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title: Align incentives for access list provisioning | ||
description: This EIP proposes updating gas cost parameters for access lists to incentivize their use, aiming to improve efficiency in transaction execution. | ||
author: Ben Adams (@benaadams), Oleg Iakushkin (@OlegJakushkin) | ||
discussions-to: <URL> | ||
status: Draft | ||
type: Standards Track | ||
category: Core | ||
created: 2024-05-12 | ||
requires: EIP-2930 | ||
--- | ||
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## Abstract | ||
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To facilitate future developments of parallel data load, we need to | ||
encourage as many transactions as possible that contain as complete and | ||
valid access lists. Current access list pricing does not sufficiently incentivize their inclusion, and this EIP aims to address this gap. | ||
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## Motivation | ||
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While [eip-2930](https://eips.ethereum.org/EIPS/eip-2930) introduced `accessLists` as a mechanism for `SLOAD` | ||
pre-warming to reduce gas costs by informing the EVM upfront about which storage slots a transaction will access, | ||
the practical use is limited and uncommon due to the savings versus penalties involved. In order to break even for | ||
each address included `24 storage keys` are required per address, and there is a `100 gas` saving per key at `25+`; | ||
in contrast the penalty for including an unused key is `1900 gas`, so break-even where one key is unused is `43 keys`.\ | ||
\ | ||
This situation makes the break-even and risk-reward ratio of `accessLists` rarely appealing in practice for regular | ||
transactions, where a prior transaction could lead to a different branch being taken and a slightly different set of | ||
storage slots being accessed. Furthermore, a very high number of SLOADs is required to start breaking even.\ | ||
\ | ||
For some clients, data loading takes `>70%` of block execution time. This | ||
happens in part due to sequential transaction execution and iterative | ||
search of effectively random access data.\ | ||
\ | ||
While NVMe drives have massive throughput and IOPS; this is their | ||
concurrent throughput operated through multiple queues and they do not | ||
have this performance if data is accessed completely sequentially with | ||
one request waiting for the prior to complete i.e. stacking individual | ||
IOPS latency end to end will not give anything close to maximal | ||
throughput that these drives can deliver (which is different from the | ||
HDD world where heads needed to seek to different physical locations for | ||
each read). This is a similar situation with network attached storage or | ||
cloud data disks; however the latency here is even more amplified than a | ||
local direct CPU attached NVMe drive (i.e. via network card).\ | ||
\ | ||
If nodes had a somewhat clearer picture of what data to pre-load for the | ||
block's execution; that can be done in parallel, hiding much of the | ||
latency from accessing that data when discovered from executing the | ||
transaction. Very much in a similar way to instruction pipelining on a | ||
CPU hiding memory access latencies; the data access for transactions | ||
could be pipelined. This can lead to faster/cheaper block execution and | ||
would facilitate data dependency hints for parallel Tx execution in the | ||
future, like on other emerging chains that were developed with more | ||
modern hardware in mind. | ||
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## Specification | ||
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We shall update [eip-2930](https://eips.ethereum.org/EIPS/eip-2930) | ||
parameters: | ||
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| Constant | Value | | ||
| - | - | | ||
| `ACCESS_LIST_STORAGE_KEY_COST` | 320 | | ||
| `ACCESS_LIST_ADDRESS_COST` | 512 | | ||
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## Rationale | ||
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As stated in the introduction the gas cost benefit analysis does not | ||
encourage the users of the chain to provide accessList hints, even | ||
though the mechanism is already in protocol (and a call to | ||
`eth_createAccessList` will give them, or a wallet the correct list | ||
to include). So we propose a reduction in the pricing of those data | ||
access lists to make them more inline with calldata.\ | ||
\ | ||
Levelling the playing field between small `call_data` and `access_lists` | ||
costs, (and incentivise `access_lists` provisioning from transaction | ||
senders as they are needed for transaction execution in a faster | ||
manner), the price model updates would look as follows: | ||
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Use `STANDARD_TOKEN_COST * tokens_in_access_lists`, where | ||
`tokens_in_access_lists = bytes_in_access_lists * 4`, making it as | ||
expensive to send as plain small call data. So we will get: | ||
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- `32*4*4 = 512` for addresses (instead of 2400, 4.6 times less) | ||
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- `20*4*4 = 320` for storage keys (instead of 1900, 5.9 times less) | ||
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This means users pay for on-chain data inclusion as usual `call_data`. It | ||
changes the original | ||
[eip-2930](https://eips.ethereum.org/EIPS/eip-2930) logic | ||
of "covering the bandwidth costs", which was not described in detail and | ||
is potentially outdated. | ||
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It should be noted that this is not the first time [eip-2930](https://eips.ethereum.org/EIPS/eip-2930) additions have been proposed. In [eip-3521](https://eips.ethereum.org/EIPS/eip-3521), a reduction was already proposed, but it focused only on `ACCESS_LIST_ADDRESS_COST`. | ||
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### Examples | ||
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Current | ||
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| Inst | Type | Access List | Keys for address | OP Price | AccessList Key Price | AccessList Address Price | Total gas per OP | | ||
|------|------|-------------|------------------|----------|----------------------|-------------------------|------------------| | ||
| `SLOAD` | Cold | Not included | - | 2100 | 0 | 0 | 2100 | | ||
| `SLOAD` | Warm | Not included | - | 100 | 0 | 0 | 100 | | ||
| `SLOAD` | Warm | Included | - | 100 | - | - | 100 | | ||
| `SLOAD` | Cold | Included | 1 | 100 | 1900 | 2400 | 4400 | | ||
| `SLOAD` | None | Included | 1 | 0 | 1900 | 2400 | 4300 | | ||
| `SLOAD` | Cold | Included | 10 | 100 | 1900 | 240 | 2240 | | ||
| `SLOAD` | None | Included | 10 | 0 | 1900 | 240 | 2140 | | ||
| `SLOAD` | Cold | Included | 50 | 100 | 1900 | 48 | 2048 | | ||
| `SLOAD` | None | Included | 50 | 0 | 1900 | 48 | 1948 | | ||
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Proposed | ||
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| Inst | Type | Access List | Keys for address | OP Price | AccessList Key Price | AccessList Address Price | Total gas per OP | | ||
|-------|------|---------------|------------------|----------|----------------------|-------------------------|------------------| | ||
| `SLOAD` | Cold | Not included | - | 2100 | 0 | 0 | 2100 | | ||
| `SLOAD` | Warm | Not included | - | 100 | 0 | 0 | 100 | | ||
| `SLOAD` | Warm | Included | - | 100 | - | - | 100 | | ||
| `SLOAD` | Cold | Included | 1 | 100 | 320 | 512 | 932 | | ||
| `SLOAD` | None | Included | 1 | 0 | 320 | 512 | 832 | | ||
| `SLOAD` | Cold | Included | 10 | 100 | 320 | 51.2 | 471 | | ||
| `SLOAD` | None | Included | 10 | 0 | 320 | 51.2 | 371 | | ||
| `SLOAD` | Cold | Included | 50 | 100 | 320 | 10.24 | 430 | | ||
| `SLOAD` | None | Included | 50 | 0 | 320 | 10.24 | 330 | | ||
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\- Already paid on making warm | ||
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## Backwards Compatibility | ||
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This EIP makes a minor update to | ||
[eip-2930](https://eips.ethereum.org/EIPS/eip-2930) with | ||
respect to modern execution challenges and capabilities. | ||
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## Security Considerations | ||
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Same as per | ||
[eip-2930](https://eips.ethereum.org/EIPS/eip-2930) | ||
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## Copyright | ||
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Copyright and related rights waived via [CC0](../LICENSE.md). |