The Sampler 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.
This metric is unreliable when protected HD media content is being played back on a system with Intel® HD Graphics 5000/ 4600 / 4400 / 4200, Intel® Iris™ graphics 5100, or Intel® Iris™ Pro graphics 5200 configuration.
If Sampler 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 Graphics Frame Analyzer, and try one or more of the following techniques:
- the 2x2 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
This metric might show incorrect results and will be disabled with the next driver update.