Edit

Hardware Tiers

  • Article

The levels of hardware from Tier 1 to Tier 3 have increasing resources available to the pipeline.

Limits dependant on hardware

Resources Available to the Pipeline Tier 1 Tier 2 Tier 3
Feature levels 11.0+ 11.0+ 11.1+
Maximum number of descriptors in a Constant Buffer View (CBV), Shader Resource View (SRV), or Unordered Access View(UAV) heap used for rendering 1,000,000 1,000,000 1,000,000+
Maximum number of Constant Buffer Views in all descriptor tables per shader stage 14 14 full heap
Maximum number of Shader Resource Views in all descriptor tables per shader stage 128 full heap full heap
Maximum number of Unordered Access Views in all descriptor tables across all stages 64 for feature levels 11.1+
8 for feature level 11
 64 full heap
Maximum number of Samplers in all descriptor tables per shader stage 16 2048 2048

Bold entries highlight significant improvements over the previous tier.

There is an additional restriction for Tier 1 hardware that applies to all heaps, and to Tier 2 hardware that applies to CBV and UAV heaps, that all descriptor heap entries covered by descriptor tables in the root signature must be populated with descriptors by the time the shader executes, even if the shader (perhaps due to branching) does not need the descriptor. There is no such restriction for Tier 3 hardware. One mitigation for this restriction is the diligent use of Null descriptors.

Invariable limits

The maximum number of samplers in a shader visible descriptor heap is 2048.

The maximum number of unique static samplers across live root signatures is 2032 (which leaves 16 for drivers that need their own samplers).

Descriptor Heaps

Hardware Feature Levels