fjord: Add FastLZ L1-Cost function specs

[mdehoog]

Description

Specs for the FastLZ L1 cost function changes, targeting Fjord. See https://hackmd.io/@mdehoog/compression-analysis for a detailed write up.

Related:

• Fjord: Add FastLZ compression into L1CostFunc op-geth#249
• fjord: Fastlz GasPriceOracle optimism#10534
• Fjord: Add FastLZ compression into L1CostFunc optimism#9618

[tynes]

Are we going to want to adjust intercept, fastlzCoef, and uncompressedTxCoef dynamically? Or do you think that hardcoding these values for all networks will be sufficient? If we want to make them dynamic, then we will need a file system-config.md that describes the setters and a l1-attributes.md that describes the updates to the L1 Attributes transaction. We just optimized the L1 Attributes tx as part of ecotone to make it smaller so I am fine with adding new fields to it, I also have a diff based proposal here that could be helpful in allowing us to add many possible fields to the L1 Attributes tx without it adding bloat to the history: #13

[mdehoog]

Are we going to want to adjust intercept, fastlzCoef, and uncompressedTxCoef dynamically? Or do you think that hardcoding these values for all networks will be sufficient? If we want to make them dynamic, then we will need a file system-config.md that describes the setters and a l1-attributes.md that describes the updates to the L1 Attributes transaction. We just optimized the L1 Attributes tx as part of ecotone to make it smaller so I am fine with adding new fields to it, I also have a diff based proposal here that could be helpful in allowing us to add many possible fields to the L1 Attributes tx without it adding bloat to the history: #13

We plan to make then configurable. I've updated the relevant parts of the spec.

EDIT: we met about this and decided to derisk the upgrade by hardcoding the constants for now. We may want to introduce ability for this to be configured, either by L1 attributes or by putting the logic in an L2 contract, but for now hardcoding is fine.

[tynes]

Generally looks good

[tynes]

This looks great! Thank you. We would like to modularize the specs a bit so the diff that comes with a particular network upgrade is very obvious. If you could rebase and move the new specs into the fjord directory, that would be great. We will be going through and making directories for each network upgrade in the future

[sebastianst]

Looks great, thank you! Also confirmed that the new GPO deployment code matches the monorepo PR.