[Mesa-dev] [PATCH 3/8] i965: Store the atoms directly in the context

[Jason Ekstrand]

I wrote basically this same patch when I was trying to speed up basically
the same test.  Unfortunately, I wasn't able to get much of an improvement
out of it.  Other than the one nit below,
Reviewed-by: Jason Ekstrand <jason.ekstrand at intel.com>

On Fri, Dec 19, 2014 at 2:20 PM, Ian Romanick <idr at freedesktop.org> wrote:
>
> From: Ian Romanick <ian.d.romanick at intel.com>
>
> Instead of having an extra pointer indirection in one of the hottest
> loops in the driver.
>
> On Bay Trail-D using Fedora 20 compile flags (-m64 -O2 -mtune=generic
> for 64-bit and -m32 -march=i686 -mtune=atom for 32-bit), affects
> Gl32Batch7:
>
> 32-bit: Difference at 95.0% confidence 1.98515% +/- 0.20814% (n=40)
> 64-bit: Difference at 95.0% confidence 1.5163% +/- 0.811016% (n=60)
>
> Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
> ---
>  src/mesa/drivers/dri/i965/brw_context.h      |  2 +-
>  src/mesa/drivers/dri/i965/brw_state_upload.c | 19 ++++++++++++++++---
>  2 files changed, 17 insertions(+), 4 deletions(-)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_context.h
> b/src/mesa/drivers/dri/i965/brw_context.h
> index 92eb022..5f5f807 100644
> --- a/src/mesa/drivers/dri/i965/brw_context.h
> +++ b/src/mesa/drivers/dri/i965/brw_context.h
> @@ -1384,7 +1384,7 @@ struct brw_context
>     } perfmon;
>
>     int num_atoms;
> -   const struct brw_tracked_state **atoms;
> +   const struct brw_tracked_state atoms[64];
>

Maybe a #define?


>
>     /* If (INTEL_DEBUG & DEBUG_BATCH) */
>     struct {
> diff --git a/src/mesa/drivers/dri/i965/brw_state_upload.c
> b/src/mesa/drivers/dri/i965/brw_state_upload.c
> index a579781..9a5d49a 100644
> --- a/src/mesa/drivers/dri/i965/brw_state_upload.c
> +++ b/src/mesa/drivers/dri/i965/brw_state_upload.c
> @@ -357,6 +357,11 @@ void brw_init_state( struct brw_context *brw )
>     const struct brw_tracked_state **atoms;
>     int num_atoms;
>
> +   STATIC_ASSERT(ARRAY_SIZE(gen4_atoms) <= ARRAY_SIZE(brw->atoms));
> +   STATIC_ASSERT(ARRAY_SIZE(gen6_atoms) <= ARRAY_SIZE(brw->atoms));
> +   STATIC_ASSERT(ARRAY_SIZE(gen7_atoms) <= ARRAY_SIZE(brw->atoms));
> +   STATIC_ASSERT(ARRAY_SIZE(gen8_atoms) <= ARRAY_SIZE(brw->atoms));
> +
>     brw_init_caches(brw);
>
>     if (brw->gen >= 8) {
> @@ -373,9 +378,17 @@ void brw_init_state( struct brw_context *brw )
>        num_atoms = ARRAY_SIZE(gen4_atoms);
>     }
>
> -   brw->atoms = atoms;
>     brw->num_atoms = num_atoms;
>
> +   /* This is to work around brw_context::atoms being declared const.  We
> want
> +    * it to be const, but it needs to be initialized somehow!
> +    */
> +   struct brw_tracked_state *context_atoms =
> +      (struct brw_tracked_state *) &brw->atoms[0];
> +
> +   for (int i = 0; i < num_atoms; i++)
> +      context_atoms[i] = *atoms[i];
> +
>     while (num_atoms--) {
>        assert((*atoms)->dirty.mesa | (*atoms)->dirty.brw);
>        assert((*atoms)->emit);
> @@ -607,7 +620,7 @@ void brw_upload_state(struct brw_context *brw)
>        prev = *state;
>
>        for (i = 0; i < brw->num_atoms; i++) {
> -        const struct brw_tracked_state *atom = brw->atoms[i];
> +        const struct brw_tracked_state *atom = &brw->atoms[i];
>          struct brw_state_flags generated;
>
>          if (check_state(state, &atom->dirty)) {
> @@ -627,7 +640,7 @@ void brw_upload_state(struct brw_context *brw)
>     }
>     else {
>        for (i = 0; i < brw->num_atoms; i++) {
> -        const struct brw_tracked_state *atom = brw->atoms[i];
> +        const struct brw_tracked_state *atom = &brw->atoms[i];
>
>          if (check_state(state, &atom->dirty)) {
>             atom->emit(brw);
> --
> 1.8.1.4
>
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