Motivation

Gas costs given by deal activation are subsidized by Cron ProveCommit message (single precommited sectors), while are paid by ProveReplicaUpdates message when snapping and by ProveCommitAggregate for batched provecommit.

This asymmetry is already underlined in Separating proof validation from sector activation.

We want here to estimate which is the difference in gas unit (and thus cost) in both scenarios.

Gas Mismatch Estimation

We operate as follows

• Consider different blocks with different ProveReplicaUpdates by different SPs
• Integrating the data with the average gas used values taken from FilFox.

What we'll have in the end will be the unit of gas needed for deal activation which will give us an estimation of what would be the overhead for deal activation in ProveCommit messages

Blocks considered

We consider two different blocks with ProveReplicaUpdates from which we'll extrapolate all the subcalls needed for deal activation and sector (re)activation which are subsidizez by cron in case of PreCommit messages.

Epoch 2843500

Epoch 2844239

Assumptions

• Cost of a unit of gas: 0.5 nanofil (5*10^{-10} FIL)
• It is an average value evaluated using the average gas fee and the average gas used of ProveCommitand ProveReplicaUpdates from FilFox on May 9th, 2023 (that is, considering Avg. Gas Fee/Avg. Gas Used in both cases)
• Average gas used for ProveCommitSector ~ 72M gas units
• Average gas used for `ProveReplicaUpdates ~272.9M gas units

Subcalls of ProveReplicaUpdates to be considered

Deal Activation

• ActivateDeals
• ClaimAllocations (verified deals only)
• BurnExported (subcall of ClaimAllocations)
• VerifyDealsforActivation
• This call can be optimised out by using the information returned from Activate Deals
• https://github.com/filecoin-project/builtin-actors/blob/7140df519fa355f966aac2d7d6f6b014b5851154/actors/miner/src/lib.rs#L4968 (Activate Deals) https://github.com/filecoin-project/builtin-actors/blob/7140df519fa355f966aac2d7d6f6b014b5851154/actors/market/src/types.rs#L106-L118
• While VerifyDealsForActivation returns only Data CIDs: https://github.com/filecoin-project/builtin-actors/blob/7140df519fa355f966aac2d7d6f6b014b5851154/actors/market/src/types.rs#L88-L97

Sector Re-activation

• ThisEpochReward
• CurrentTotalPower
• UpdatePledgeTotal
• UpdateClaimedPower

Subcalls of ProveCommitAggregate to be considered

Deal Activation

• ActivateDeals
• ClaimAllocations
• BurnExported (subcall of ClaimAllocations)
• VerifyDealsforActivation

Sector Activation

• ThisEpochReward
• CurrentTotalPower
• UpdatePledgeTotal

• UpdateClaimedPower
• UpdateClaimedPower for new sectors is called once during the first WindowPoSt after the sector is on-boarded. It will also be called only once for all new sectors in the given deadline.

ProveReplicaUpdates

• Amortized per Deal Activation gas cost ~ 100M gas unit
• Single Deal sector Deal Activation gas cost ~ 140.65M gas units
• Sector Re-Activation gas cost ~31.2M gas units

ProveCommitAggregate

• Per Deal Activation gas cost ~ 118M gas units
• Sector Activation gas cost ~ 7.1 M gas units

Estimations

We consider the case of ProveReplicaUpdates with 1 deal per sector (since it is the case we are modeling in ↗️[2023Q2] CC Sector Upgrade: Guidelines and Modeling ).

Activation Estimates

ProveCommit and ProveReplicaUpdates Gas Costs Comparison

Considering the average value for gas used by ProveReplicaUpdates ~ 273M, we have that activation gas costs (deal activation + sector activation) represent the ~ 62.9% of the gas fees.

Considering the average value for gas used by ProveCommit ~71.8M, we have that charging activation gas fees (deal activation + sector activation) to ProveCommit would increase its cost by 3x.