Frame Analyzer: Duration of Simultaneously-Selected Draw Calls Exceeds Sum of Each Draw Call's Duration

[Cami]

Hi, community. Here's the issue:

1.  Select first draw call. (173 μs).
2.  Ctrl-Select second draw call (176 μs).
Both draw calls are now selected.
3.  The issue: Combined draw calls = 925 μs.

Video: https://screencast-o-matic.com/u/lBbd/intelgpa-frame-drawcalls

What's going on here? Is this expected, or is this an error? Any insight or help would be greatly appreciated.

[Claire_H_Intel]

Hello Cami, 

Thank you for using Intel® Graphics Performance Analyzers for your profiling and optimization needs. Graphics Frame Analyzer calculates groups such as render target regions as a single unit to allow hardware utilization to closely resemble the expected workload. Because of this it is rare for the sum of the individual timings to match the total timings. While examining a frame you should keep in mind the region times to judge the impact a change will make in the overall frame time and isolate the most expensive draw calls by analyzing individual frame timings which have the most to gain from optimization.