Differential flamegraphs compare raw sample counts after scaling the baseline by sampled wall time. This makes identical profiles look very different when the sampling rates differ.
For example, using a 1 kHz baseline and profiling the same workload at 100 Hz reports around -90% for unchanged leaf functions. Using the same rate for both profiles reports approximately 0%.
We should normalize the sample counts consistently and use the sampling interval only when converting samples to time for display.
Linked PRs
Differential flamegraphs compare raw sample counts after scaling the baseline by sampled wall time. This makes identical profiles look very different when the sampling rates differ.
For example, using a 1 kHz baseline and profiling the same workload at 100 Hz reports around
-90%for unchanged leaf functions. Using the same rate for both profiles reports approximately0%.We should normalize the sample counts consistently and use the sampling interval only when converting samples to time for display.
Linked PRs