[protocol_change] Decrease function call base cost

[aborg-dev]

This PR decreases the function call base execution cost to 1TGas.
It is stacked on #10941.

[Ekleog-NEAR]

I think we need to change more gas costs than just this one in order to avoid a situation later where we’ll want to raise the per-byte cost significantly and not be able to.

To do that, I think we should:

• Reduce execution costs as decided in the meeting, because while it’s the riskiest change (with the undercharging risk) it’s also the one we expect to get most benefit from on congested shards
• Reduce send costs to like 100-500Ggas, because while we’re unsure about execution costs, send costs should definitely be much lower than that — and reducing them might help us decongest the shards by the transactions sent by other accounts on the same shard
• Increase per-byte costs, so that the maximal size of a 4MB contract stays at the same cost. This is because we likely already undercharge for large contracts, and if we don’t increase the per-byte costs at the same time as we decrease the base costs, we won’t be able to increase it later

With these changes, we’ll lower the affine function by keeping the same end and lowering the "0 size" case. The contracts we’re interested in optimizing for are on the lower end of the size spectrum, so we should reap most of the benefits, while avoiding the risk of significant undercharging for large contracts

cc @bowenwang1996 if you have an opinion on this plan?

I likely won’t have the time to do a second round of review today, so I’ll let you land based on Akhi’s approval if the discussion stabilizes, and come back tomorrow otherwise :)

[Ekleog-NEAR]

This would result in the following numbers:

• Function call base send: 2_319_861_500_000 -> 200_000_000_000
• Function call base exec: 2_319_861_500_000 -> 1_000_000_000_000
• Function call per-byte send: 2_235_934 -> 2_741_348
• Function call per-byte exec: 2_235_934 -> 2_550_613

This (rounds-down) the total cost for a 4_194_304 bytes contract (our max_contract_size) to the same value as before

[Ekleog-NEAR]

Erratum: I used the wrong costs, as pointed out by Bowen on Zulip:

The corrected estimations are:

• Function call base send: 2_319_861_500_000 -> 200_000_000_000 (estimator-provided value: ~10_000_000)
• Function call base exec: 2_319_861_500_000 -> 1_000_000_000_000 (estimator-provided value: 108_726_617_500)
• Contract loading per-byte: 216_750 -> 1_036_843 (estimator-provided value: 5_500_000)

[aborg-dev]

I've updated the costs to suggested values - this PR should be ready for testing on mocknet.

[Ekleog-NEAR]

LGTM! :) just assuming tests pass fine

[bowenwang1996]

Copy paste what I wrote on zulip: I thought the discussion here refers to a later change down the line. The issue is that if we do this change as is, then we don't gain much in terms of improving receipt throughput because when a function call receipt is executed, we charge both exec cost and wasm_contract_loading_bytes. I suggest we go with changing only exec cost now and do other changes after we have a more comprehensive understanding of the performance characteristics of runtime

[Ekleog-NEAR]

Copying here the results of the discussion from zulip: it’s probably best to go with option 3 described there, aka:

• Function call base send: 2_319_861_500_000 -> 200_000_000_000 (estimator-provided value: ~10_000_000)
• Function call base exec: 2_319_861_500_000 -> 780_000_000_000 (estimator-provided value: 108_726_617_500)
• Contract loading per-byte: 216_750 -> 1_089_295 (estimator-provided value: 5_500_000)

This gets 300kB contracts down to 1.1Tgas exec cost (the same value as just lowering function call base exec cost to 1Tgas without any other costs changes), while still keeping 4MB contracts at the same cost as before

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 71.37%. Comparing base (22427ed) to head (6b6d8eb).

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #10943      +/-   ##
==========================================
+ Coverage   66.97%   71.37%   +4.39%     
==========================================
  Files         748      760      +12     
  Lines      151539   152771    +1232     
  Branches   151539   152771    +1232     
==========================================
+ Hits       101498   109041    +7543     
+ Misses      45726    39206    -6520     
- Partials     4315     4524     +209     

Flag	Coverage Δ
backward-compatibility	0.24% <0.00%> (?)
db-migration	0.24% <0.00%> (?)
genesis-check	1.43% <0.00%> (?)
integration-tests	37.04% <0.00%> (?)
linux	69.86% <100.00%> (+3.53%)	⬆️
linux-nightly	70.85% <100.00%> (+4.36%)	⬆️
macos	54.40% <100.00%> (?)
pytests	1.65% <0.00%> (?)
sanity-checks	1.44% <0.00%> (?)
unittests	67.02% <100.00%> (+0.04%)	⬆️
upgradability	0.29% <0.00%> (?)

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