This EIP tries to set prices of certain precompiles and built-in EVM function to be in line with their performance, consumed resources and newer changes in EVM itself.
New price formulas are proposed for:
0x02)0x03)0x20)Costs of many precompiles and built-in functions are invalid at the current state of the clients. This EIP contains a list of changes to the pricing formulas to better reflect underlying computations' structure.
Historical pricing for these functions in EVM does not reflect inner structure of the underlying computations (inner structure of the hash functions).
STATICCALL (0xfa) cost to precompile and it may be necessary to adjust costs of some precompiles that may have taken old large cost (700 gas) into account and tried to compensate for itIf block_number >= X set the gas cost of the following precompiles and Keccak256 opcode:
0x02): 10 + ((len(input) + 8)/64 + 1) * 90x03): 6 + ((len(input) + 8)/64 + 1) * 120x20): 13 + (len(input)/136 + 1)*15This EIP ideally requires that MODEXP repricing is implemented to also accurately reflect that there is no implicit compensation for an old STATICCALL (0xfa) cost (pre-2046).
Cost of functions being executed must accurately reflect real CPU time spent on computations, so benchmarking was performed for current precompiles and Keccak256 function to measure running time versus input parameters.
This EIP relies on two facts:
Necessary benchmarks for EIP-2666 were provided by the clients and raw form is assembled in here
Currently it's 60 gas + 12 gas per 32 byte word (number of words is ceil(len(input)/word_len) here and in similar places. If there is no floor or ceil specifier all divisions below are integer divisions (floor divisions)). Proposed formula is A * ((len(input) + 8) / 64 + 1) + B, with coefficients below
| A | B | ||
|---|---|---|---|
| Geth | 5 | 3 | |
| OE | 9 | 4 | |
| Besu | 5 | 10 | |
| Nethermind | 10 | 5 |
EIP-2666 proposes A = 9, B = 10. There are no large one-off costs in this precompile, so it's EIP-2046 - safe.
Currently it's 600 gas + 120 gas per 32 byte word. Proposed formula is A * ((len(input) + 8) / 64 + 1) + B, with coefficients below
| A | B | ||
|---|---|---|---|
| Geth | 12 | 6 | |
| OE | 8 | 2 | |
| Besu | 29 | 16 | |
| Nethermind | 10 | 6 |
EIP-2666 proposes A = 12, B = 6. There are no large one-off costs in this precompile, so it's EIP-2046 - safe. Besu expects to have performance improvements by the end of the year.
Currently it's 30 gas + 6 gas per 32 byte word. Proposed formula is A * (len(input) / 136 + 1) + B, with coefficients below
| A | B | ||
|---|---|---|---|
| Geth | 13 | 13 | |
| OE | 15 | 2 | |
| Besu | 19 | 28 | |
| Nethermind | 16 | 3 |
EIP-2666 proposes A = 15, B = 13. There are no large one-off costs in this precompile, so it's EIP-2046 - safe. Besu expects to have performance improvements by the end of the year.
Reference material (from benchmarks of different clients) with raw data can be found here.
There is a repository available with inputs for benchmarking and precompiles testing here that can be used by client teams to perform all the necessary measurements.
Raw Besu benchmarks.
There are terms in formulas that look like A * 1 and those are explicitly not combined to the B coefficient to reflect that hash of an empty byte array requires to perform a round of hashing anyway.
Precompile repricings has happened in a past and can be considered standard procedure. Gas costs of many contracts is expected to reduce that may break re-entrancy protection measures based on fixed gas costs. In any case, such protection should have never been considered good and final.
Let's consider a simple example of Keccak256 hash of 0, 64 and 160 bytes that can is a simple sanity check for implementation.
0 bytes:
30 + 6 * ceil(0 / 32) = 30 gas15 * (0/136 + 1) + 13 = 28 gas64 bytes
30 + 6 * ceil(64 / 32) = 42 gas15 * (64/136 + 1) + 13 = 28 gas160 bytes
30 + 6 * ceil(160 / 32) = 60 gas15 * (160/136 + 1) + 13 = 43 gasThere is no reference implementation at the time of writing as it requires just a simple change of constants in major clients.
As described in backward compatibility section in some cases reduction of cost may allow e.g. re-entrancy that was not expected before, but we think that re-entrancy protection based on fixed gas costs is anyway flawed design decision.
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