[RF] RooFFTConvPdf: cache norm. val to avoid bookkeeping during scan#21615
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guitargeek merged 1 commit intoroot-project:masterfrom Mar 16, 2026
Merged
[RF] RooFFTConvPdf: cache norm. val to avoid bookkeeping during scan#21615guitargeek merged 1 commit intoroot-project:masterfrom
guitargeek merged 1 commit intoroot-project:masterfrom
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`RooFFTConvPdf::scanPdf()` repeatedly evaluates the component pdfs with `pdf.getVal(normSet)` while filling the FFT input buffers. For large scans this incurs unnecessary overhead from `RooAbsPdf::getValV()`'s normalization-set tracking and cache management, even though the normalization set is fixed for a given FFTCacheElem. This change caches the normalization integrals for both component pdf clones (normVal1, normVal2) when the FFTCacheElem is constructed. During scanning, the pdfs are then evaluated without passing a normalization set and are normalized manually using the cached integral values. To exactly reproduce `RooAbsPdf::getValV()` behaviour (including NaN-packing semantics), the `RooAbsPdf::normalizeWithNaNPacking(rawVal, normVal)` helper function was moved to an internal helper namespace. This reduces evaluation overhead in FFT convolutions while preserving bitwise-equivalent normalization behaviour.
Test Results 22 files 22 suites 3d 4h 45m 56s ⏱️ Results for commit af10789. |
lmoneta
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Mar 16, 2026
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LGTM!
Thanks Jonas for this improvement!
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RooFFTConvPdf::scanPdf()repeatedly evaluates the component pdfs withpdf.getVal(normSet)while filling the FFT input buffers. For large scans this incurs unnecessary overhead fromRooAbsPdf::getValV()'s normalization-set tracking and cache management, even though the normalization set is fixed for a given FFTCacheElem.This change caches the normalization integrals for both component pdf clones (normVal1, normVal2) when the FFTCacheElem is constructed. During scanning, the pdfs are then evaluated without passing a normalization set and are normalized manually using the cached integral values.
To exactly reproduce
RooAbsPdf::getValV()behaviour (including NaN-packing semantics), theRooAbsPdf::normalizeWithNaNPacking(rawVal, normVal)helper function was moved to an internal helper namespace.This reduces evaluation overhead in FFT convolutions while preserving bitwise-equivalent normalization behaviour.
Spinoff from #21343 to reduce the size of the "internal" computation graphs a bit that are not visible to the
RooFit::Evaluator.