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ZachBethel

DX12 ID3D12Device::GetResourceAllocationInfo

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Hey,

I'm working on a placed resource system, and I need a way to determine the size and alignement of image resources before placing them on the heap. This is used for transient resources within a frame. The appropriate method on ID3D12Device is GetResourceAllocationInfo. Unfortunately, this method is quite slow and eats up a pretty significant chunk of time. Way more than I would expect for just returning a size and alignment (I'm using a single D3D12_RESOURCE_DESC) each time.

Is there a way I can conservatively estimate this value for certain texture resources (i.e. ones without mip chains or something)?

Thanks.

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1 hour ago, ZachBethel said:

Is there a way I can conservatively estimate this value for certain texture resources (i.e. ones without mip chains or something)?

I don't think so.

Can't you call it once for each type of transient resource, and then reuse the results every frame (instead of re-calling it every frame with the same inputs)?

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That's what I thought. The solution I went with is to keep a map of image descriptor hash to resource allocation info. It cut down on the cost by 3x. Thanks!

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10 hours ago, ZachBethel said:

That's what I thought. The solution I went with is to keep a map of image descriptor hash to resource allocation info. It cut down on the cost by 3x. Thanks!

You probably mean an hash table ? You can also populate the most common cases at the init in a flat structure for better cache coherency. But does this really matters ?

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