FIP-0015: Revert FIP-0009 (Exempt Window PoSts from BaseFee burn)

Author	jennijuju, arajasek
Discussions-To	https://github.com/filecoin-project/FIPs/issues/86
Status	Accepted
Review period ends	2021-05-31
Type	Technical
Category	Core
Created	2021-05-20

Spec Sections

Simple Summary

Revert FIP-0009, which exempts Window PoSts from BaseFee burn.

Abstract

Do not “refund” any burned gas from any SubmitWindowedPoSt message sent on-chain.

Change Motivation

FIP-0009, which exempts select SubmitWindowedPoSt message from base-fee burn, was introduced in December, 2020, as a short-term stopgap to reduce the impact of rising base fee on the gas cost for continuously proving existing storage.

Since then, three long-term solutions for addressing this issue have been accepted in the network:

FIP-0010, which introduced optimistic acceptance of Window PoSt proofs without verification, while allowing them to be disputed later by off-chain verifiers. As a result, the GasUsed for an arbitrary SubmitWindowedPost message fell by more than 90%.
FIP-0013, which adds a ProveCommitAggregated method to condense multiple proof verifications (SNARKs) into a single aggregated message that takes up less chain bandwidth. The FIP has been accepted and will be introduced in the network in the upcoming HyperDrive upgrade. This feature will relieve the network congestion as SnarkPack can aggregate 8192 SNARK proofs, whcih allows miners to submit ProveCommitments for up to 819 sectors in one ProveCommitAggregated message.
FIP-0008, which adds a method for a miner to submit batched pre-commitments for multiple sectors. This serves to further increase chain bandwidth and will also be introduced in the network in the upcoming HyperDrive upgrade.

In addition, the “free” Window Posts distorts the gas market and reduces the incentive for miners to batch as many partitions as possible into one SubmitWindowedPoSt message, which wastes chain bandwidth.

Specification

Treat SubmitWindowedPoSt messages the same as all others for the purpose of gas accounting. Specifically, do NOT “refund” any burned gas when accounts send successful message to a miner actor’s SubmitWindowedPoSt method.

Design Rationale

The simple design is to simply stop applying the rule introduced in FIP-0009 past a certain point.

Backwards Compatibility

This FIP requires a network upgrade at a specific epoch to ensure that all node operators abide by the new pricing rules after that epoch.

Test Cases

After the change, the “GasCost” of a successful, direct SubmitWindowedPoSt message must change from:

{
  "Message": {
    "/": "bafy2bzacedhftxcnozkaeleau4szu2vpvksbjs2xkpracp6xvdog6gucnzxdc"
  },
  "GasUsed": "125122238",
  "BaseFeeBurn": "0",
  "OverEstimationBurn": "466093200",
  "MinerPenalty": "0",
  "MinerTip": "15543374565710",
  "Refund": "151788019038",
  "TotalCost": "15556352882710"
}

To:

{
  "Message": {
    "/": "bafy2bzacedfyp5mz6le43iifaviw2g7hgiqr3eet2bfdzffbitphyubjzzgpy"
  },
  "GasUsed": "125122238",
  "BaseFeeBurn": "12512223800",
  "OverEstimationBurn": "466093200",
  "MinerPenalty": "0",
  "MinerTip": "15723304407057",
  "Refund": "164300242838",
  "TotalCost": "15723770500257"
}

Specifically, the BaseFeeBurn is NOT 0.

Security Considerations

This FIP is strictly an increase in security, since it does away with the minor risks introduced in FIP-0009 (see here).

Incentive Considerations

The FIP leads to more FIL being burned through the act of proving storage, making it marginally more expensive for miners to be a part of the network. However, this cost is insignificant, less than 1/60th the FIL burned through onboarding storage. The overall cost is about 10,000 FIL per week.

The FIP disincentivizes miners from splitting their partitions across multiple SubmitWindowedPost messages, which is an overall improvement to chain capacity. Risk-averse miners can continue to do so, paying a fair price.

The FIP has no impact on the incentive for miners to select SubmitWindowedPost messages to be included in their blocks.

Product Considerations

After the network upgrade, miners should pay attention to the fee cap of SubmitWindowedPost message to avoid unexpected and unnecessary base fee burn.

Implementation

PENDING PR

Copyright

Citation

Please cite this document as:

jennijuju, arajasek, "FIP-0015: Revert FIP-0009 (Exempt Window PoSts from BaseFee burn)," Filecoin Improvement Proposals, no. 0015, May 2021. [Online serial]. Available: https://fips.fission.app/fips/fip-0015.

FIP-0015: Revert FIP-0009 (Exempt Window PoSts from BaseFee burn) Source