[Mesa-stable] [Mesa-dev] [PATCH] i965/tex: Don't pass samples to miptree_create_for_teximage

[Pohjolainen, Topi]

On Sat, Aug 19, 2017 at 11:07:35AM -0700, Jason Ekstrand wrote:
> In 76e2f390f9863a35, when Topi switched num_samples from 0 to 1 for
> single-sampled, he accidentally switched the last parameter in the call
> to miptree_create_for_teximage from 0 to 1 thinking it was num_samples
> when it was actually layout_flags.  Switching from 0 to 1 added the
> MIPTREE_LAYOUT_ACCELERATED_UPLOAD flag which causes us to allocate a
> busy BO instead of an idle one.  This caused the subsequent CPU upload
> to consistently stall.  The end result was a 15% performance drop in the
> SynMark v7 DrvRes microbenchmark.  This restores the old behavior and
> fixes the performance regression.

Oh man :(, huge thanks for tracking this down:

Reviewed-by: Topi Pohjolainen <topi.pohjolainen at intel.com>

> 
> Cc: Kenneth Graunke <kenneth at whitecape.org>
> Cc: Topi Pohjolainen <topi.pohjolainen at intel.com>
> Fixes: 76e2f390f9863a356d1419982dec705260d67eff
> Bugzilla: https://bugs.freedesktop.org/102260
> Cc: mesa-stable at lists.freedesktop.org
> ---
>  src/mesa/drivers/dri/i965/intel_tex.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/src/mesa/drivers/dri/i965/intel_tex.c b/src/mesa/drivers/dri/i965/intel_tex.c
> index 890c82d..94a7ad3 100644
> --- a/src/mesa/drivers/dri/i965/intel_tex.c
> +++ b/src/mesa/drivers/dri/i965/intel_tex.c
> @@ -94,7 +94,7 @@ intel_alloc_texture_image_buffer(struct gl_context *ctx,
>     } else {
>        intel_image->mt = intel_miptree_create_for_teximage(brw, intel_texobj,
>                                                            intel_image,
> -                                                          1 /* samples */);
> +                                                          MIPTREE_CREATE_DEFAULT);
>        if (!intel_image->mt)
>           return false;
>  
> -- 
> 2.5.0.400.gff86faf
> 
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