Base gas costs for function calls are too high

[jakmeier]

Between unpacking a function call action from a receipt and when we start executing the WASM code, there is a bunch of constant fixed overhead. The way we are charging this today is through several parameters.

The sum of all parameters seems to be approximately right but some of the individual values are completely off. Most importantly, we do not scale properly with the number of bytes in the code and instead rely on high base fees.

Reshuffling the costs to scale properly with the code size could help users with small contracts a lot. We are talking about roughly halving the base cost per function call based on today's available data.

Detailed numbers are available in this comment #7227 (comment) and the comment right below it has some more detailed explanation. Further, there is table of which parameters we can play with in this comment #6992 (comment).

A slide deck with even more details on how exactly we charge gas and which places need fixing is available here:
https://docs.google.com/presentation/d/10nqplCDpmLdzeZbVx9POwBqEYH6aSFcZOgZPA2vMK_g/edit#slide=id.g13c377cb935_0_432

[jakmeier]

Actually reshuffling at the moment is blocked by at least #5962.

Additionally, we probably also need some more optimizations and then we need reevaluate the costs.
Relevant improvements that are already somwhere in the pipleine:

• receipt prefetching (feat: prefetch accounts and access keys #7590)
• flat storage (Flat storage MVP #7327)
• wasmer side optimizations such as Enable reuse of mmaps between artifacts wasmer#125.

[nagisa]

Other related issues:

• Make the runtime operate with a bounded/constant amount of memory/time #8704
• Recompute gas costs for function call base and data creation #4401
• near-vm: Allow straightforward reuse of pre-faulted memory maps for storing executable machine code and wasm memories. #8950
• Enable reuse of mmaps between artifacts wasmer#125

[nagisa]

FWIW some work to improve how memory maps for contract loading has landed a while ago in #9244 but we done the follow up work to recalculate the costs so that these improvements make their way to the users.