[Mesa-dev] [PATCH] i965: use nonblocking maps MapRangeBuffer

[Eric Anholt]

On Thu, 22 Sep 2011 16:27:12 -0700, Ben Widawsky <ben at bwidawsk.net> wrote:
> This makes the code a lot cleaner, and theoretically faster (not many
> real world tests use this GL extension).
> 
> Cc: Eric Anholt <eric at anholt.net>
> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> Cc: Mesa Devs <mesa-dev at lists.freedesktop.org>
> Signed-off-by: Ben Widawsky <ben at bwidawsk.net>
> ---
>  src/mesa/drivers/dri/intel/intel_buffer_objects.c |   48 ++------------------
>  1 files changed, 5 insertions(+), 43 deletions(-)
> 
> diff --git a/src/mesa/drivers/dri/intel/intel_buffer_objects.c b/src/mesa/drivers/dri/intel/intel_buffer_objects.c
> index d35a50e..91dddce 100644
> --- a/src/mesa/drivers/dri/intel/intel_buffer_objects.c
> +++ b/src/mesa/drivers/dri/intel/intel_buffer_objects.c
> @@ -296,8 +296,6 @@ intel_bufferobj_get_subdata(struct gl_context * ctx,
>     }
>  }
>  
> -
> -
>  /**
>   * Called via glMapBufferRange and glMapBuffer
>   *
> @@ -363,50 +361,14 @@ intel_bufferobj_map_range(struct gl_context * ctx,
>        return NULL;
>     }
>  
> -   /* If the user doesn't care about existing buffer contents and mapping
> -    * would cause us to block, then throw out the old buffer.
> -    */
> -   if (!(access & GL_MAP_UNSYNCHRONIZED_BIT) &&
> -       (access & GL_MAP_INVALIDATE_BUFFER_BIT) &&
> -       drm_intel_bo_busy(intel_obj->buffer)) {
> -      drm_intel_bo_unreference(intel_obj->buffer);
> -      intel_bufferobj_alloc_buffer(intel, intel_obj);
> -   }

Why did you delete this code?  Applications rely on this happening.

> -
> -   /* If the user is mapping a range of an active buffer object but
> -    * doesn't require the current contents of that range, make a new
> -    * BO, and we'll copy what they put in there out at unmap or
> -    * FlushRange time.
> -    */
>     if ((access & GL_MAP_INVALIDATE_RANGE_BIT) &&
> -       drm_intel_bo_busy(intel_obj->buffer)) {
> -      if (access & GL_MAP_FLUSH_EXPLICIT_BIT) {
> +       drm_intel_bo_busy(intel_obj->buffer) &&
> +       (access & GL_MAP_FLUSH_EXPLICIT_BIT)) {
>  	 intel_obj->range_map_buffer = malloc(length);
>  	 obj->Pointer = intel_obj->range_map_buffer;
> -      } else {
> -	 intel_obj->range_map_bo = drm_intel_bo_alloc(intel->bufmgr,
> -						      "range map",
> -						      length, 64);
> -	 if (!(access & GL_MAP_READ_BIT)) {
> -	    drm_intel_gem_bo_map_gtt(intel_obj->range_map_bo);
> -	    intel_obj->mapped_gtt = GL_TRUE;
> -	 } else {
> -	    drm_intel_bo_map(intel_obj->range_map_bo,
> -			     (access & GL_MAP_WRITE_BIT) != 0);
> -	    intel_obj->mapped_gtt = GL_FALSE;
> -	 }
> -	 obj->Pointer = intel_obj->range_map_bo->virtual;
> -      }
> -      return obj->Pointer;
> -   }
> -
> -   if (!(access & GL_MAP_READ_BIT)) {
> -      drm_intel_gem_bo_map_gtt(intel_obj->buffer);
> -      intel_obj->mapped_gtt = GL_TRUE;
> -   } else {
> -      drm_intel_bo_map(intel_obj->buffer, (access & GL_MAP_WRITE_BIT) != 0);
> -      intel_obj->mapped_gtt = GL_FALSE;
> -   }
> +	 return obj->Pointer;
> +   } else
> +    drm_intel_gem_bo_map_nonblocking(intel_obj->buffer, &intel_obj->mapped_gtt);

So, if either INVALIDATE or FLUSH_EXPLICIT is not set, or the buffer is
idle, you use the nonblocking map instead of the normal blocking map?
How is that supposed to be correct?

This patch should be adding one new case and an early return.  If it
does something else, that's a bad sign.

>     obj->Pointer = intel_obj->buffer->virtual + offset;
>     return obj->Pointer;
> -- 
> 1.7.6.3
> 
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