[Mesa-dev] [v2 4/9] i965: Estimate batch space per shader stage

[Pohjolainen, Topi]

Sorry for the typo in the subject, this is version three.

On Tue, Feb 28, 2017 at 10:02:42AM +0200, Topi Pohjolainen wrote:
> Current estimate doesn't consider space needed for surface states
> and it only calculates for one shader stage. Each stage can have
> its own sampler and surface state configuration.
> 
> While this is only matter of runtime dynamics we don't seem to hit
> it currently. However, this becomes visible with blorp tex uploads
> (HSW with piglit test max-samplers). One runs out of space while
> batch wrapping isn't allowed.
> 
> v2: Rebase on top of current upstream
> v3: Take binding table alignment into account (Jason)
> 
> Signed-off-by: Topi Pohjolainen <topi.pohjolainen at intel.com>
> CC: Kenneth Graunke <kenneth at whitecape.org>
> CC: Jason Ekstrand <jason at jlekstrand.net>
> ---
>  src/mesa/drivers/dri/i965/brw_draw.c | 53 ++++++++++++++++++++++++++++++++++--
>  1 file changed, 50 insertions(+), 3 deletions(-)
> 
> diff --git a/src/mesa/drivers/dri/i965/brw_draw.c b/src/mesa/drivers/dri/i965/brw_draw.c
> index 6ca6a7a..dba8603 100644
> --- a/src/mesa/drivers/dri/i965/brw_draw.c
> +++ b/src/mesa/drivers/dri/i965/brw_draw.c
> @@ -395,6 +395,55 @@ brw_postdraw_set_buffers_need_resolve(struct brw_context *brw)
>     }
>  }
>  
> +static unsigned
> +brw_get_num_active_samplers(const struct gl_context *ctx,
> +                            const struct gl_program *prog)
> +{
> +   const unsigned last = util_last_bit(prog->SamplersUsed);
> +   unsigned count = 0;
> +
> +   for (unsigned s = 0; s < last; s++) {
> +      if (prog->SamplersUsed & (1 << s)) {
> +         const unsigned unit = prog->SamplerUnits[s];
> +         if (ctx->Texture.Unit[unit]._Current)
> +            ++count;
> +      }
> +   }
> +
> +   return count;
> +}
> +
> +static unsigned
> +brw_estimate_batch_space_for_textures(const struct brw_context *brw)
> +{
> +   const struct gl_context *ctx = &brw->ctx;
> +   unsigned total = 0;
> +
> +   for (unsigned i = 0; i < MESA_SHADER_STAGES; i++) {
> +      const struct gl_program *prog = ctx->_Shader->CurrentProgram[i];
> +
> +      if (prog == NULL)
> +         continue;
> +
> +      const unsigned num_samplers = brw_get_num_active_samplers(ctx, prog);
> +      const unsigned sampler_needs_per_tex_unit =
> +         16 /* sampler_state_size */ +
> +         sizeof(struct gen5_sampler_default_color);
> +      const unsigned surface_state_needs_per_tex_unit =
> +         ALIGN(brw->isl_dev.ss.size, brw->isl_dev.ss.align);
> +      const unsigned total_per_tex_unit = sampler_needs_per_tex_unit +
> +                                          surface_state_needs_per_tex_unit;
> +      total += (num_samplers * total_per_tex_unit);
> +
> +      /* Also consider space and alignment needed for binding table pointers,
> +       * each taking four bytes.
> +       */
> +      total += ALIGN(num_samplers * 4, 64);
> +   }
> +
> +   return total;
> +}
> +
>  /* May fail if out of video memory for texture or vbo upload, or on
>   * fallback conditions.
>   */
> @@ -466,11 +515,9 @@ brw_try_draw_prims(struct gl_context *ctx,
>  
>     for (i = 0; i < nr_prims; i++) {
>        int estimated_max_prim_size;
> -      const int sampler_state_size = 16;
>  
>        estimated_max_prim_size = 512; /* batchbuffer commands */
> -      estimated_max_prim_size += BRW_MAX_TEX_UNIT *
> -         (sampler_state_size + sizeof(struct gen5_sampler_default_color));
> +      estimated_max_prim_size += brw_estimate_batch_space_for_textures(brw);
>        estimated_max_prim_size += 1024; /* gen6 VS push constants */
>        estimated_max_prim_size += 1024; /* gen6 WM push constants */
>        estimated_max_prim_size += 512; /* misc. pad */
> -- 
> 2.9.3
>