[Mesa-dev] [PATCH 1/2] i965: add missing rollback of URB requirements

[Lionel Landwerlin]

Hi Andrii,

Although I think what these patches do makes sense, I think it's missing 
the bigger picture.
There is a lot more state that gets lost if we have to revert all of the 
emitted commands.
A quick look at brw_upload_pipeline_state() shows all of the programs 
could be invalid as well, or the number of samples, etc...

To me it seems like we need a much larger state save/restore.

Ken: what do you think?

Cheers,

-
Lionel

On 19/11/2018 21:19, asimiklit.work at gmail.com wrote:
> From: Andrii Simiklit <andrii.simiklit at globallogic.com>
>
> This patch is needed to avoid missing 3DSTATE_URB_* commands in a batch after
> rollback operation.
>
> To be able to test easily this issue
> the following workaround is necessary:
> -if (!brw_batch_has_aperture_space(brw, 0)) {
> by:
> +if (true) {
> in brw_draw_single_prim function.
>
> This workaround forces a rollback for each batch.
> The "gl-3.2-adj-prims pv-first -auto -fbo" piglit test with this workaround
> led to a hung. The hung investigation helped to find that some batches
> didn't have the 3DSTATE_URB_* commands in compare to batches which were
> generated without this workaround.
>
> Reported-by: Kenneth Graunke <kenneth at whitecape.org>
> Signed-off-by: Andrii Simiklit <andrii.simiklit at globallogic.com>
> ---
>   src/mesa/drivers/dri/i965/brw_context.h       |  8 ++++++++
>   src/mesa/drivers/dri/i965/intel_batchbuffer.c | 12 ++++++++++++
>   2 files changed, 20 insertions(+)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_context.h b/src/mesa/drivers/dri/i965/brw_context.h
> index 7fd15669eb..4e1682ba5c 100644
> --- a/src/mesa/drivers/dri/i965/brw_context.h
> +++ b/src/mesa/drivers/dri/i965/brw_context.h
> @@ -521,6 +521,14 @@ struct intel_batchbuffer {
>         int batch_reloc_count;
>         int state_reloc_count;
>         int exec_count;
> +      struct {
> +         GLuint vsize;
> +         GLuint gsize;
> +         GLuint hsize;
> +         GLuint dsize;
> +         bool gs_present;
> +         bool tess_present;
> +      } urb;
>      } saved;
>   
>      /** Map from batch offset to brw_state_batch data (with DEBUG_BATCH) */
> diff --git a/src/mesa/drivers/dri/i965/intel_batchbuffer.c b/src/mesa/drivers/dri/i965/intel_batchbuffer.c
> index 353fcba18f..bae9f2ffed 100644
> --- a/src/mesa/drivers/dri/i965/intel_batchbuffer.c
> +++ b/src/mesa/drivers/dri/i965/intel_batchbuffer.c
> @@ -299,6 +299,12 @@ intel_batchbuffer_save_state(struct brw_context *brw)
>      brw->batch.saved.batch_reloc_count = brw->batch.batch_relocs.reloc_count;
>      brw->batch.saved.state_reloc_count = brw->batch.state_relocs.reloc_count;
>      brw->batch.saved.exec_count = brw->batch.exec_count;
> +   brw->batch.saved.urb.vsize = brw->urb.vsize;
> +   brw->batch.saved.urb.gs_present = brw->urb.gs_present;
> +   brw->batch.saved.urb.gsize = brw->urb.gsize;
> +   brw->batch.saved.urb.tess_present = brw->urb.tess_present;
> +   brw->batch.saved.urb.hsize = brw->urb.hsize;
> +   brw->batch.saved.urb.dsize = brw->urb.dsize;
>   }
>   
>   void
> @@ -313,6 +319,12 @@ intel_batchbuffer_reset_to_saved(struct brw_context *brw)
>      brw->batch.exec_count = brw->batch.saved.exec_count;
>   
>      brw->batch.map_next = brw->batch.saved.map_next;
> +   brw->urb.vsize = brw->batch.saved.urb.vsize;
> +   brw->urb.gs_present = brw->batch.saved.urb.gs_present;
> +   brw->urb.gsize = brw->batch.saved.urb.gsize;
> +   brw->urb.tess_present = brw->batch.saved.urb.tess_present;
> +   brw->urb.hsize = brw->batch.saved.urb.hsize;
> +   brw->urb.dsize = brw->batch.saved.urb.dsize;
>      if (USED_BATCH(brw->batch) == 0)
>         brw_new_batch(brw);
>   }