[PATCH vkd3d 01/13] vkd3d: Store view properties in vkd3d_view.

Philip Rebohle philip.rebohle at tu-dortmund.de
Tue Nov 12 03:28:16 CST 2019

Storing the Vulkan view handle in the descriptor should still work with 
this if it's useful for descriptor updates (in fact it can even be done 
without increasing the descriptor size since the VkDescriptorBufferInfo 
struct in the union pushes the whole thing to 32 bytes anyway), but the 
previous implementation stored a lot of data in the descriptor that 
wasn't really needed at all most of the time. ClearUAV and friends are 
rare and heavy enough that, dereferencing the view pointer really isn't 
a performance concern at all.

Am 12.11.19 um 05:19 schrieb Conor McCarthy:
> On Tue, Nov 12, 2019 at 2:40 AM Philip Rebohle 
> <philip.rebohle at tu-dortmund.de <mailto:philip.rebohle at tu-dortmund.de>> 
> wrote:
>     Moving this out of d3d12_desc also helps make copying and
>     traversing descriptor arrays more CPU cache-friendly.
> Making descriptors smaller would help, but the most likely cause of a 
> cache miss is accessing two objects located far apart in memory. Reading 
> data from a descriptor and then other data via a view pointer creates 
> this situation. I made a new version of the cache coherence patch which 
> eliminates use of vkd3d_view for CBV, SRV and UAV descriptors and only 
> stores a refcount on the heap, but haven't sent it because it conflicts 
> with a pending patch. It only gains 0.5% fps, so if new implementations 
> need an expanded view struct instead then that takes precedence. CPU 
> caching is worth taking into account though.
> Conor

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