The Samplers Busy metric represents the percentage of time the texture sampler was busy handling texel fetch requests (that is, was either active or stalled).
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 Samplers Busy is 50, it means that texture sampler was active 50% of the rendering time for selected ergs.
- If Samplers Busy is 0, it means that texture sampler was not used or time when it was active is very small.
When the Samplers Busy is running, this might lead to execution unit stalls especially if texture fetch latency does not occur in parallel with mathematical instructions (as the shader compiler attempts to optimized shader code to cover such latencies). Examine the EU Stall % metric to see the amount of EUs stalls. If the percentage is high and Samplers Busy is close to 100%, most likely you have a texturing bottleneck. Try the 2x2 textures experiment to see if this is the case.