CIP-0028

Abstract

This CIP extends CIP-0009 to include the new protocol parameters that have been introduced for Alonzo, specifically those relating to the costing of Plutus scripts. It describes the initial settings for those parameters.

Motivation: why is this CIP necessary?

We need to document the chain of changes to the protocol parameters. This document describes precisely the changes that have been made from CIP-0009, allowing the differences to be determined. It thus supplements rather than replaces CIP-0009.

Specification

New Updatable Protocol Parameters

The new updatable protocol parameter values for Alonzo are given below (in JSON format). Any of these parameters may be changed by submitting a parameter update proposal to the chain, and without triggering a "hard fork". Note that these parameters are given using the names used in the genesis file. Be aware that some parameters are shown differently using cardano-cli query protocol-parameters -- this has been raised as an issue with the development team.

{
    "lovelacePerUTxOWord": 34482,
    "executionPrices": {
        "prSteps":
    {
        "numerator" :   721,
        "denominator" : 10000000
        },
        "prMem":
    {
        "numerator" :   577,
        "denominator" : 10000
    }
    },
    "maxTxExUnits": {
        "exUnitsMem":   10000000,
        "exUnitsSteps": 10000000000
    },
    "maxBlockExUnits": {
        "exUnitsMem":   50000000,
        "exUnitsSteps": 40000000000
    },
    "maxValueSize": 5000,
    "collateralPercentage": 150,
    "maxCollateralInputs": 3,
    "costModels": {
        "PlutusV1": {
            "sha2_256-memory-arguments": 4,
            "equalsString-cpu-arguments-constant": 1000,
            "cekDelayCost-exBudgetMemory": 100,
            "lessThanEqualsByteString-cpu-arguments-intercept": 103599,
            "divideInteger-memory-arguments-minimum": 1,
            "appendByteString-cpu-arguments-slope": 621,
            "blake2b-cpu-arguments-slope": 29175,
            "iData-cpu-arguments": 150000,
            "encodeUtf8-cpu-arguments-slope": 1000,
            "unBData-cpu-arguments": 150000,
            "multiplyInteger-cpu-arguments-intercept": 61516,
            "cekConstCost-exBudgetMemory": 100,
            "nullList-cpu-arguments": 150000,
            "equalsString-cpu-arguments-intercept": 150000,
            "trace-cpu-arguments": 150000,
            "mkNilData-memory-arguments": 32,
            "lengthOfByteString-cpu-arguments": 150000,
            "cekBuiltinCost-exBudgetCPU": 29773,
            "bData-cpu-arguments": 150000,
            "subtractInteger-cpu-arguments-slope": 0,
            "unIData-cpu-arguments": 150000,
            "consByteString-memory-arguments-intercept": 0,
            "divideInteger-memory-arguments-slope": 1,
            "divideInteger-cpu-arguments-model-arguments-slope": 118,
            "listData-cpu-arguments": 150000,
            "headList-cpu-arguments": 150000,
            "chooseData-memory-arguments": 32,
            "equalsInteger-cpu-arguments-intercept": 136542,
            "sha3_256-cpu-arguments-slope": 82363,
            "sliceByteString-cpu-arguments-slope": 5000,
            "unMapData-cpu-arguments": 150000,
            "lessThanInteger-cpu-arguments-intercept": 179690,
            "mkCons-cpu-arguments": 150000,
            "appendString-memory-arguments-intercept": 0,
            "modInteger-cpu-arguments-model-arguments-slope": 118,
            "ifThenElse-cpu-arguments": 1,
            "mkNilPairData-cpu-arguments": 150000,
            "lessThanEqualsInteger-cpu-arguments-intercept": 145276,
            "addInteger-memory-arguments-slope": 1,
            "chooseList-memory-arguments": 32,
            "constrData-memory-arguments": 32,
            "decodeUtf8-cpu-arguments-intercept": 150000,
            "equalsData-memory-arguments": 1,
            "subtractInteger-memory-arguments-slope": 1,
            "appendByteString-memory-arguments-intercept": 0,
            "lengthOfByteString-memory-arguments": 4,
            "headList-memory-arguments": 32,
            "listData-memory-arguments": 32,
            "consByteString-cpu-arguments-intercept": 150000,
            "unIData-memory-arguments": 32,
            "remainderInteger-memory-arguments-minimum": 1,
            "bData-memory-arguments": 32,
            "lessThanByteString-cpu-arguments-slope": 248,
            "encodeUtf8-memory-arguments-intercept": 0,
            "cekStartupCost-exBudgetCPU": 100,
            "multiplyInteger-memory-arguments-intercept": 0,
            "unListData-memory-arguments": 32,
            "remainderInteger-cpu-arguments-model-arguments-slope": 118,
            "cekVarCost-exBudgetCPU": 29773,
            "remainderInteger-memory-arguments-slope": 1,
            "cekForceCost-exBudgetCPU": 29773,
            "sha2_256-cpu-arguments-slope": 29175,
            "equalsInteger-memory-arguments": 1,
            "indexByteString-memory-arguments": 1,
            "addInteger-memory-arguments-intercept": 1,
            "chooseUnit-cpu-arguments": 150000,
            "sndPair-cpu-arguments": 150000,
            "cekLamCost-exBudgetCPU": 29773,
            "fstPair-cpu-arguments": 150000,
            "quotientInteger-memory-arguments-minimum": 1,
            "decodeUtf8-cpu-arguments-slope": 1000,
            "lessThanInteger-memory-arguments": 1,
            "lessThanEqualsInteger-cpu-arguments-slope": 1366,
            "fstPair-memory-arguments": 32,
            "modInteger-memory-arguments-intercept": 0,
            "unConstrData-cpu-arguments": 150000,
            "lessThanEqualsInteger-memory-arguments": 1,
            "chooseUnit-memory-arguments": 32,
            "sndPair-memory-arguments": 32,
            "addInteger-cpu-arguments-intercept": 197209,
            "decodeUtf8-memory-arguments-slope": 8,
            "equalsData-cpu-arguments-intercept": 150000,
            "mapData-cpu-arguments": 150000,
            "mkPairData-cpu-arguments": 150000,
            "quotientInteger-cpu-arguments-constant": 148000,
            "consByteString-memory-arguments-slope": 1,
            "cekVarCost-exBudgetMemory": 100,
            "indexByteString-cpu-arguments": 150000,
            "unListData-cpu-arguments": 150000,
            "equalsInteger-cpu-arguments-slope": 1326,
            "cekStartupCost-exBudgetMemory": 100,
            "subtractInteger-cpu-arguments-intercept": 197209,
            "divideInteger-cpu-arguments-model-arguments-intercept": 425507,
            "divideInteger-memory-arguments-intercept": 0,
            "cekForceCost-exBudgetMemory": 100,
            "blake2b-cpu-arguments-intercept": 2477736,
            "remainderInteger-cpu-arguments-constant": 148000,
            "tailList-cpu-arguments": 150000,
            "encodeUtf8-cpu-arguments-intercept": 150000,
            "equalsString-cpu-arguments-slope": 1000,
            "lessThanByteString-memory-arguments": 1,
            "multiplyInteger-cpu-arguments-slope": 11218,
            "appendByteString-cpu-arguments-intercept": 396231,
            "lessThanEqualsByteString-cpu-arguments-slope": 248,
            "modInteger-memory-arguments-slope": 1,
            "addInteger-cpu-arguments-slope": 0,
            "equalsData-cpu-arguments-slope": 10000,
            "decodeUtf8-memory-arguments-intercept": 0,
            "chooseList-cpu-arguments": 150000,
            "constrData-cpu-arguments": 150000,
            "equalsByteString-memory-arguments": 1,
            "cekApplyCost-exBudgetCPU": 29773,
            "quotientInteger-memory-arguments-slope": 1,
            "verifySignature-cpu-arguments-intercept": 3345831,
            "unMapData-memory-arguments": 32,
            "mkCons-memory-arguments": 32,
            "sliceByteString-memory-arguments-slope": 1,
            "sha3_256-memory-arguments": 4,
            "ifThenElse-memory-arguments": 1,
            "mkNilPairData-memory-arguments": 32,
            "equalsByteString-cpu-arguments-slope": 247,
            "appendString-cpu-arguments-intercept": 150000,
            "quotientInteger-cpu-arguments-model-arguments-slope": 118,
            "cekApplyCost-exBudgetMemory": 100,
            "equalsString-memory-arguments": 1,
            "multiplyInteger-memory-arguments-slope": 1,
            "cekBuiltinCost-exBudgetMemory": 100,
            "remainderInteger-memory-arguments-intercept": 0,
            "sha2_256-cpu-arguments-intercept": 2477736,
            "remainderInteger-cpu-arguments-model-arguments-intercept": 425507,
            "lessThanEqualsByteString-memory-arguments": 1,
            "tailList-memory-arguments": 32,
            "mkNilData-cpu-arguments": 150000,
            "chooseData-cpu-arguments": 150000,
            "unBData-memory-arguments": 32,
            "blake2b-memory-arguments": 4,
            "iData-memory-arguments": 32,
            "nullList-memory-arguments": 32,
            "cekDelayCost-exBudgetCPU": 29773,
            "subtractInteger-memory-arguments-intercept": 1,
            "lessThanByteString-cpu-arguments-intercept": 103599,
            "consByteString-cpu-arguments-slope": 1000,
            "appendByteString-memory-arguments-slope": 1,
            "trace-memory-arguments": 32,
            "divideInteger-cpu-arguments-constant": 148000,
            "cekConstCost-exBudgetCPU": 29773,
            "encodeUtf8-memory-arguments-slope": 8,
            "quotientInteger-cpu-arguments-model-arguments-intercept": 425507,
            "mapData-memory-arguments": 32,
            "appendString-cpu-arguments-slope": 1000,
            "modInteger-cpu-arguments-constant": 148000,
            "verifySignature-cpu-arguments-slope": 1,
            "unConstrData-memory-arguments": 32,
            "quotientInteger-memory-arguments-intercept": 0,
            "equalsByteString-cpu-arguments-constant": 150000,
            "sliceByteString-memory-arguments-intercept": 0,
            "mkPairData-memory-arguments": 32,
            "equalsByteString-cpu-arguments-intercept": 112536,
            "appendString-memory-arguments-slope": 1,
            "lessThanInteger-cpu-arguments-slope": 497,
            "modInteger-cpu-arguments-model-arguments-intercept": 425507,
            "modInteger-memory-arguments-minimum": 1,
            "sha3_256-cpu-arguments-intercept": 0,
            "verifySignature-memory-arguments": 1,
            "cekLamCost-exBudgetMemory": 100,
            "sliceByteString-cpu-arguments-intercept": 150000
        }
    }
}

The meaning of the fields is:

Field	Initial Value	Description
lovelacePerUTxOWord	34482	Deposit charged per word of UTxO storage.
executionPrices	`{ "prSteps": { "numerator" : 721, "denominator" : 10000000}, "prMem": { "numerator" : 577, "denominator" : 10000 } }`	Fee per Plutus execution step and per memory unit
maxTxExUnits	`{ "exUnitsMem": 10000000, "exUnitsSteps": 10000000000 }`	Maximum number of memory units and steps in a single transaction.
maxBlockExUnits	`{ "exUnitsMem": 50000000, "exUnitsSteps": 40000000000 }`	Maximum number of memory units and steps in a single block.
maxValueSize	5000	The limit on the serialized size of the Value in each output.
collateralPercentage	150	Percentage of fee that is used as collateral for a failed transaction.
maxCollateralInputs	3	Maximum number of collateral inputs in a transaction.
costModels	`{ "PlutusV1": { ... } }`	Detailed cost models for each Plutus version.

Each version of the Plutus interpreter may use different cost model parameters and settings. Although the parameters are updatable, they are likely to be changed only when introducing new Plutus interpreter versions at a "hard fork". For simplicity, the details of the parameter settings is omitted here.

Obsoleted Updatable Protocol Parameters

minUTxOValue is no longer used. It is replaced by lovelacePerUTxOWord.

Non-Updatable Parameters

There are no changes to the non-updatable protocol parameters.

Rationale: how does this CIP achieve its goals?

The majority of the parameters are needed to enable the use of Plutus scripts on-chain. They relate to the fees calculations for transactions that include Plutus scripts.

executionPrices are specified in fractions of lovelace per Plutus CPU execution step or memory unit. These have been set to be consistent with the cost for a full transaction.

lovelacePerUTxOWord replaces minUTxOValue. Rather than determining a fixed minimum deposit, the new value scales each word that is used. The value is set to give a very similar result for an ada-only UTxO entry (previously, 1,000,000 lovelace; now 999,978 lovelace, since each ada-only UTxO entry is 29 words).

collateralPercentagehas been chosen to be higher than the transaction fee. Collateral should only be used to pay fees if a user has deliberately submitted a transaction that is known to fail. Setting the percentage high acts to discourage the submission of rogue transactions, which maliciously consume chain resources.

maxCollateralInputs has been set to allow the option of multiple inputs to be used to pay collateral, if needed (e.g. so that multiple instance of a transaction can be submitted without sharing a single collateral, that might restrict concurrency or cause script failure if the collateral was not available).

maxValueSize has been set based on benchmarking.

costModels has been set for PlutusV1 based on benchmarking inputs. Each Plutus Core primitive has associated costs.

Path to Active

Acceptance Criteria

The Alonzo ledger era is activated.
Documented parameters have been in operational use by Cardano Node and Ledger as of the Alonzo ledger era.

Implementation Plan

Alonzo ledger era parameters are deemed correct by working groups at IOG.

Copyright

This CIP is licensed under Apache-2.0.

CIP Information

This null ./CIP-0028 created on 2021-10-14 has the status: Active.
This page was generated automatically from: cardano-foundation/CIPs.

Abstract​

Motivation: why is this CIP necessary?​

Specification​

New Updatable Protocol Parameters​

Obsoleted Updatable Protocol Parameters​

Non-Updatable Parameters​

Rationale: how does this CIP achieve its goals?​

Path to Active​

Acceptance Criteria​

Implementation Plan​

Copyright​

CIP Information​