Sampler Is Bottleneck
The Sampler Is Bottleneck metric represents the percentage of time that the texture sampler is a bottleneck. The sampler is stalling Execution Units (EUs) due to a full input FIFO and starving EUs due to a lack of results.
On Intel® HD Graphics 2500/4000: to access this metric, you must explicitly enable the Intel® Graphics Performance Analyzers option in your BIOS settings:
Select System Agent (SA) Configuration
Select Graphics Configuration
Reboot your machine
If the BIOS on your system does not include the Intel® Graphics Performance Analyzers option, update your BIOS to the latest version from Intel. After completing your performance monitoring activity, we recommend that you disable the Intel® Graphics Performance Analyzers BIOS option and reboot your machine.
If Sampler Is Bottleneck is 90, then the texture sampler is a bottleneck (stalling some EUs and/or causing other EUs to idle) 90% of the time.
The following techniques may improve the texture sampler performance:
- Reducing the size of textures, by using a lower resolution or lower color precision (such as RGBA4444 instead of RGBA8888)
- Using texture compression to reduce the amount of memory to transfer textures
- Using mipmapping, so that smaller textures (mipmaps) can be used
- Reducing the number of textures in the scene
- Using a different filtering algorithm
For example, anisotropic filtering is more expensive to compute than a simpler algorithm, such as bilinear filtering To help minimize overhead in this area, capture a typical frame while the game is running, use this frame as input to the Intel® GPA Frame Analyzer, and try one or more of the following techniques:
- the 2×2 Textures experiment in the Experiments tab to see if textures are a bottleneck
- the Texture tab to see the texture size, format, and mip level.