> +      GLuint dsize;             /* Tessellation evaluation output size in urb registers */
>        GLuint csize;		/* constant buffer size in urb registers */
>        GLuint sfsize;		/* setup data size in urb registers */
>  
> @@ -1020,12 +1022,16 @@ struct brw_context
>        GLuint max_gs_entries;	/* Maximum number of GS entries */
>  
>        GLuint nr_vs_entries;
> +      GLuint nr_hs_entries;
> +      GLuint nr_ds_entries;
>        GLuint nr_gs_entries;
>        GLuint nr_clip_entries;
>        GLuint nr_sf_entries;
>        GLuint nr_cs_entries;
>  
>        GLuint vs_start;
> +      GLuint hs_start;
> +      GLuint ds_start;
>        GLuint gs_start;
>        GLuint clip_start;
>        GLuint sf_start;
> @@ -1042,6 +1048,11 @@ struct brw_context
>         * URB space for the GS.
>         */
>        bool gs_present;
> +
> +      /* True if the most recently sent _3DSTATE_URB message allocated
> +       * URB space for the HS and DS.
> +       */
> +      bool tess_present;
>     } urb;
>  
>  
> @@ -1648,12 +1659,18 @@ void gen8_emit_3dstate_sample_pattern(struct brw_context *brw);
>  /* gen7_urb.c */
>  void
>  gen7_emit_push_constant_state(struct brw_context *brw, unsigned vs_size,
> +                              unsigned hs_size, unsigned ds_size,
>                                unsigned gs_size, unsigned fs_size);
>  
>  void
>  gen7_emit_urb_state(struct brw_context *brw,
> -                    unsigned nr_vs_entries, unsigned vs_size,
> -                    unsigned vs_start, unsigned nr_gs_entries,
> +                    unsigned nr_vs_entries,
> +                    unsigned vs_size, unsigned vs_start,
> +                    unsigned nr_hs_entries,
> +                    unsigned hs_size, unsigned hs_start,
> +                    unsigned nr_ds_entries,
> +                    unsigned ds_size, unsigned ds_start,
> +                    unsigned nr_gs_entries,
>                      unsigned gs_size, unsigned gs_start);
>  
>  
> diff --git a/src/mesa/drivers/dri/i965/gen7_blorp.cpp b/src/mesa/drivers/dri/i965/gen7_blorp.cpp
> index e87b9d1..89b73ca 100644
> --- a/src/mesa/drivers/dri/i965/gen7_blorp.cpp
> +++ b/src/mesa/drivers/dri/i965/gen7_blorp.cpp
> @@ -50,6 +50,8 @@ gen7_blorp_emit_urb_config(struct brw_context *brw)
>     unsigned urb_size = (brw->is_haswell && brw->gt == 3) ? 32 : 16;
>     gen7_emit_push_constant_state(brw,
>                                   urb_size / 2 /* vs_size */,
> +                                 0 /* hs_size */,
> +                                 0 /* ds_size */,
>                                   0 /* gs_size */,
>                                   urb_size / 2 /* fs_size */);
>  
> @@ -60,6 +62,12 @@ gen7_blorp_emit_urb_config(struct brw_context *brw)
>                         32 /* num_vs_entries */,
>                         2 /* vs_size */,
>                         2 /* vs_start */,
> +                       0 /* num_hs_entries */,
> +                       1 /* hs_size */,
> +                       2 /* hs_start */,
> +                       0 /* num_ds_entries */,
> +                       1 /* ds_size */,
> +                       2 /* ds_start */,
>                         0 /* num_gs_entries */,
>                         1 /* gs_size */,
>                         2 /* gs_start */);
> diff --git a/src/mesa/drivers/dri/i965/gen7_urb.c b/src/mesa/drivers/dri/i965/gen7_urb.c
> index 421512b..f2b6ec3 100644
> --- a/src/mesa/drivers/dri/i965/gen7_urb.c
> +++ b/src/mesa/drivers/dri/i965/gen7_urb.c
> @@ -34,7 +34,7 @@
>   *   __________-__________   _________________-_________________
>   *  /                     \ /                                   \
>   * +-------------------------------------------------------------+
> - * |     VS/FS/GS Push     |              VS/GS URB              |
> + * |  VS/HS/DS/GS/FS Push  |           VS/HS/DS/GS URB           |
>   * |       Constants       |               Entries               |
>   * +-------------------------------------------------------------+
>   *
> @@ -60,27 +60,32 @@
>  static void
>  gen7_allocate_push_constants(struct brw_context *brw)
>  {
> +   /* BRW_NEW_GEOMETRY_PROGRAM */
> +   bool gs_present = brw->geometry_program;
> +
> +   /* BRW_NEW_TESS_CTRL_PROGRAM, BRW_NEW_TESS_EVAL_PROGRAM */
> +   bool tess_present = brw->tess_eval_program;
> +
>     unsigned avail_size = 16;
>     unsigned multiplier =
>        (brw->gen >= 8 || (brw->is_haswell && brw->gt == 3)) ? 2 : 1;
>  
> -   /* BRW_NEW_GEOMETRY_PROGRAM */
> -   bool gs_present = brw->geometry_program;
> +   int stages = 2 + gs_present + 2 * tess_present;
>  
> -   unsigned vs_size, gs_size;
> -   if (gs_present) {
> -      vs_size = avail_size / 3;
> -      avail_size -= vs_size;
> -      gs_size = avail_size / 2;
> -      avail_size -= gs_size;
> -   } else {
> -      vs_size = avail_size / 2;
> -      avail_size -= vs_size;
> -      gs_size = 0;
> -   }
> -   unsigned fs_size = avail_size;
> +   /* Divide up the available space equally between stages.  Because we
> +    * round down (using floor division), there may be some left over
> +    * space.  We allocate that to the pixel shader stage.
> +    */
> +   unsigned size_per_stage = avail_size / stages;
> +
> +   unsigned vs_size = size_per_stage;
> +   unsigned hs_size = tess_present ? size_per_stage : 0;
> +   unsigned ds_size = tess_present ? size_per_stage : 0;
> +   unsigned gs_size = gs_present ? size_per_stage : 0;
> +   unsigned fs_size = avail_size - size_per_stage * (stages - 1);

This is a lot nicer.

On the whole, patch looks good, straightforward extension of our current
heustics.

Reviewed-by: Kristian Høgsberg <krh at bitplanet.net>

>     gen7_emit_push_constant_state(brw, multiplier * vs_size,
> +                                 multiplier * hs_size, multiplier * ds_size,
>                                   multiplier * gs_size, multiplier * fs_size);
>  
>     /* From p115 of the Ivy Bridge PRM (3.2.1.4 3DSTATE_PUSH_CONSTANT_ALLOC_VS):
> @@ -99,15 +104,24 @@ gen7_allocate_push_constants(struct brw_context *brw)
>  
>  void
>  gen7_emit_push_constant_state(struct brw_context *brw, unsigned vs_size,
> +                              unsigned hs_size, unsigned ds_size,
>                                unsigned gs_size, unsigned fs_size)
>  {
>     unsigned offset = 0;
>  
> -   BEGIN_BATCH(6);
> +   BEGIN_BATCH(10);
>     OUT_BATCH(_3DSTATE_PUSH_CONSTANT_ALLOC_VS << 16 | (2 - 2));
>     OUT_BATCH(vs_size | offset << GEN7_PUSH_CONSTANT_BUFFER_OFFSET_SHIFT);
>     offset += vs_size;
>  
> +   OUT_BATCH(_3DSTATE_PUSH_CONSTANT_ALLOC_HS << 16 | (2 - 2));
> +   OUT_BATCH(hs_size | offset << GEN7_PUSH_CONSTANT_BUFFER_OFFSET_SHIFT);
> +   offset += hs_size;
> +
> +   OUT_BATCH(_3DSTATE_PUSH_CONSTANT_ALLOC_DS << 16 | (2 - 2));
> +   OUT_BATCH(ds_size | offset << GEN7_PUSH_CONSTANT_BUFFER_OFFSET_SHIFT);
> +   offset += ds_size;
> +
>     OUT_BATCH(_3DSTATE_PUSH_CONSTANT_ALLOC_GS << 16 | (2 - 2));
>     OUT_BATCH(gs_size | offset << GEN7_PUSH_CONSTANT_BUFFER_OFFSET_SHIFT);
>     offset += gs_size;
> @@ -130,7 +144,10 @@ gen7_emit_push_constant_state(struct brw_context *brw, unsigned vs_size,
>  const struct brw_tracked_state gen7_push_constant_space = {
>     .dirty = {
>        .mesa = 0,
> -      .brw = BRW_NEW_CONTEXT | BRW_NEW_GEOMETRY_PROGRAM,
> +      .brw = BRW_NEW_CONTEXT |
> +             BRW_NEW_GEOMETRY_PROGRAM |
> +             BRW_NEW_TESS_CTRL_PROGRAM |
> +             BRW_NEW_TESS_EVAL_PROGRAM,
>     },
>     .emit = gen7_allocate_push_constants,
>  };
> @@ -138,6 +155,7 @@ const struct brw_tracked_state gen7_push_constant_space = {
>  static void
>  gen7_upload_urb(struct brw_context *brw)
>  {
> +   const struct brw_device_info *devinfo = brw->intelScreen->devinfo;
>     const int push_size_kB =
>        (brw->gen >= 8 || (brw->is_haswell && brw->gt == 3)) ? 32 : 16;
>  
> @@ -149,6 +167,16 @@ gen7_upload_urb(struct brw_context *brw)
>     unsigned gs_size = gs_present ? brw->gs.prog_data->base.urb_entry_size : 1;
>     unsigned gs_entry_size_bytes = gs_size * 64;
>  
> +   /* BRW_NEW_TESS_CTRL_PROGRAM, BRW_NEW_TESS_EVAL_PROGRAM */
> +   const bool tess_present = brw->tess_eval_program;
> +   assert(!tess_present || brw->tess_ctrl_program);
> +   /* BRW_NEW_TCS_PROG_DATA */
> +   unsigned hs_size = tess_present ? brw->tcs.prog_data->base.urb_entry_size : 1;
> +   unsigned hs_entry_size_bytes = hs_size * 64;
> +   /* BRW_NEW_TES_PROG_DATA */
> +   unsigned ds_size = tess_present ? brw->tes.prog_data->base.urb_entry_size : 1;
> +   unsigned ds_entry_size_bytes = ds_size * 64;
> +
>     /* If we're just switching between programs with the same URB requirements,
>      * skip the rest of the logic.
>      */
> @@ -156,21 +184,29 @@ gen7_upload_urb(struct brw_context *brw)
>         !(brw->ctx.NewDriverState & BRW_NEW_URB_SIZE) &&
>         brw->urb.vsize == vs_size &&
>         brw->urb.gs_present == gs_present &&
> -       brw->urb.gsize == gs_size) {
> +       brw->urb.gsize == gs_size &&
> +       brw->urb.tess_present == tess_present &&
> +       brw->urb.hsize == hs_size &&
> +       brw->urb.dsize == ds_size) {
>        return;
>     }
>     brw->urb.vsize = vs_size;
>     brw->urb.gs_present = gs_present;
>     brw->urb.gsize = gs_size;
> +   brw->urb.tess_present = tess_present;
> +   brw->urb.hsize = hs_size;
> +   brw->urb.dsize = ds_size;
>  
>     /* From p35 of the Ivy Bridge PRM (section 1.7.1: 3DSTATE_URB_GS):
>      *
>      *     VS Number of URB Entries must be divisible by 8 if the VS URB Entry
>      *     Allocation Size is less than 9 512-bit URB entries.
>      *
> -    * Similar text exists for GS.
> +    * Similar text exists for HS, DS and GS.
>      */
>     unsigned vs_granularity = (vs_size < 9) ? 8 : 1;
> +   unsigned hs_granularity = (hs_size < 9) ? 8 : 1;
> +   unsigned ds_granularity = (ds_size < 9) ? 8 : 1;
>     unsigned gs_granularity = (gs_size < 9) ? 8 : 1;
>  
>     /* URB allocations must be done in 8k chunks. */
> @@ -191,10 +227,17 @@ gen7_upload_urb(struct brw_context *brw)
>      * additional space it could actually make use of).
>      */
>  
> -   /* VS has a lower limit on the number of URB entries */
> +   /* VS has a lower limit on the number of URB entries.
> +    *
> +    * From the Broadwell PRM, 3DSTATE_URB_VS instruction:
> +    * "When tessellation is enabled, the VS Number of URB Entries must be
> +    *  greater than or equal to 192."
> +    */
> +   unsigned vs_min_entries =
> +      tess_present && brw->gen == 8 ? 192 : brw->urb.min_vs_entries;
> +
>     unsigned vs_chunks =
> -      DIV_ROUND_UP(brw->urb.min_vs_entries * vs_entry_size_bytes,
> -                   chunk_size_bytes);
> +      DIV_ROUND_UP(vs_min_entries * vs_entry_size_bytes, chunk_size_bytes);
>     unsigned vs_wants =
>        DIV_ROUND_UP(brw->urb.max_vs_entries * vs_entry_size_bytes,
>                     chunk_size_bytes) - vs_chunks;
> @@ -216,14 +259,36 @@ gen7_upload_urb(struct brw_context *brw)
>                                chunk_size_bytes) - gs_chunks;
>     }
>  
> +   unsigned hs_chunks = 0;
> +   unsigned hs_wants = 0;
> +   unsigned ds_chunks = 0;
> +   unsigned ds_wants = 0;
> +
> +   if (tess_present) {
> +      hs_chunks =
> +         DIV_ROUND_UP(hs_granularity * hs_entry_size_bytes,
> +                      chunk_size_bytes);
> +      hs_wants =
> +         DIV_ROUND_UP(devinfo->urb.max_hs_entries * hs_entry_size_bytes,
> +                      chunk_size_bytes) - hs_chunks;
> +
> +      ds_chunks =
> +         DIV_ROUND_UP(devinfo->urb.min_ds_entries * ds_entry_size_bytes,
> +                      chunk_size_bytes);
> +      ds_wants =
> +         DIV_ROUND_UP(brw->urb.max_ds_entries * ds_entry_size_bytes,
> +                      chunk_size_bytes) - ds_chunks;
> +   }
> +
>     /* There should always be enough URB space to satisfy the minimum
>      * requirements of each stage.
>      */
> -   unsigned total_needs = push_constant_chunks + vs_chunks + gs_chunks;
> +   unsigned total_needs = push_constant_chunks +
> +                          vs_chunks + hs_chunks + ds_chunks + gs_chunks;
>     assert(total_needs <= urb_chunks);
>  
>     /* Mete out remaining space (if any) in proportion to "wants". */
> -   unsigned total_wants = vs_wants + gs_wants;
> +   unsigned total_wants = vs_wants + hs_wants + ds_wants + gs_wants;
>     unsigned remaining_space = urb_chunks - total_needs;
>     if (remaining_space > total_wants)
>        remaining_space = total_wants;
> @@ -232,61 +297,100 @@ gen7_upload_urb(struct brw_context *brw)
>           roundf(vs_wants * (((float) remaining_space) / total_wants));
>        vs_chunks += vs_additional;
>        remaining_space -= vs_additional;
> +      total_wants -= vs_wants;
> +
> +      unsigned hs_additional = (unsigned)
> +         round(hs_wants * (((double) remaining_space) / total_wants));
> +      hs_chunks += hs_additional;
> +      remaining_space -= hs_additional;
> +      total_wants -= hs_wants;
> +
> +      unsigned ds_additional = (unsigned)
> +         round(ds_wants * (((double) remaining_space) / total_wants));
> +      ds_chunks += ds_additional;
> +      remaining_space -= ds_additional;
> +      total_wants -= ds_wants;
> +
>        gs_chunks += remaining_space;
>     }
>  
>     /* Sanity check that we haven't over-allocated. */
> -   assert(push_constant_chunks + vs_chunks + gs_chunks <= urb_chunks);
> +   assert(push_constant_chunks +
> +          vs_chunks + hs_chunks + ds_chunks + gs_chunks <= urb_chunks);
>  
>     /* Finally, compute the number of entries that can fit in the space
>      * allocated to each stage.
>      */
>     unsigned nr_vs_entries = vs_chunks * chunk_size_bytes / vs_entry_size_bytes;
> +   unsigned nr_hs_entries = hs_chunks * chunk_size_bytes / hs_entry_size_bytes;
> +   unsigned nr_ds_entries = ds_chunks * chunk_size_bytes / ds_entry_size_bytes;
>     unsigned nr_gs_entries = gs_chunks * chunk_size_bytes / gs_entry_size_bytes;
>  
>     /* Since we rounded up when computing *_wants, this may be slightly more
>      * than the maximum allowed amount, so correct for that.
>      */
>     nr_vs_entries = MIN2(nr_vs_entries, brw->urb.max_vs_entries);
> +   nr_hs_entries = MIN2(nr_hs_entries, brw->urb.max_hs_entries);
> +   nr_ds_entries = MIN2(nr_ds_entries, brw->urb.max_ds_entries);
>     nr_gs_entries = MIN2(nr_gs_entries, brw->urb.max_gs_entries);
>  
>     /* Ensure that we program a multiple of the granularity. */
>     nr_vs_entries = ROUND_DOWN_TO(nr_vs_entries, vs_granularity);
> +   nr_hs_entries = ROUND_DOWN_TO(nr_hs_entries, hs_granularity);
> +   nr_ds_entries = ROUND_DOWN_TO(nr_ds_entries, ds_granularity);
>     nr_gs_entries = ROUND_DOWN_TO(nr_gs_entries, gs_granularity);
>  
>     /* Finally, sanity check to make sure we have at least the minimum number
>      * of entries needed for each stage.
>      */
> -   assert(nr_vs_entries >= brw->urb.min_vs_entries);
> +   assert(nr_vs_entries >= vs_min_entries);
>     if (gs_present)
>        assert(nr_gs_entries >= 2);
> +   if (tess_present) {
> +      assert(nr_hs_entries >= 1);
> +      assert(nr_ds_entries >= devinfo->urb.min_ds_entries);
> +   }
>  
>     /* Gen7 doesn't actually use brw->urb.nr_{vs,gs}_entries, but it seems
>      * better to put reasonable data in there rather than leave them
>      * uninitialized.
>      */
>     brw->urb.nr_vs_entries = nr_vs_entries;
> +   brw->urb.nr_hs_entries = nr_hs_entries;
> +   brw->urb.nr_ds_entries = nr_ds_entries;
>     brw->urb.nr_gs_entries = nr_gs_entries;
>  
>     /* Lay out the URB in the following order:
>      * - push constants
>      * - VS
> +    * - HS
> +    * - DS
>      * - GS
>      */
>     brw->urb.vs_start = push_constant_chunks;
> -   brw->urb.gs_start = push_constant_chunks + vs_chunks;
> +   brw->urb.hs_start = push_constant_chunks + vs_chunks;
> +   brw->urb.ds_start = push_constant_chunks + vs_chunks + hs_chunks;
> +   brw->urb.gs_start = push_constant_chunks + vs_chunks + hs_chunks +
> +                       ds_chunks;
>  
>     if (brw->gen == 7 && !brw->is_haswell && !brw->is_baytrail)
>        gen7_emit_vs_workaround_flush(brw);
>     gen7_emit_urb_state(brw,
>                         brw->urb.nr_vs_entries, vs_size, brw->urb.vs_start,
> +                       brw->urb.nr_hs_entries, hs_size, brw->urb.hs_start,
> +                       brw->urb.nr_ds_entries, ds_size, brw->urb.ds_start,
>                         brw->urb.nr_gs_entries, gs_size, brw->urb.gs_start);
>  }
>  
>  void
>  gen7_emit_urb_state(struct brw_context *brw,
> -                    unsigned nr_vs_entries, unsigned vs_size,
> -                    unsigned vs_start, unsigned nr_gs_entries,
> +                    unsigned nr_vs_entries,
> +                    unsigned vs_size, unsigned vs_start,
> +                    unsigned nr_hs_entries,
> +                    unsigned hs_size, unsigned hs_start,
> +                    unsigned nr_ds_entries,
> +                    unsigned ds_size, unsigned ds_start,
> +                    unsigned nr_gs_entries,
>                      unsigned gs_size, unsigned gs_start)
>  {
>     BEGIN_BATCH(8);
> @@ -300,14 +404,15 @@ gen7_emit_urb_state(struct brw_context *brw,
>               ((gs_size - 1) << GEN7_URB_ENTRY_SIZE_SHIFT) |
>               (gs_start << GEN7_URB_STARTING_ADDRESS_SHIFT));
>  
> -   /* Allocate the HS and DS zero space - we don't use them. */
>     OUT_BATCH(_3DSTATE_URB_HS << 16 | (2 - 2));
> -   OUT_BATCH((0 << GEN7_URB_ENTRY_SIZE_SHIFT) |
> -             (vs_start << GEN7_URB_STARTING_ADDRESS_SHIFT));
> +   OUT_BATCH(nr_hs_entries |
> +             ((hs_size - 1) << GEN7_URB_ENTRY_SIZE_SHIFT) |
> +             (hs_start << GEN7_URB_STARTING_ADDRESS_SHIFT));
>  
>     OUT_BATCH(_3DSTATE_URB_DS << 16 | (2 - 2));
> -   OUT_BATCH((0 << GEN7_URB_ENTRY_SIZE_SHIFT) |
> -             (vs_start << GEN7_URB_STARTING_ADDRESS_SHIFT));
> +   OUT_BATCH(nr_ds_entries |
> +             ((ds_size - 1) << GEN7_URB_ENTRY_SIZE_SHIFT) |
> +             (ds_start << GEN7_URB_STARTING_ADDRESS_SHIFT));
>     ADVANCE_BATCH();
>  }
>  
> @@ -317,7 +422,11 @@ const struct brw_tracked_state gen7_urb = {
>        .brw = BRW_NEW_CONTEXT |
>               BRW_NEW_URB_SIZE |
>               BRW_NEW_GEOMETRY_PROGRAM |
> +             BRW_NEW_TESS_CTRL_PROGRAM |
> +             BRW_NEW_TESS_EVAL_PROGRAM |
>               BRW_NEW_GS_PROG_DATA |
> +             BRW_NEW_TCS_PROG_DATA |
> +             BRW_NEW_TES_PROG_DATA |
>               BRW_NEW_VS_PROG_DATA,
>     },
>     .emit = gen7_upload_urb,
> -- 
> 2.6.3
>
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