flame graph

A flame graph is a graphical representation used to visualize function costs and relationships in code execution. It is particularly useful for performance analysis and optimization. The width of the bars in a flame graph represents the time a function took to execute, while the rows represent nested call stacks. Different colors are used to indicate the source of the code, such as system frameworks, the Swift runtime, or custom app binaries.

Flame graphs can be generated using tools like Instruments in Xcode, which provide a high-level overview of trace execution. They help identify performance bottlenecks by showing which parts of the code are consuming the most CPU time. For example, in the session "Optimize CPU performance with Instruments," a flame graph is used to show execution visually, highlighting the overhead of emitting signposts and the exact calls made over time on the CPU.

For more details, you can refer to the session Optimize CPU performance with Instruments (16:36) where flame graphs are discussed in the context of CPU performance optimization.