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Merge pull request #18252 from linasm/optimize-float-histogram-kahan-add

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perf(PromQL): improve performance of FloatHistogram.KahanAdd
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George Krajcsovits 2026-03-06 19:06:25 +01:00 committed by GitHub
commit f659ca383a
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GPG Key ID: B5690EEEBB952194
1 changed files with 24 additions and 16 deletions
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40
model/histogram/float_histogram.go
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@ -465,16 +465,14 @@ func (h *FloatHistogram) KahanAdd(other, c *FloatHistogram) (updatedC *FloatHist
return c, counterResetCollision, nhcbBoundsReconciled, nil
}
otherC := other.newCompensationHistogram()
var (
hNegativeSpans = h.NegativeSpans
hNegativeBuckets = h.NegativeBuckets
otherNegativeSpans = other.NegativeSpans
otherNegativeBuckets = other.NegativeBuckets
cNegativeBuckets = c.NegativeBuckets
otherCPositiveBuckets = otherC.PositiveBuckets
otherCNegativeBuckets = otherC.NegativeBuckets
otherCPositiveBuckets []float64
otherCNegativeBuckets []float64
)
switch {
@ -492,16 +490,22 @@ func (h *FloatHistogram) KahanAdd(other, c *FloatHistogram) (updatedC *FloatHist
h.Schema = other.Schema
case other.Schema > h.Schema:
otherPositiveSpans, otherPositiveBuckets, otherCPositiveBuckets = kahanReduceResolution(
otherPositiveSpans, otherPositiveBuckets, otherCPositiveBuckets,
other.Schema, h.Schema,
false,
)
otherNegativeSpans, otherNegativeBuckets, otherCNegativeBuckets = kahanReduceResolution(
otherNegativeSpans, otherNegativeBuckets, otherCNegativeBuckets,
other.Schema, h.Schema,
false,
)
if len(otherPositiveBuckets) > 0 {
otherCPositiveBuckets = make([]float64, len(otherPositiveBuckets))
otherPositiveSpans, otherPositiveBuckets, otherCPositiveBuckets = kahanReduceResolution(
otherPositiveSpans, otherPositiveBuckets, otherCPositiveBuckets,
other.Schema, h.Schema,
false,
)
}
if len(otherNegativeBuckets) > 0 {
otherCNegativeBuckets = make([]float64, len(otherNegativeBuckets))
otherNegativeSpans, otherNegativeBuckets, otherCNegativeBuckets = kahanReduceResolution(
otherNegativeSpans, otherNegativeBuckets, otherCNegativeBuckets,
other.Schema, h.Schema,
false,
)
}
}
h.PositiveSpans, h.PositiveBuckets, c.PositiveBuckets = kahanAddBuckets(
@ -1600,7 +1604,9 @@ func kahanAddBuckets(
} else if spansA[0].Offset == indexB {
// Just add to first bucket.
bucketsA[0], compensationBucketsA[0] = kahansum.Inc(bucketB, bucketsA[0], compensationBucketsA[0])
bucketsA[0], compensationBucketsA[0] = kahansum.Inc(compensationBucketB, bucketsA[0], compensationBucketsA[0])
if compensationBucketB != 0 {
bucketsA[0], compensationBucketsA[0] = kahansum.Inc(compensationBucketB, bucketsA[0], compensationBucketsA[0])
}
goto nextLoop
}
iSpan, iBucket, iInSpan = 0, 0, 0
@ -1614,7 +1620,9 @@ func kahanAddBuckets(
iBucket += int(deltaIndex)
iInSpan += deltaIndex
bucketsA[iBucket], compensationBucketsA[iBucket] = kahansum.Inc(bucketB, bucketsA[iBucket], compensationBucketsA[iBucket])
bucketsA[iBucket], compensationBucketsA[iBucket] = kahansum.Inc(compensationBucketB, bucketsA[iBucket], compensationBucketsA[iBucket])
if compensationBucketB != 0 {
bucketsA[iBucket], compensationBucketsA[iBucket] = kahansum.Inc(compensationBucketB, bucketsA[iBucket], compensationBucketsA[iBucket])
}
break
}
deltaIndex -= remainingInSpan