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3.4.4. Analyzing graphs

The Performance Analysis Tool enables you to view counters as graphs. You can determine problem areas by comparing graphs against each another.

  1. In the Performance Analysis Tool, display the following counters as graphs:

    • Geometry Processor Frame Rate

    • Pixel Processor Frame Rate

  2. Compare the overall GPU Frame Rate to the graphs. You can make a number of comparisons to locate performance bottlenecks:

    1. Look for a processor that has a frame rate number similar to the overall GPU Frame Rate. This means that processor might be the limiting factor. Consider optimizing for this processor first.

    2. If no processor has a similar frame rate, look for the lowest frame rate. This indicates the processor with the lowest performance. Optimize for this processor, optimizing for other processors has no impact on performance.

    3. If there is no under-performing processor look for the graph with the most similar shape to the overall frame rate graph. This is likely to be the dominant performance factor.

    4. If the overall GPU frame rate and other frame rate counters show no correlation, investigate the CPU.

    5. If it is difficult to find a correlation, investigate memory bandwidth. Bandwidth limitations can impact all results in unpredictable ways.

Graphs can be volatile. The relative performance of the different processors can change from one frame to another:

  • look for the average rate over time to find where to make general performance improvements

  • look at performance on a frame by frame basis to find areas in specific scenes to optimize.

Note

  • A graph can indicate the general problem area. You might want to take more measurements to isolate the exact problem. See Finding exact problem areas.

  • Also ensure that you have VSYNC off when taking measurements because this can create incorrect measurements.

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