Profile CPU hotspots

Profile CPU hotspots in C++ — with the four heights of help laid out: do it now, make it easier for the next person to accept, work out the right move when you are stuck, and learn the pattern so it stops coming back.

4prompt heights
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The four heights

The same task, four distances: today's deadline, the next reviewer, the stuck moment, the pattern.

Execute — do the immediate task

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We need CPU hotspot data from the physics scene with 64 active ragdolls. Run a sampling profile…
We need CPU hotspot data from the physics scene with 64 active ragdolls. Run a sampling profile during the ragdoll burst, annotate hot functions, and send the call-tree and flamegraph to Jonas in physics and to me. Verify the profile covers the burst and confirm by Thursday that the top hot path accounts for at least 60% of the burst time.

Improve — make it easier to accept

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Before I send this to Jonas in physics, make the hotspot report easy to act on — show a concise…
Before I send this to Jonas in physics, make the hotspot report easy to act on — show a concise flamegraph with the top five functions expanded, quantify how much time each loop spends in lock or atomics, and flag any inlined callbacks or virtual calls that would make a reviewer hesitate to refactor.

Decide — diagnose the stuck moment

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During the ragdoll test the CPU usage doubled unexpectedly. I collected a sampling profile but I…

The physics burst doubled CPU in one test run

During the ragdoll test the CPU usage doubled unexpectedly. I collected a sampling profile but I can’t tell if the extra time is in collision detection, solver iterations, or transport overhead. I worry changing solver iteration counts will break stability. What’s the likeliest hotspot and the smallest experiment that will reveal whether solver or collision code is responsible?

Become — change the pattern

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Every sprint a merge introduces a CPU hotspot that eats frame budget and I waste hours rolling back…

Performance regressions appear after merges

Every sprint a merge introduces a CPU hotspot that eats frame budget and I waste hours rolling back changes. I keep fixing hotspots ad-hoc with micro-optimizations. Which team habit should change to prevent regressions, and what profiling gate or PR checklist would stop expensive code from landing unnoticed?

Next to this one

Other programming language work people do in C++.

Every task here came from the work, not from a feature list — which is why the prompts name what you want done and never the button that does it. The tool changes; the work does not.
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The rest of the map

Same library, five ways in.