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Update latest L1 cost function #3

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Merged
danyalprout merged 1 commit into from
Apr 28, 2024
Merged

Update latest L1 cost function #3

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35 changes: 16 additions & 19 deletions core/types/rollup_cost.go
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Original file line number Diff line number Diff line change
Expand Up @@ -75,9 +75,10 @@ var (
fjordDivisor = big.NewInt(1_000_000_000_000)
sixteen = big.NewInt(16)

l1CostIntercept = big.NewInt(-27_321_890)
l1CostFastlzCoef = big.NewInt(1_031_462)
l1CostTxSizeCoef = big.NewInt(-88_664)
l1CostIntercept = big.NewInt(-42_585_600)
l1CostFastlzCoef = big.NewInt(836_500)

minTransactionSize = big.NewInt(71 * 1e6)

emptyScalars = make([]byte, 8)
)
Expand Down Expand Up @@ -152,7 +153,6 @@ func NewL1CostFunc(config *params.ChainConfig, statedb StateGetter) L1CostFunc {
l1BlobBaseFeeScalar,
l1CostIntercept,
l1CostFastlzCoef,
l1CostTxSizeCoef,
)
} else if config.IsOptimismEcotone(blockTime) {
l1BaseFeeScalar, l1BlobBaseFeeScalar := extractEcotoneFeeParams(l1FeeScalars)
Expand Down Expand Up @@ -336,35 +336,32 @@ func l1CostHelper(gasWithOverhead, l1BaseFee, scalar *big.Int) *big.Int {

// newL1CostFuncFjord returns an l1 cost function suitable for the Ecotone upgrade except for the
// very first block of the upgrade.
func newL1CostFuncFjord(l1BaseFee, l1BlobBaseFee, l1BaseFeeScalar, l1BlobBaseFeeScalar, l1CostIntercept, l1CostFastlzCoef, l1CostTxSizeCoef *big.Int) l1CostFunc {
func newL1CostFuncFjord(l1BaseFee, l1BlobBaseFee, l1BaseFeeScalar, l1BlobBaseFeeScalar, l1CostIntercept, l1CostFastlzCoef *big.Int) l1CostFunc {
return func(costData RollupCostData) (fee, calldataGasUsed *big.Int) {
calldataGasUsed = bedrockCalldataGasUsed(costData)
// Fjord L1 cost function:
//
// l1FeeScaled = l1BaseFeeScalar*l1BaseFee*16 + l1BlobFeeScalar*l1BlobBaseFee
// l1CostSigned = (intercept + fastlzCoef*fastlzSize + txSizeCoef*txSize) * l1FeeScaled / 1e12
// l1Cost = uint256(max(0, l1CostSigned))
//l1FeeScaled = baseFeeScalar*l1BaseFee*16 + blobFeeScalar*l1BlobBaseFee
//estimatedSize = intercept + fastlzCoef*fastlzSize
//l1Cost = max(minTransactionSize, estimatedSize) * l1FeeScaled / 1e12

calldataCostPerByte := new(big.Int).Mul(l1BaseFee, sixteen)
calldataCostPerByte.Mul(calldataCostPerByte, l1BaseFeeScalar)
blobCostPerByte := new(big.Int).Mul(l1BlobBaseFee, l1BlobBaseFeeScalar)
l1FeeScaled := new(big.Int).Add(calldataCostPerByte, blobCostPerByte)

fastlzTerm := new(big.Int).SetUint64(costData.fastlzSize)
fastlzTerm.Mul(fastlzTerm, l1CostFastlzCoef)
txSizeTerm := new(big.Int).SetUint64(costData.zeroes + costData.ones)
txSizeTerm.Mul(txSizeTerm, l1CostTxSizeCoef)
fastlzSize := new(big.Int).SetUint64(costData.fastlzSize)
fastlzSize.Mul(fastlzSize, l1CostFastlzCoef)
fastlzSize.Add(fastlzSize, l1CostIntercept)

if fastlzSize.Cmp(minTransactionSize) < 0 {
fastlzSize.Set(minTransactionSize)
}

l1CostSigned := new(big.Int).Set(l1CostIntercept)
l1CostSigned.Add(l1CostSigned, fastlzTerm)
l1CostSigned.Add(l1CostSigned, txSizeTerm)
l1CostSigned := new(big.Int).Set(fastlzSize)
l1CostSigned.Mul(l1CostSigned, l1FeeScaled)
l1CostSigned.Div(l1CostSigned, fjordDivisor)

if l1CostSigned.Sign() < 0 {
l1CostSigned.SetInt64(0)
}

return l1CostSigned, calldataGasUsed
}
}
Expand Down
4 changes: 2 additions & 2 deletions core/types/rollup_cost_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -27,7 +27,8 @@ var (
bedrockFee = big.NewInt(11326000000000)
regolithFee = big.NewInt(3710000000000)
ecotoneFee = big.NewInt(960900) // (480/16)*(2*16*1000 + 3*10) == 960900
fjordFee = big.NewInt(63852) // (-27321890 + 1031462*31 - 88664*30) * (2*16*1000 + 3*10) / 1e6 == 63852
// the emptyTx is out of bounds for the linear regression so it uses the minimum size
fjordFee = big.NewInt(2274130) // 71_000_000 * (2 * 1000 * 1e6 * 16 + 3 * 10 * 1e6) / 1e12

bedrockGas = big.NewInt(1618)
regolithGas = big.NewInt(530) // 530 = 1618 - (16*68)
Expand Down Expand Up @@ -66,7 +67,6 @@ func TestFjordL1CostFunc(t *testing.T) {
blobBaseFeeScalar,
l1CostIntercept,
l1CostFastlzCoef,
l1CostTxSizeCoef,
)

c0, g0 := costFunc(emptyTx.RollupCostData())
Expand Down