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Without `--sample-period`, no assumptions are made about perf profile sample frequencies. This is useful for comparing relative hotness of different program locations within the same profile. With `--sample-period`, LBR- and IP-based profile hit counts are adjusted to estimate the absolute total event count for each program location. This makes it reasonable to compare hit counts between different profiles, e.g., between two LBR-based execution frequency profiles with different sampling periods or between LBR-based execution frequency profiles and IP-based branch mispredict profiles. This functionality is in support of HWPGO[^1], which aims to enable feedback from a wider range of hardware events. [^1]: https://llvm.org/devmtg/2024-04/slides/TechnicalTalks/Xiao-EnablingHW-BasedPGO.pdf